sustainability

Article Influence of the Adaptation of to on the Climate inside an Apartment under Cloudy Sky

Erika Dolníková 1 , Dušan Katunský 1,* , Zuzana Mi ˇnová 1 and Bystrík Dolník 2

1 Department of and Building Structures, Faculty of Civil Engineering, Technical University of Kosice, 04001 Kosice, ; [email protected] (E.D.); [email protected] (Z.M.) 2 Department of Electric Power Engineering, Faculty of Electrical Engineering and Informatics, Technical University of Kosice, 04001 Kosice, Slovakia; [email protected] * Correspondence: [email protected]; Tel.: +421-055-602-4157

Abstract: The reconstruction of balconies and loggias is a key element of the renovation of apartment . Artificial light will never replace natural light. Every day, one must make full use of the potential of daylight and enjoy an advantage—free-of-charge natural light entering the interior. When renovating balconies, people often change the character of this protruding structure from a façade to a . This is also the subject of this paper. For the evaluation of the daylighting conditions prevailing in residential building, the Daylight Factor (DF) was considered as the parameter for indicating the quantity of admitted daylight. The DF values and illuminance—CIE overcast sky were calculated using DIALux 9.1 software. The aim of the paper is to compare two variants of the level   of daylight in the of the residential building. One option to bring in even more natural light than a is a variant with balconies. Loggias are satisfactory in terms of static and thermal Citation: Dolníková, E.; Katunský, D.; technology, but daylight conditions are deteriorating. The article provides an insight into the solution Miˇnová,Z.; Dolník, B. Influence of the of the renovation of balconies and loggias in a specific apartment building. The result shows their Adaptation of Balconies to Loggias on influence on changes in the conditions of natural daylight in the interior of two selected rooms. the Lighting Climate inside an Apartment Building under Cloudy Keywords: ; loggia; daylighting; simulation; environment; residential building Sky. Sustainability 2021, 13, 3106. https://doi.org/10.3390/su13063106

Academic Editors: Lambros T. Doulos and Aris Tsangrassoulis 1. Introduction People are spending more and more time indoors and losing outdoor direct contact Received: 7 February 2021 with the sun’s rays. The importance of daylight consists of three basic dimensions’ the Accepted: 9 March 2021 field of health, the field of performance, and the feeling of well-being [1,2]. The “Indoor Published: 12 March 2021 Generation” is taking the health risk of spending more time inside. People do not fully comprehend the sheer amount of time they are spending inside. This detachment from the Publisher’s Note: MDPI stays neutral natural world—and natural sunlight, specifically—can have negative health impacts and with regard to jurisdictional claims in can even have deleterious effects as serious as respiratory problems or seasonal affective published maps and institutional affil- disorder. Daylight has a large influence on environmental conditions to improve ambience, iations. visual comfort, well-being, and the health of occupants [3–7]. Neuroscientist and lecturer of medicine at Harvard Medical School, Steven Lockley explains that light, as an “acute stimulant that directly alerts the brain,” can affect sleep, alertness, and human productivity. If you are exposed to brighter and bluer light in the Copyright: © 2021 by the authors. daytime, then you get a better stimulant effect. You will be more alert and have better Licensee MDPI, Basel, Switzerland. cognitive function. A potential solution to the disruptiveness of indoor living is a form of This article is an open access article architectural design—the Circadian [3–7]. distributed under the terms and Approaches to daylight design are diverse, depending on many facts, but their goal conditions of the Creative Commons is the same—to provide optimal solutions for daylighting in building interiors [8]. The Attribution (CC BY) license (https:// influence of lighting on the mental and physical state of a person is now generally known creativecommons.org/licenses/by/ and recognized. When designing interior spaces, it is therefore necessary to create adequate 4.0/).

Sustainability 2021, 13, 3106. https://doi.org/10.3390/su13063106 https://www.mdpi.com/journal/sustainability Sustainability 2021, 13, 3106 2 of 24

lighting conditions for their users resulting from the parameters of visual tasks, i.e., the so-called visual well-being [9,10]. However, visual comfort is not only dependent on the intensity of light but also, for ex- ample, on its quality or the color scheme of the interior [11,12]. Balconies produce impacts in four factors that contribute to the indoor environmental quality (thermal, visual, acoustic comfort, and indoor air quality) [13–15]. The light reflectance value is an important param- eter when the main part of the daylight contribution comes from the internally reflected component as in the case of a deep and long balcony [16,17]. The authors of [18] developed a framework called the residential daylight score. This also notes that research on daylighting focuses on office spaces, with limited study on residential spaces [18]. The authors of [19–21] found that there is limited significant proof for the link between daylight and health. According to the authors of [22] the important attributes for design in residential buildings are quality of view and brightness of surfaces. The authors of [20] reported that external obstruction is an important physical parameter affecting luminous comfort. Furthermore, this study noted that for a moderate circadian rhythm external obstruction should have a value of 0.3 for 75% of the year. This study also reported that a WWR (window– ratio) of 60% is required in a with a depth of 4–6 m [23,24]. Morning light exposure (period 6 a.m.–10 a.m.) is important for circadian rhythm. It is a biological rhythm with a period of 20–28 h ( circa = “around”, “during”, dies = “day”). Circadian rhythm is one of the biorhythms, i.e., fluctuations in activity and vigilance, most often with a daily, monthly, or annual period. Chronobiology deals with rhythms of various lengths. It is important for organisms that the circadian rhythm be aligned with the rhythm of day and night. In humans, a decrease in daylight causes an increase in the level of the hormone melatonin, which facilitates sleep. The course of the circadian rhythm itself has an effect on the performances of individual people [25]. Flats in prefabricated have become more and more popular in recent years; their prices are rising, and housing standards are rising along with them. Residents of housing estates expect from the modernization not only savings on heating but also enlargement of the balcony or loggia and beautification of the external appearance [26,27]. Balconies have become decorative features, repeated at regular intervals across a façade, they create a strong sense of coherence and unity in the design. Over years they not only got larger but they have also taken a variety of forms. Some with at least one solid side wall for privacy or with screens or there are full-height railings—often on the side in shade or on the side away from the better view out—and these screens are often combined with built-in troughs for plants [28]. In apartment buildings in the late 19th and early 20th century, only some apartments were given balconies. Perhaps those on the corner or in the center—so the balconies were really just decorative, to “articulate” or add interest to the façade. Most are too shallow to be used for anything more than a few plants and are certainly not intended to be used by the tenants for sitting outside [28]. However, by the 1930s it became common for every apartment or at least the majority of apartments in a block to have a balcony and, in some buildings, this proliferation of small balconies dominates the design of the facade to the point where the balconies, when seen from the street, take on the character of a pattern or texture across the whole front. Balconies in the 1930s and later were seen as important private outdoor space and very important for bringing fresh air and as much light as possible into an apartment [28]. Horizontal structures protruding from the vertical perimeter wall into free space, e.g., balconies or loggias form an important architectural element of buildings. In addition to fulfilling an aesthetic function, they are also used for resting or for growing ornamental or useful plants. The reconstruction of balconies and loggias is a key element of the renovation of apartment buildings. Damage is often extensive and also affects the static safety and functional properties of the buildings. Figure1 illustrates how the different parameters affect the daylight of a side-lighted workspace [29]. Sustainability 2021, 13, x FOR PEER REVIEW 3 of 25

Sustainability 2021, 13, 3106 3 of 24 safety and functional properties of the buildings. Figure 1 illustrates how the different parameters affect the daylight of a side-lighted workspace [29].

Daylight availability Room design - latitude - location - longtitude - proportions - facade oriantations - optical properties Daylight of side lighted spaces Window design Obstructions - area - location - geometry - proportions - location - optical properties - optical properties

Figure 1. Parameters influencinginfluencing the daylight of side-lightedside-lighted spacesspaces (according(according toto [[29])29]).. Balconies and loggias have become a very common feature of prefabricated flats, and Balconies and loggias have become a very common feature of prefabricated flats, and the inhabitants use them mainly for recreation and leisure. In terms of function, the loggia the inhabitants use them mainly for recreation and leisure. In terms of function, the loggia is comparable to a balcony. The differences are mainly in the degree of protection against is comparable to a balcony. The differences are mainly in the degree of protection against atmospheric influences, which is higher for loggias. This fact is important not only from atmospheric influences, which is higher for loggias. This fact is important not only from the point of view of construction protection but also from the point of view of user comfort. the point of view of construction protection but also from the point of view of user The disadvantages of the loggia compared to the balcony are worse view and less visual comfort. The disadvantages of the loggia compared to the balcony are worse view and connection with the surrounding environment [30]. less visual connection with the surrounding environment [30]. The balcony is a horizontal planar structure protruding from the perimeter wall in The balcony is a horizontal planar structure protruding from the perimeter wall in front of the building. It is accessible from inside of the building. At least part of the decisive front of the building. It is accessible from inside of the building. At least part of the supporting structure (cantilever plate, supporting cantilever beams) statically acts as a decisive supporting structure (cantilever plate, supporting cantilever beams) statically bracket, or the whole structure is suspended in front of the perimeter wall. The construction ofacts the as balcony a bracket, is usually or the whole open-type structure on three is suspended sides. The loggiain front is of a structure the perimeter accessible wall. from The insideconstruction of the building.of the balcony The horizontal is usually supportopen-type plate on staticallythree sides. acts The as aloggia simple is plate a structure and is supportedaccessible from by vertical inside ,of the , building. or The through horizontal frames. support It is usually plate statically bounded acts on three as a sidessimple by plate walls and [31 is]. supported by vertical walls, columns, or through frames. It is usually boundedHowever, on three when sides designing by walls balconies [31]. and loggias, it is good to be aware of, for example, theirHowever, influence on when daylight. designing By designing balconies a horizontaland loggias, shading it is good barrier to such be aware as a balcony of, for panelexample, above their the influence window opening,on daylight. the interiorBy designing will be a shaded, horizontal and shading thus the barrier level of such daylight as a inbalcony the room panel will above be reduced the window and the opening, quality the of theinterior indoor will environment be shaded, and will th beus degraded. the level Theof daylight brightness in the of theroom sky will at thebe reduced zenith is and always the higherquality thanof the the indoor brightness environment on the horizon. will be Indegraded. the case The of winter brightness cloudy of the skies sky with at the dark zenith terrain, is always this difference higher than is the threefold brightness [32]. on It followsthe horizon. from In these the case facts of thatwinter placing cloudy the skies balcony with dark structure terrain, above this thedifference window is threefold opening means[32]. It that follows the brightestfrom these part facts of thatthe sky placing will be theshaded balcony and structure thus the above largest the source window of daylightopening means will be that shaded. the brightest From the part current of the knowledge,sky will be shaded it can beand said thus that the thelargest difference source betweenof daylight dark- will and be shaded. light-painted From loggia the current can be knowledge, up to about it 30% can of be the said value that of the the difference daylight factor.between However, dark- and this light value-painted does loggia not apply can inbe generalup to about and 30% always of the depends value of on the the daylight overall geometryfactor. However, of the room this value and the does external not apply shading in general obstacles and [ 33always]. The depends information on the provided overall hasgeometry been obtained of the room from and several the ex contributionsternal shading in theobstacles recent [33]. past. The information provided has beenThe effectobtained of the from reflection several ofcontributions the façade onin the outdoorrecent past. microclimate can be seen in referenceThe effect [34], where of the anreflection Italian caseof the study façade is presented on the outdoor in the journalmicroclimateSustainable can be Cities seen and in Societyreference. Private [34], where outdoor an spaces—balconies Italian case study andis presented loggias in in Latvia—are the journal the Sustainable subject dealt Cities with and bySociety book. Private author outdoorJ. Prikulis spaces [35].— Thebalconies issues concerning and loggias the in design Latvia— ofare loggia the elements subject dealt are addressedwith by book in reference author J. [Prikulis36] and those[35]. The concerning issues concerning balconies in the reference design [of37 loggia]. On balconies, elements itare is possible addressed to use in reference parapet masonry [36] and for those the application concerning of photoelectricbalconies in cells reference [38]. Balconies[37]. On affectbalconies thermal, it is comfortpossible [to39 ],use their parapet glazing masonry not only for affects the application the perception of photoelectric of daylight cells but also[38]. affectsBalconies the affect thermal-humidity thermal comfort climate [39], intheir flats glazing in prefabricated not only affects buildings the perception [40]. These of glazed balconies act as passive greenhouse systems. Their potential use is reported in , for example, reference [41]. An overall study of the impact of balconies on the quality of the environment in flats as well as the overall renovation of the building, taking Sustainability 2021, 13, x FOR PEER REVIEW 4 of 25

daylight but also affects the thermal-humidity climate in flats in prefabricated buildings Sustainability 2021, 13, 3106 [40]. These glazed balconies act as passive greenhouse systems. Their potential use4 of 24 is reported in Poland, for example, reference [41]. An overall study of the impact of balconies on the quality of the environment in flats as well as the overall renovation of the building, takinginto account into account the sustainability the sustainability of construction of construction in the BIM in environment, the BIM environment, was presented was presentedlast year inlast the year journal in the Sustainabilityjournal Sustainability[42]. In [42]. addition In addition to balconies, to balconies as, we as we present present in inthis this article, article, another another option option is is the the loggia loggia through through which which it it is is possible possible toto getget accessaccess toto the exterior. Balconies, loggias loggias,, and various thin thin-walled-walled units in large large,, prefabricated prefabricated buildings are described in reference [[43].43]. ModificationsModifications (fo (forr example) of loggia extensions impact daylight and and sunlight sunlight [44 [44]] as well as well as possible as possible thermal thermal bridges [ bridges45] or the [45] overall or airtightnessthe overall airtightnessof buildings of [46 buildings]. Modifications [46]. Modifications of these structural of these elements, structural i.e., elements, balconies i.e. and, balconies loggias, andaffect loggias the impact, affect of naturalthe impact lighting, of natural energy lighting, savings, energyand visual savings comfort., and These visual aspects comfort. are Thesebeing exploredaspects are in being collaboration explored in in collective collaboration housing in collective [47]. The housing latter is a[47]. case The study latter in is the a casecontext study of existingin the context Algerian of existing buildings. Algerian buildings. Some literary literary sources sources use use dynamic dynamic metrics metrics ( (daylightdaylight auton autonomy,omy, useful useful daylight daylight,, etc.). etc.). They are are based based on on local local series series of of climate climate data data because because they they are able are ableto capture to capture the pecu- the peculiaritiesliarities of the of local the local climate, climate, including including daylight daylight and seasonal and seasonal changes changes in daylight. in daylight. Such Suchexamples examples can be can found be found in the in evaluation the evaluation of lighting of lighti conditionsng conditions in in [Italy48,49 [48]. ,49]. The method presented a practical procedure, which can be easily implemented in computer software, software, to to derive derive lighting lighting on on the the surfaces surfaces of of urban urban canyons canyons with with balconies balconies in sunnyin sunny areas, areas, allowing allowing the the designer designer to to explore explore a a number number of of options options found found in in [50].[50]. The devdevelopmentelopment of of this this method method is is based based on on the the division division of of an an urban urban canyon canyon into into a series a series of interconnectedof interconnected structural structural elements elements for for the the purpose purpose of of lighting lighting calculations calculations using using flowflow transmissiontransmission equations. InIn Slovakia, almost almost 70% 70% of the total number of apartment bui buildingsldings are built with panel technology. It It can can be said that that,, in such panel technologies, most apartments are equipped with with balconies. balconies. Their Their service service life life is isnot not high, high, so so in inthe the last last period period as aswell well as asin thein the present, present, a anumber number of of prefabricated prefabricated houses houses are are bein beingg reconstructed. During the reconstruction,reconstruction, the balconies are sometimes changedchanged toto loggias. This fact is also the subject of this paper. There are several repetitive flats flats on floors and sections in the housing estate Kosice II west (see Figure 22).).

Figure 2. Situation of selected apartment building in map. Figure 2. Situation of selected apartment building in map. 2. Materials and Methods Many residents of prefabricated houses are reconstructing or renovating their apart- ments. As part of the renovation, some use the option to convert the balcony into a loggia. The reasons are varied: increased protection of children or personal intimacy, or prevention of excessive glare from the side walls of loggias. However, these facts have consequences Sustainability 2021, 13, x FOR PEER REVIEW 5 of 25

2. Materials and Methods Many residents of prefabricated houses are reconstructing or renovating their apartments. As part of the renovation, some use the option to convert the balcony into a loggia. The reasons are varied: increased protection of children or personal intimacy, or Sustainability 2021, 13, 3106 5 of 24 prevention of excessive glare from the side walls of loggias. However, these facts have consequences for the deterioration of daylight levels. Therefore, the purpose and goal is to compare the level of daylight in one apartment unit in Slovakia, in the town of Kosice, forHumenska the deterioration (street) 49, of where daylight two levels. rooms Therefore, have balconies, the purpose which and after goal modification is to compare will the be levelturned of daylightinto loggia ins one. apartment unit in Slovakia, in the town of Kosice, Humenska (street) 49, where two rooms have balconies, which after modification will be turned into loggias. 2.1. Description of the Selected Apartment 2.1. Description of the Selected Apartment In this study, two design variants were tested: two rooms with a balcony and two roomsIn with this study,a loggia. two Room design 1 variantsis south wereoriented. tested: Room two 4 roomsis east with oriented a balcony (see Figure and two 3). roomsThese are with south a loggia.- and Roomeast-facing 1 is southbalconies, oriented. which Room will be 4 istransformed east oriented into (see loggias Figure after3). Theserenovation. are south- Figure and 3 shows east-facing the layout balconies, of the which apartment will be in transformed a position such into as loggias the results after renovation.from the simulations Figure3 shows. This is the to layoutmake the of reader the apartment better oriented in a position in the suchtext to as have the resultsa better fromimage the of simulations.the situation. This is to make the reader better oriented in the text to have a better image of the situation.

Figure 3. plan of the apartment with the marking of test rooms. Figure 3. Floor plan of the apartment with the marking of test rooms. The tested rooms in the selected apartment building are illuminated by side and glassThe tested . rooms The following in the selected methodology apartment applies building in this are article:illuminated by side windows ­and glassMeasuring doors. theThe value following of daylight methodology in rooms applies in this article:  Measuring• with balcony, the value of daylight in rooms • with loggia,balcony, ­ Calculated with loggia, and simulated daylight situations, ­ CalculateConfrontationd and of simulated measured daylight and calculated situations, Daylight Factor (DF) values, ­ ConfrontationResults of daylight of measured simulations and forcalculated two alternatives Daylight withFactor balcony (DF) values, and loggia.  RecommendationsResults of daylight andsimulations conclusions. for two alternatives with balcony and loggia. ARecommendations view of the building and withconclusions. balconies before reconstruction and loggias after recon- struction can be seen in Figure4.

2.2. Research Methodology The description of individual steps in the evaluation of lighting conditions in the selected two rooms of the selected apartment in the Kosice II housing estate can be seen in the development diagram in Figure5. Sustainability 2021, 13, x FOR PEER REVIEW 6 of 25

Sustainability 2021, 13, 3106 6 of 24 A view of the building with balconies before reconstruction and loggias after reconstruction can be seen in Figure 4.

(a) view with balconies—south-oriented (b) view with balconies—east-oriented

(c) view with loggias—south-oriented (d) view with loggias—east-oriented

Figure 4. ViewView of the residential building ( a,b) before reconstruction—balconiesreconstruction—balconies and ((cc,,dd)) afterafter reconstruction—loggias.reconstruction—loggias.

2.2. Research Methodology Sustainability 2021, 13, x FOR PEER REVIEW 7 of 25

The description of individual steps in the evaluation of lighting conditions in the Sustainability 2021, 13, 3106 7 of 24 selected two rooms of the selected apartment in the Kosice II housing estate can be seen in the development diagram in Figure 5.

FigureFigure 5. 5. FlowchartFlowchart of of research research methodology. methodology. 2.3. Daylight Metrics 2.3. Daylight Metrics In the study, were calculated following daylight metrics: daylight factor, illuminance, In the study, were calculated following daylight metrics: daylight factor, illuminance, and uniformity. and uniformity.The Daylight Factor (DF) is a form of static daylight performance metric. It is widely usedThe and Daylight considered Factor as (DF) one ofis thea form simplest of static methods daylight to performance describe the amountmetric. It of is daylightwidely usedreceived and considered on a specific as pointone of in the a room.simplest The method minimums to describe and average the amount daylight of factors daylight for receivedrooms have on a been specific defined point as in 1.5% a room. and 3%, The respectively minimum [and30,31 average]. daylight factors for roomsThe have illuminance been defined (E) as is the1.5% amount and 3%, of lightrespectively falling on[30,31]. a surface per unit area, measured in lux.The illuminance It is measured (E) is at the work amount plane of height, light falling and directon a surface sunlight per is unit excluded area, measured from the incalculation. lux. It is measured Recommended at work average plane values height are, and 100–500 direct lux. sunlight is excluded from the calculation. Recommended average values are 100–500 lux. The uniformity (U0) is defined as the ratio of the minimum DF to the average DF within the space. The daylight uniformity ratio of the rooms was analyzed in order to investigate how the daylight was distributed in each space. Standards require a uniformity of 0.4. The authors used static metrics (DF) for the investigation. It is generally acknowledged that the standard daylight assessment method, used in this paper—the daylight factor— Sustainability 2021, 13, 3106 8 of 24

is being replaced by metrics based on absolute values of luminous quantities predicted throughout the year using sun and sky conditions derived from standardized climates. The move to more realistic daylighting measures represents a significant level of additional complexity both in the simulation of light quantities and in the reduction of simulation data to easy-to-understand metrics. The simulation component, at least for buildings with standard glazing materials, is reasonably well understood. However, there is no consensus on the composition of metrics, and their formulation is an ongoing area of active research. In addition, non-residential and residential buildings represent very different evaluation scenarios, and it is not yet entirely clear whether one metric could apply to both [51]. Residential architecture is one of the largest market segments in construction. How- ever, attention in the field of daylight simulation is surprisingly low. This raises the question of whether existing daylight metrics are suitable for design. In reference [52], a criti- cal check of current climate-based daylight metrics in the context of residential architecture is provided. It has been found that existing workflows often overlook relevant aspects of daylight in living spaces, such as daylight and seasonal availability of daylight and access to direct sunlight. Therefore, the concept of a new, annual climate-based assessment framework, called the daylight residential score, is being introduced to overcome these shortcomings. There are some dynamic metrics: - Useful Daylight Illuminance (UDI), but also - Spatial Daylight Autonomy Maximum (sDAmax) measures the percentage of floor area that receives daylight above the required illuminance, - Annual Sunlight Exposure(aSE) measures the percentage of floor area that receives more than a certain number of annual hours (typically 250) of direct light above a minimum threshold (typically 1000 lx), or other [51,52]: - Daylight Glare Index (DGI), - CIE Glare Index (CGI), - CIE Unified Glare Rating (UGR), - Daylight Glare Probability (DGP), - Direct Light Access (DLA), - Residential Daylight Autonomy (RDA) plots, - Residential Daylight Score (RDS). Most of them take as a basis direct sunlight and the time of year data for its action in a specific environment and building. However, our task is to objectify the effect of the modification of the balconies on the loggias and to express what changes this will cause in the interior lighting under cloudy skies. This means only diffuse daylight is taken into account.

3. Case Study—Rooms in Residential Building The elected residential building is located in the city of Kosice—west. The residential house is built in a panel construction system type T06B, which has a load-bearing system formed of reinforced concrete walls axially spaced by 3600 mm. A protruding perimeter cladding of aerated concrete is suspended on the load-bearing walls. The house in the lon- gitudinal direction has a three-story road. Perpendicular to the middle tract symmetrically from both sides are transverse walls with a modulus of 3.6 m. One part of the terraced building (expansion unit) usually consists of five modules with a span of 3.6 m. The house has seven floors. The evaluated rooms of the residential building used in the case study are located on the fifth floor of this selected building.

3.1. Daylight Calculations Measurements were performed in selected rooms in Kosice (see Figure2). South- oriented testing rooms on the fifth floor with interior dimensions 3.43 m × 3.67 m × 2.70 m (Room 1) and 4.78 m × 3.43 m × 2.70 m (Room 4) were selected (see Figure6). The height of the parapet in both rooms is 900 mm. Side-window dimensions are 1200 mm × 1450 mm and the size of the balcony window is 850 mm × 2250 mm (Room 1). Room 4, side- Sustainability 2021, 13, x FOR PEER REVIEW 9 of 25

m. The house has seven floors. The evaluated rooms of the residential building used in the case study are located on the fifth floor of this selected building.

3.1. Daylight Calculations Measurements were performed in selected rooms in Kosice (see Figure 2). South- oriented testing rooms on the fifth floor with interior dimensions 3.43 m × 3.67 m × 2.70 m (Room 1) and 4.78 m × 3.43 m × 2.70 m (Room 4) were selected (see Figure 6). The height of the parapet in both rooms is 900 mm. Side-window dimensions are 1200 mm × 1450 mm and the size of the balcony window is 850 mm × 2250 mm (Room 1). Room 4, side- window dimensions are 1200 mm × 1450 mm and the size of the balcony window is 850 mm × 2250 mm. The fenestration systems were made of double glazing in plastic frame. For calculations, the following coefficients were considered: transmittance coefficient 0.8, maintenance factor of glazing on the exterior surface 0.9, maintenance factor of glazing on the interior surface 0.85, reflectance factor of the ground 0.15 (dark ground). In all tested rooms, the color of the was white, the reflectance factor was 0.7, and the reflectance factor of the floor was 0.45. In Room 1, the walls were orange, with a reflectance factor of 0.20. In Room 4, the walls were yellow, with a reflectance factor of 0.30 (see Table 1). The window-to-wall ratio is 9.86% (Room 1) and 10.40% (Room 4) (see Table 2). The working plane was 0.85 m high (desk height). The light loss coefficient due to window Sustainability 2021, 13, 3106 9 of 24 construction was τ = 0.64. Neighboring objects did not shade the rooms. With the given lighting system, at the critical point of the functional place on the horizontal plane, the following values were required: minimum standard value of daylight factor, DFmin = 0.5% windowto 1.5%; average dimensions daylight are 1200 factor mm, DF×average1450 = mm1.5% and to 3% the; and size uniformity of the balcony of illumination window is 850more mm than× 22500.4 for mm. given a visual task [53,54].

(a) (b)

FigureFigure 6.6. InteriorInterior ofof residentialresidential buildingbuilding ((aa)) simulatedsimulated modelmodel ofof RoomRoom 1:1: south-oriented;south-oriented; (b)) simulatedsimulated modelmodel of RoomRoom 4:4: east-oriented.east-oriented.

TableThe 1. Characteristic fenestration parameters systems were of surfaces. made of double glazing in plastic frame. For calcula- tions, the following coefficients were considered: transmittance coefficient 0.8, maintenance factor of glazing on the exterior surface 0.9, maintenanceReflectance factor of glazing (%) on the interior surface 0.85, reflectanceceiling factor of the ground 0.15 (dark ground).70 In all tested rooms, the color of the ceilingsfloors was white, the reflectance factor was 0.7, and45 the reflectance factor of the floor waswall 0.45.—orange In Room 1, the walls were orange, with a20 reflectance factor of 0.20. In Room 4, thewall walls—yellow were yellow, with a reflectance factor of30 0.30 (see Table1). The window-to-wall ratio is 9.86% (Room 1) and 10.40% (Room 4) (see Table2). The working plane was 0.85 m high (desk height). The light loss coefficient due to window construction was τ = 0.64. Neighboring objects did not shade the rooms. With the given lighting system, at the critical point of the functional place on the horizontal plane, the following values were required: minimum standard value of daylight factor, DFmin = 0.5% to 1.5%; average daylight factor, DFaverage = 1.5% to 3%; and uniformity of illumination more than 0.4 for given a visual task [53,54].

Table 1. Characteristic parameters of surfaces.

Reflectance (%) 70 floors 45 wall—orange 20 wall—yellow 30

Table 2. Window–wall ratio (WWR) and window–floor ratio (WFR).

Window–Wall Window–Floor Area (m2) Window Area (m2) Walls Ratio Ratio Room 1 3.78 38.34 0.099 0.300 Room 4 3.74 35.95 0.104 0.227 Sustainability 2021, 13, x FOR PEER REVIEW 10 of 25

Table 2. Window–wall ratio (WWR) and window–floor ratio (WFR).

Area (m2) Area (m2) Window Window–Wall Ratio Window–Floor Ratio Walls Room 1 3.78 38.34 0.099 0.300 Room 4 3.74 35.95 0.104 0.227

3.2. Daylight Measurements A minimum illumination of 300 lx is recommended for most of the room area meeting the target climate-based daylight factor and 500 lx for the areas where productive work is performed. On the selected day, the value of the outside light ranged from 2000 to 5000 lx in January. Measurement was performed at control points simultaneously with two lux meters (see Figure 7). An exterior horizontal illumination of 5000 lx was considered for the simulation program [53,54]. The instruments used for measurement were two data loggers, ALMEMO 2690-10A, and an illuminance sensor ALMEMO FLA 623VL with the production number 15,061,543, and accuracy of 5%. Despite the fact that the manufacturer of this device provides this information on their catalog card, this information is not correct in terms of illuminometer metrology. It is not possible to determine the measurement error of the overall lighting instrument without knowing the spectral distribution of the measured light source [55,56]. Various measurement procedures can be found in the literature and can also be affected by the influence of different photometric observers on the accuracy of the lux meter [57], the spectral correction of the detector used to measure the illumination [58], the register for evaluating the general photometric performance of photometers [59], and the relationship between measurement error and photometer power index [60]. Using Sustainability 2021, 13, 3106 artificial lighting influences of the quality of the spectral response of the photometric10 of 24 detector on the correction factors of the spectral mismatch of the white LED [61]. In Slovakia, the standard ČSN 12464-1 applies to the lighting of workplaces [62]. A more detailed procedure of workplace lighting with a measurement methodology can be found 3.2. Daylight Measurements in reference [63]. TheA minimum measurement illumination methodology of 300 lx isin recommendedthis case was for followed most of theaccording room area to meetingSlovak standardthe target “Measurements climate-based daylight of daylighting” factor and 500 [64]. lx for A themore areas precise where description productive work of the is measurementperformed. On methodology the selected day, is also the in value the ofliterature the outside, e.g., light Darula ranged [65]. from A description 2000 to 5000 of lx thein January.entire metho Measurementdology was was published performed by at controlthe authors points in simultaneously Building and Environment with two lux [66]meters last (see year. Figure 7). An exterior horizontal illumination of 5000 lx was considered for the simulation program [53,54].

Room 1 Room 4

Figure 7. Situation—floorplan of rooms and control points for measurements and calculations.

The instruments used for measurement were two data loggers, ALMEMO 2690-10A, and an illuminance sensor ALMEMO FLA 623VL with the production number 15,061,543, and accuracy of 5%. Despite the fact that the manufacturer of this device provides this information on their catalog card, this information is not correct in terms of illuminometer metrology. It is not possible to determine the measurement error of the overall lighting instrument without knowing the spectral distribution of the measured light source [55,56]. Various measurement procedures can be found in the literature and can also be affected by the influence of different photometric observers on the accuracy of the lux meter [57], the spectral correction of the detector used to measure the illumination [58], the register for evaluating the general photometric performance of photometers [59], and the relationship between measurement error and photometer power index [60]. Using artificial lighting influences of the quality of the spectral response of the photometric detector on the correction factors of the spectral mismatch of the white LED [61]. In Slovakia, the standard CSNˇ 12464-1 applies to the lighting of workplaces [62]. A more detailed procedure of workplace lighting with a measurement methodology can be found in reference [63]. The measurement methodology in this case was followed according to Slovak stan- dard “Measurements of daylighting” [64]. A more precise description of the measurement methodology is also in the literature, e.g., Darula [65]. A description of the entire method- ology was published by the authors in Building and Environment [66] last year.

3.3. Comparison of Measurement and Simulation Results Daylighting simulations were performed by DIAlux evo 9.1 with the model of tested rooms and two variants (balcony and loggia). The results of measured values of illuminance (E) and calculated DF from measured values can be seen in Tables3 and4 and Figure8. Sustainability 2021, 13, 3106 11 of 24

Table 3. Results of daylight factor (DF, %) from measured values.

DFmin DFmax DFaverage U0 Room 1—balcony 0.60 4.74 1.82 0.33 Room 1—loggia 0.25 2.72 0.95 0.26 Room 4—balcony 1.00 3.50 1.70 0.59 Room 4—loggia 0.55 3.15 1.53 0.36 Normed 1.50 - - 0.40

Table 4. Results of measured values of illuminance (E, lx).

Emin Emax Eaverage Room 1—balcony 20 142 55 Room 1—loggia 12 90 25 Room 4—balcony 45 150 76 Room 4—loggia 25 100 60 Normed 100—500 - -

(a) Illuminance Emin Emax Eaverage 160 150 142 140

120 100 100 90 76 80 60 55 60

45 Illuminance (lx) 40 25 25 20 20 12

0 Room 1 - balcony Room 1 - loggia Room 4 - balcony Room 4 - loggia

(b)

FigureFigure 8.8. Results of (aa)) daylight factor (DF,(DF, %)%) ((bb)) illuminanceilluminance (E,(E, lx)lx) fromfrom measuredmeasured values. values.

1

Sustainability 2021, 13, x FOR PEER REVIEW 12 of 25

Table 4. Results of measured values of illuminance (E, lx).

Emin Emax Eaverage Room 1—balcony 20 142 55 Room 1—loggia 12 90 25 Room 4—balcony 45 150 76 Sustainability 2021, 13, 3106 Room 4—loggia 25 100 12 of 2460 Normed 100—500 - - The results of simulated values for DF and illuminance can be seen in Table 5 and Figures 9 and 10. Isolines with the same illumination and DF can be seen in Figures 11– The results14. of simulated values for DF and illuminance can be seen in Table5 and Figures9 and 10. Isolines with the same illumination and DF can be seen in Figures 11–14. Table 5. Results of DF calculated by the simulation program. Table 5. Results of DF calculated by the simulation program. DFmin DFmax DFaverage U0

Room 1—balconyDF min DF0.43max DF3.21average 1.32U 0 0.33 Room 1—loggia 0.31 1.51 0.63 0.49 Room 1—balcony 0.43 3.21 1.32 0.33 Room 1—loggiaStandard deviation 0.31 1.510.06 0.85 0.63 0.35 0.49 Standard deviationRoom 4—balcony 0.06 0.850.32 2.18 0.35 0.95 0.34 Room 4—balconyRoom 4—loggia 0.32 2.180.08 1.91 0.95 0.75 0.34 0.11 Room 4—loggiaStandard deviation 0.08 1.910.12 0.14 0.75 0.10 0.11 Standard deviation 0.12 0.14 0.10

Sustainability 2021, 13, x FOR PEER REVIEW 13 of 25

(a)

(b)

Figure 9. ResultsFigure 9. of Results simulated of simulated values values of (a) DFof (a (%)) DF and (%) (andb) illuminance—Room (b) illuminance—Room 1. 1.

(a) Sustainability 2021, 13, x FOR PEER REVIEW 13 of 25

Sustainability 2021, 13, 3106 13 of 24 (b) Figure 9. Results of simulated values of (a) DF (%) and (b) illuminance—Room 1.

Sustainability 2021, 13, x FOR PEER REVIEW 14 of 25

(a)

(b)

Figure 10. FigureResults 10. of Results simulated of simulated values ofvalues (a) DF of ( (%)a) DF and (%) ( band) illuminance (b) illuminance (lx)—Room (lx)—Room 4. 4.

Figures 11c, 12c, Figures13c and 11 14c, c,12 showc, 13c and graphical 14c, show dependences graphical dependences of simulated of simulated DF results DF results in in the section of thethe consideredsection of the rooms considered at the rooms considered at the considered points 1, points 2, 3, 4,1, 2, 5 in3, 4, individual 5 in individual rows A, B, C, D, E. It is interesting to see the decrease of DF, where it is clearly shown that in rows A, B, C, D, E. It is interesting to see the decrease of DF, where it is clearly shown that some places closer to the perimeter wall the DF values are lower when the position of in some places closerobserved to the points perimeter is at a greater wall the distant DF values from the are wall. lower when the position of observed points is at aIn greater addition distant to these from already the wall. presented results, the influence of color, position, and In addition toglazing these was already investigated presented in all results, cases. The the results influence are interesting. of color, position, and glazing was investigatedAlthough in all cases. some authorsThe results report are achieving interesting. a significant change in the indoor light Although someclimate authors by applying report different achieving colors a on significant the loggiachange walls, in inour the observation indoor light, these changes climate by applyingwere different not significant. colors on Due the to loggia the fact walls, that diffuse in our light observation, is considered, these the changes influence of the were not significant.color Due of the to loggia the fact walls that on diffusethe lighting light conditions is considered, in the interior the influence was minimal. of the The values color of the loggiaof walls the daylight on the lightingfactor changed conditions only in in hundreds. the interior was minimal. The values of the daylight factor changedFrom this only, it can in be hundreds. concluded that the influence of the color of the loggia walls on the conditions of DF in the interior is not large. This result was achieved in both rooms. Interestingly, when only balcony boards (not loggias) were considered, the effect on the world is visible. Due to the influence of the reinforced concrete console of the slab above the apartment—in the orientation to the south (for Room 1) there is a difference for DFmin 11% and in the orientation to the cardinal—the east (places for Room 4) there is a difference for DFmin of up to 33%. In the graphs, parts of Figures 11a, 12ac, 13a and 14ac represent the level of daylight on the work plane in Rooms 1 and 4 in lux. In the graphs, parts of Figures 11b, 12b, 13b and 14b represent the level of daylight on the work surface in Rooms 1 and 4, shown as DF (%). SustainabilitySustainability 20212021,, 1313,, x 3106 FOR PEER REVIEW 1514 of of 25 24

(a) (b) 3.5

3 y = −1.697ln(x) + 1.9487 ROOM 1 - BALCONY

2.5

2

DF (%) DF 1.5

1

0.5 y = −0.2286x2 + 0.4457x + 0.64 0 0 0.5 1 1.5 2 2.5 3 Distance from the window (m)

(c)

FigureFigure 11. 11. ResultsResults of of ( (aa)) illuminance illuminance (lx) (lx) and and ( (bb)) daylight daylight factor factor (%) (%),, Room Room 1 1—with—with balcony; balcony; and and ( (cc)) the the decrease decrease of of the the DF DF atat points points remote remote from from the the transparent transparent structure. From this, it can be concluded that the influence of the color of the loggia walls on the conditions of DF in the interior is not large. This result was achieved in both rooms. Interestingly, when only balcony boards (not loggias) were considered, the effect on the world is visible. Due to the influence of the reinforced concrete console of the slab above the apartment—in the orientation to the south (for Room 1) there is a difference for DFmin 11% and in the orientation to the cardinal—the east (places for Room 4) there is a difference for DFmin of up to 33%. In the graphs, parts of Figures 11a, 12ac, 13a and 14ac represent the level of daylight on the work plane in Rooms 1 and 4 in lux. In the graphs, parts of Figures 11b, 12b, 13b and 14b represent the level of daylight on the work surface in Rooms 1 and 4, shown as DF (%). Sustainability 2021, 13, 3106 15 of 24

Sustainability 2021, 13, x FOR PEER REVIEW 16 of 25 The results for the change in the area of the translucent surfaces (window area) can be seen in Figure 15.

(a) (b) 2.5

y = 2.7528e−0.539x 2 ROOM 4 - BALCONY

1.5 DF (%) DF 1

0.5 y = 0.2286x2 − 0.5257x + 0.54

0 0 0.5 1 1.5 2 2.5 3 Distance from the window (m)

(c)

FigureFigure 12.12. ResultsResults ofof ((aa)) illuminanceilluminance (lx)(lx) andand ((bb)) daylightdaylight factorfactor (%),(%), RoomRoom 4—with4—with balcony;balcony; andand ((cc)) decreasedecrease ofof thethe DFDF atat pointspoints remoteremote fromfrom thethe transparenttransparent structure. structure. Sustainability 2021, 13, 3106 16 of 24 Sustainability 2021, 13, x FOR PEER REVIEW 17 of 25

(a) (b)

1.6

y = −0.562ln(x) + 1.109 1.4 ROOM 1 - LOGGIA

1.2

1

0.8 DF (%) DF 0.6

0.4 y = −0.0238x2 + 0.0595x + 0.3714 0.2

0 0 0.5 1 1.5 2 2.5 3 3.5 4 Distance from the window (m)

(c)

Figure 13. Results of (a) illuminanceilluminance (lx) and (b) daylightdaylight factor (%),(%), Room 1—with1—with loggia;loggia; and (c) decrease of the DF at points remote from thethe transparenttransparent structure.structure. Sustainability 2021, 13, 3106 17 of 24 Sustainability 2021, 13, x FOR PEER REVIEW 18 of 25

(a) (b)

2.1 0.5 1 1.5 1.7 1.6 2 1.4 2.5

1.2 3 DF (%) DF 1.0 1.1 1.1 0.9 0.8 0.8 0.7 0.7 0.7 0.6 0.6 0.5 0.4 0.3 0.3 0.2 0.2 0.2 0.2 0.2 0.2 0.1 0.5 1 1.5 2 2.5 3 0.5 1.7 2.1 1.2 0.6 0.2 0.1 1 1.4 1.6 1.1 0.6 0.2 0.1 1.5 1 1.1 0.9 0.6 0.3 0.2 2 0.2 0.2 0.2 0.2 0.2 0.2 2.5 0.8 0.8 0.7 0.5 0.3 0.2 3 0.7 0.7 0.6 0.4 0.3 0.3 Distance from the window (m)

(c)

FigureFigure 14. 14.Results Results of of (a ()a illuminance) illuminance (lx) (lx) and and ((bb)) daylightdaylight factor (%) (%),, Room Room 4 4—with—with loggia loggia;; (c ()c decrease) decrease of ofthe the DF DF at points at points remote from the transparent structure. remote from the transparent structure. Sustainability 2021, 13, 3106 18 of 24

The height of the window is the same in both Room 1 and Room 4, i.e., 1200 mm, with a windowsill height of 900 mm. If we widened the window by 100 mm, we would get different results in cloudy skies, but the difference is not so great. The effect of the window area was measured by changing the width of the windows in both rooms. The average DF naturally shows the biggest difference in the balcony in Room 1 and it varies from 1.32 to 1.95. The smallest differences are in the same room, if instead of a balcony there is a loggia. The difference is very small; the average DF is from 0.63 to 0.79. The same situation is repeated for DFmax. This is achieved again in Room 1 with a Sustainability 2021, 13, x FOR PEER REVIEWbalcony and the smallest difference is in the same room with the loggia. Another19 is of the 25

setting with minimum DF values. Although the minimum DF value varies from 0.43 to 0.56, the smallest difference in the minimum DF is achieved in Room 4 with a loggia, i.e., fromThe 0.08 results to 0.15. for The the classificationchange in the of area these of roomsthe translucent into lighting surfaces classes (window depends area) on can the beactivity seen in performed. Figure 15.

(a) DF average (%) 2.5 Balcony 1 Loggia 1 Balcony 4 Loggia 4 average 2

1.5

1 DF average (%) average DF 0.5

0 1200 1300 1400 1500 1600 Width of window structure (mm)

(b) DF max (%) 6 Balcony 1 Loggia 1 Balcony 4 Loggia 4 opt 5

4

3

DF max (%) max DF 2

1

0 1200 1300 1400 1500 1600 Width of window structure (mm)

Figure 15. Cont. Sustainability 2021, 13, 3106 19 of 24 Sustainability 2021, 13, x FOR PEER REVIEW 20 of 25

(c) DF min (%) 0.7 Balcony 1 Loggia 1 Balcony 4 Loggia 4 standard 0.6

0.5

0.4

DF (%) DF 0.3

0.2

0.1

0 1200 1300 1400 1500 1600 Width of window structure (mm)

Figure 15. Results ofof DFDF (%)(%) forfor RoomsRooms 1, 1, 4 4 ( a(a)) DF DFaverageaverage,,( (b) DF max, ,((cc)) DF DFminmin, and, and for for rooms rooms before before and and after after reconstruction reconstruction..

4. DiscussionThe height of the window is the same in both Room 1 and Room 4, i.e., 1200 mm, with Thisa windowsill study examines height theof 900 feasibility mm. If ofwe renovating widened the balconies window into by loggias 100 mm, to assesswe would day- getlight. differ Theent evaluation results in of cloudy daylight skies, availability but the difference was performed is not forso bothgreat. alternatives The effect of using the windowmeasurements area was and measured a series ofby computer changing simulationsthe width of DIAluxthe windows evo 9.1. in Theboth resultsrooms.of this studyThe were average evaluated DF naturally in terms shows of daylight the biggest factor difference and lighting in the levels balcony of thein Room residential 1 and itbuilding varies fro accordingm 1.32 to to 1.95. daylight The standards.smallest differences The daylight are in factor the same is comparable room, if instead in measure- of a balconyments and there calculations. is a loggia. Boundary The difference conditions is very were small; also the found average in the DF measurements, is from 0.63 to which 0.79. wereThe same entered situation as inputs is repeated to computer for DF simulations.max. This is achieved The DF resultsagain in were Room compared 1 with a withbalcony the andDF valuethe smallest standard. difference The results is in the show same that room DF, with both the on loggia. balconies Another and loggias, is the setting meets with the minimumexpected values DF values. only in Although close proximity the minimum to the glazed DF value areas. varies from 0.43 to 0.56, the smallestThe difference results show in the exactly minimum that DF if the is achieved measured in valuesRoom 4 have with aa DFloggia value, i.e., below from 0.08 the tostandard 0.15. The level classification (especially DF ofmin these), in the rooms case into of simulations lighting classes they have depends DF values on the also activity below performed.the standard. The distribution of the simulated DF values on the observation plane is shown in the Figures 11–14. When comparing the measured and normalized values, it can 4.be Discussion stated that the DFmin value is not met, but the values for the balconies are twice as high as those for the loggia. This study examines the feasibility of renovating balconies into loggias to assess In addition to the DF, the lighting level was taken into account in this study. The daylight. The evaluation of daylight availability was performed for both alternatives analysis of the lighting level shows the well-known fact that a higher lighting level is using measurements and a series of computer simulations DIAlux evo 9.1. The results of located at the windows and in the rooms with balconies. After the restoration of the this study were evaluated in terms of daylight factor and lighting levels of the residential balconies to the loggia, the level of lighting in the middle of the room will be reduced building according to daylight standards. The daylight factor is comparable in by almost 50%, while on the sides of the room this level does not reach even 30% of the measurementsoriginal lighting. and The differences calculations. in Rooms Boundary 1 and conditions 4 are slight. were also found in the measurements,For the resulting which comparisonwere entered of as the inputs decrease to computer of the daylight simulations. factor The in the DF distance results werefrom thecompared windows, with the the graphs DF value in Figures standard. 11c, The12c, r13esultsc and show 14c were that drawnDF, both in orderon balconies to plot andthe graphicloggias, dependences.meets the expected In Room values 1 with only a balconyin close inproximity row “C” to of the the glazed observation areas. points, whichThe is in results the middle show ofexactly the room that through if the measured the window, values the have line is a logarithmic, DF value below while the in standardrow “E” closelevel to(especially the wall itDF ismin square), in the (see case Figure of sim 11ulations). The same they curvaturehave DF values can be also observed below thein Room standard. 1 if the The balcony distribution is changed of the to simulated a loggia, except DF values that the on DF the values observation drop by plane about is shownhalf (see in Figure the Figures 13). In 11 Room to 14. 4, When the situation comparing is different. the measured If there and is a normalized balcony in thevalues, room, it canthe resultsbe stated can that be the compared DFmin value to those is not achieved met, but in the Room values 1 only for the in thebalconies plane throughare twice the as highcenter as of those the window,for the loggia. where the graphical dependence is exponential, and in places close to theIn side addition wall as to well the asDF, in the Roomlighting 1 quadratic level was (see taken Figure into 12 account). If a balcony in this isstudy. created The in analysis of the lighting level shows the well-known fact that a higher lighting level is located at the windows and in the rooms with balconies. After the restoration of the Sustainability 2021, 13, x FOR PEER REVIEW 21 of 25

balconies to the loggia, the level of lighting in the middle of the room will be reduced by almost 50%, while on the sides of the room this level does not reach even 30% of the original lighting. The differences in Rooms 1 and 4 are slight. For the resulting comparison of the decrease of the daylight factor in the distance from the windows, the graphs in Figures 11c, 12c, 13c and 14c were drawn in order to plot the graphic dependences. In Room 1 with a balcony in row “C” of the observation points, which is in the middle of the room through the window, the line is logarithmic, while in row “E” close to the wall it is square (see Figure 11). The same curvature can be observed in Room 1 if the balcony is changed to a loggia, except that the DF values drop by about half (see Figure 13). In Room 4, the situation is different. If there is a balcony in the room, the results can be compared to those achieved in Room 1 only in the plane through the Sustainability 2021, 13, 3106 20 of 24 center of the window, where the graphical dependence is exponential, and in places close to the side wall as well as in the Room 1 quadratic (see Figure 12). If a balcony is created in Room 4, the results do not represent any functional dependence (see Figure 14). Near theRoom window, 4, the resultsthe DFs do are not smaller represent than any in more functional distant dependence places. (see Figure 14). Near the window,Comparing the DFs arethe smaller results than in Rooms in more 1 distant and 4 places. with balconies and loggias is quite interesting.Comparing Figure the 16 results shows in Rooms the results 1 and only 4 with forbalconies the center and ofloggias the transparent is quite interesting. opening (centFigureer 16of theshows room) the at results the observed only for height the center at the of distances the transparent given in opening the previous (center sections of the. Forroom) Room at the 1 with observed balconies, height it atcan the be distances seen that giventhe daylight in the previous factor drops sections. sharply For from Room the 1 window,with balconies, the resulting it can be line seen acquires that the an daylight exponential factor character. drops sharply This is fromdescribe thed window, by the blue the equation.resulting lineThe acquiresdaylight an factor exponential in Room character. 4 with a balcony This is described has a similar by the course blue equation.as in Room The 1. Thedaylight slope factor of the in line Room drop 4 withis smaller, a balcony but the has course a similar is also course close as to in the Room exponential 1. The slope equation of the (redline dropequation). is smaller, The situation but the course is different is also when close applying to the exponential a loggia. When equation creating (red equation). partition wallsThe situation on both sides is different of the balcony when applying (left and a right), loggia. the When course creating of the daylight partition factor walls decrease on both issides different. of the balconyFinally, when (left and looking right), for the a coursefunctional of the dependence daylight factor in Room decrease 1 with is different.a loggia, theFinally, course when of the looking decline for is a logarit functionalhmic dependence(green equation) in Room, and 1the with situation a loggia, in theRoom course 4 with of athe loggia decline is quite is logarithmic complicated. (green Near equation), the window, and thethe situationDF is higher in Room than 4at with a more a loggia distant is point.quite complicated. From a distance Near of the about window, 1.5 them, thereDF is higheris already than a at normal a more decrease distant point. in daylight. From a Finally,distance whenof about testing 1.5 m, mul theretiple is already possibilities, a normal the decrease functional in daylight. dependence Finally, in when this casetesting is quadraticmultiple possibilities, (yellow line theand functional yellow equation). dependence These in thisresults case show is quadratic that the (yellow loggias line are andnot yellow equation). These results show that the loggias are not successful in introducing light successful in introducing light into the room. The numbers for lighting levels are still into the room. The numbers for lighting levels are still below the standard. below the standard.

Comparison of the results of Rooms 1 and 4 with balcony or with loggia

3.5 1-balcony 3.2 4-balcony 3 1-loggia y = 4.3561e−0.313x 4-loggia 2.5 2.5 y = 2.5465e−0.178x 2 2.1 1.7 1.7 DF (%) DF 1.5 1.2 1 1.1 0.9 y = −0.562ln(x) + 1.4983 0.7 0.6 0.5 0.5 0.4 0.3 y = 0.0274x2 − 0.5369x + 2.5286 0.2 0 0 1 2 3 4 5 6 7 8 Distance from the balcony or from the loggia (m) measured points

Figure 16. Results of DF (%) for Rooms 1, 4 (blue line—Room 1 with balcony), (red line—Room 4 with balcony), (green line—Room 1 with loggia), (yellow line—Room 4 with loggia).

In further research, three influences on the level of DF after the change from a balcony to a loggia were observed. They were a change in the color of the loggia walls, the position to the cardinal, and the influence of the size of the glass part in the front wall, separating the room from the balcony (loggia). As already mentioned, the colors of the loggia walls do not have a significant effect on the resulting DF. The greater influence is the orientation of the room to the cardinal. Even though it is a cloudy sky, the brightness of the sky will increase or decrease the DF by 11% to 33%. The effect of the change of glazed surfaces on the resulting DF in the observed rooms is interesting in that this effect is different for balconies and loggias. In rooms with balconies, DFmin, DFmax, and DFaverage also increase by increasing the window area. In loggia rooms, Sustainability 2021, 13, 3106 21 of 24

these values are almost parallel lines (see Figure 15), indicating that these resulting values of DFmin, DFmax, and DFaverage vary very little. The impact of balconies or loggias is small for the evaluation criteria. The good level of lighting was analyzed on the basis of the requirements for residential buildings according to national standards. The highest measured interior lighting at the farthest point was about 30–50 lx, which is below the standard value of 100 lx. In both models, daylight reached high levels in areas near the windows and was reduced along the entire length of the room. However, DFmin values were not reached for half of the room length.

5. Conclusions In modern society, people spend most of their time indoors—the so-called indoor generation. This is especially true for this period of the pandemic, COVID-19, when in many countries there is a state of emergency, and it is not possible to go out. Daylight has a positive effect on human health and well-being. We can get daylight into the interior with transparent fillings. In this case, the visual connection of windows with the exterior through protruding elements from the facade of balconies and loggias was considered. The quality of lighting depends on many factors. People in many countries live in apartment block houses, where almost every apartment has a balcony or loggia. Reconstruction of balconies and loggias is one of the basic components of the renovation of apartment buildings. Balconies and loggias are a complex part of building design and provide considerable benefits to residential buildings. Going to the balcony is sometimes the only way to get outside for fresh air. The aim of the study was to evaluate and compare the daylight availability in rooms with balconies and with loggias. The article compares two alternatives of façade elements: before reconstruction, with balconies, and after reconstruction, with loggias. The construc- tion of the loggia adds to the building a different value in terms of architecture compared to the balcony. In terms of the entry of daylight into the interior, it is not the same case. The results show that the influence of loggias reduces the daylight factor by about half compared to the balconies. In this study, a simulation program was utilized for models of rooms with balconies and loggias when considering the cloudy sky. The results of this study show the impact of balconies and loggias in residential buildings and their use for similar studies. The results from measurements show that the indoor light levels in rooms for both variants are below the standard. The daylight was insufficient to provide good illuminance, and the light was not uniformity distributed. The analysis showed that the balconies bring better results in letting daylight into the rooms compared to the loggias, but even these do not meet the required level of daylight (due to the top plate of the balcony in the apartment above). Reconstruction of the balconies improved the static and thermal properties but worsened the lighting conditions. If we separate the balcony from the exterior on the right and from the left by a wall, we will create a safer space (loggia), but it will be worse for lighting conditions. We tried to graphically show the course of the decrease of the level of the daylight factor in the sections of the considered rooms. The results show that the decrease in the lighting level is different at the control points. Depending on how far the checkpoint is. In Room 1 it was a decrease of 30–50%, while in Room 4 it was from 40% to almost 70%. Therefore, when modifying the balcony to a loggia, it is necessary to keep these facts in mind. It is necessary to remember this and do everything we can to ensure safety and sustainability when using these spaces. As already mentioned, we must protect these areas, because sometimes these are the only areas where the occupant can be in contact with the outside environment. Sustainability 2021, 13, 3106 22 of 24

Author Contributions: Conceptualization, E.D. and D.K.; methodology, D.K.; software, E.D.; valida- tion, B.D.; formal analysis, Z.M.; investigation, B.D.; resources, Z.M.; data curation, E.D.; writing— original draft preparation, E.D. and D.K.; writing—review and editing, Z.M.; visualization, E.D.; supervision, E.D. and D.K.; project administration, D.K.; funding acquisition, D.K. All authors have read and agreed to the published version of the manuscript. Funding: This paper was elaborated with the financial support of the research projects VEGA 1/0674/18 and VEGA 2/0017/20 of the Scientific Grant agency, the Ministry of Education, Science, Research, and Sport of the Slovak Republic and the Slovak Academy of Sciences. Institutional Review Board Statement: Not applicable. Informed Consent Statement: Not applicable. Data Availability Statement: Not applicable. Conflicts of Interest: The authors declare no conflict of interest.

References 1. Cheong, C.H.H.; Kim, T.; Leigh, S.B. Thermal and daylighting performance of energy-efficient windows in highly glazed residential buildings: Case study in Korea. Sustainability 2014, 6, 7311–7333. [CrossRef] 2. Ali, M.A.D.; Daeung, D.K. A study of design variables in daylight and energy performance in residential buildings under hot climates. Energies 2020, 13, 5836. [CrossRef] 3. Westermann, K. Future Generations Face Health Risk from Life Indoors. Velux Media Centre, 2018. Available online: https: //press.velux.com/future-generation-of-brits-faces-health-risks-from-life-indoors/ (accessed on 24 January 2021). 4. Westermann, K. Daylight Affects People’s Sleep and Productivity, According to Global Survey. Velux Media Centre, 2018. Available online: https://press.velux.com/daylight-affects-peoples-sleep-and-productivity-according-to-global-survey/ (accessed on 24 January 2021). 5. Westermann, K. Are You Feeling Blue? Velux Media Centre, 2019. Available online: https://press.velux.com/are-you-feeling- blue/ (accessed on 24 January 2021). 6. Sehar, A.; Priyadarsini, R. Investigating daylight in the apartment buildings in Melbourne. Infrastructures 2020, 5, 81. [CrossRef] 7. Kristensen, P.E. Daylighting technologies in non-domestic buildings. Int. J. Sol. Energy 1994.[CrossRef] 8. Mohapatra, B.N.; Kumar, M.R.; Mandal, S.K. Analysis of daylighting using daylight factor and luminance for different room scenarios. Int. J. Civ. Eng. Technol. 2018, 9, 949–960. Available online: http://www.iaeme.com/IJCIET/index.asp (accessed on 24 January 2021). 9. Li, D.H.W. A review of daylight illuminance determinations and energy implications. Appl. Energy 2010, 87, 2019–2118. [CrossRef] 10. Schulzova, K.; Bošova, D. The quality of daylight in various types of residential buildings. EnviBuild 2019, 2019.[CrossRef] 11. Gochenour, S.J.; Andersen, M. Circadian effects of daylighting in a residential environment. Proc. IBPSA Conf. 2013, 70, 138–149. Available online: https://infoscience.epfl.ch/record/153689 (accessed on 25 January 2021). 12. Reinhart, C.F.; Fitz, A. Findings from a survey on the current use of daylight simulations in building design. Energy Build. 2006, 38, 824–835. [CrossRef] 13. Šprah, N.; Košir, M. Daylight provision requirements according to EN 17037 as a restriction for sustainable urban planning of residential developments. Sustainability 2019, 12, 315. [CrossRef] 14. Ribeiro, C.; Ramos, N.M.M.; Flores-Colen, I. A review of balcony impacts on the indoor environmental quality of dwellings. Sustainability 2020, 12, 6453. [CrossRef] 15. Simm, S.; Coley, D. The relationships between wall reflectance and daylight factor. Architectural Sci. Rev. 2011, 54, 329–334. [CrossRef] 16. Lee, J.; Boubekri, M.; Liang, F. Impact of building design parameters on daylighting metrics using an analysis, prediction, and optimalization approach based on statistical learning technique. Sustainability 2019, 11, 1474. [CrossRef] 17. Cheung, H.D.; Chung, T.M. A study on subjective preference to daylit residential indoor environment using conjoint analysis. Build. Environ. 2008, 43, 2101–2111. [CrossRef] 18. Dogan, T.; Ye Chan, P. A new framework for residential daylight performance evaluation. In Proceedings of the Lux Europa 2009—11th European Lighting Conference, San Francisco, CA, USA, 7–9 August 2017. [CrossRef] 19. Aries, M.B.C.; Aarts, M.P.J.; Van Hoof, J. Daylight and health: A review of the evidence and consequences for the built environment. Light. Res. Technol. 2013, 47, 6–27. [CrossRef] 20. Edward, L.; Torcellini, A. A Literature review of the effects of natural light on building occupants. Natl. Renew. Energy Lab. Tech. Rep. 2002, 17–26. [CrossRef] 21. Ashrafian, T.; Moazzen, N. The impact of glazing ratio and window configuration on occupants’ comfort and energy demand: The case study of a school building in Eskisehir, Turkey. Sustain. Cities Soc. 2019, 47, 101483. [CrossRef] 22. Andersen, M.; Gochenour, S.J.; Lockley, S.W. Modelling non-visual effects of daylighting in a residential environment. Build. Envi- ron. 2017.[CrossRef] 23. Xue, P.; Mak, C.M.; Cheung, H.D. The effects of daylighting and human behavior n luminous comfort in residential buildings: A questionnaire survey. Build. Environ. 2014, 81, 51–59. [CrossRef] Sustainability 2021, 13, 3106 23 of 24

24. Acosta, I.; Campano, M.A.; Molina, J.F. Window design in architecture: Analysis of energy savings for lighting and visual comfort in residential spaces. Appl. Energy 2016, 168, 493–506. [CrossRef] 25. Konis, K.A. Novel circadian daylight metric for Building design and evaluation. Build. Environ. 2017, 113, 23–38. [CrossRef] 26. Fang, Y.; Cho, S. Design optimization of building geometry and fenestration for daylighting and energy performance. Sol. Energy 2019, 191, 7–18. [CrossRef] 27. Amoruso, F.M.; Udo, D.; Schuetze, T. Development of a building information modeling-parametric workflow based renovation strategy for an exemplary apartment building in Seoul, Korea. Sustainability 2018, 10, 4494. [CrossRef] 28. Hvass, T.; Jørgensen, H.; Volden, V. Bays, Balconies. Danish Architecture and Design Review. 2017. Available online: http: //danishdesignreview.com/architecture/tag/balconies (accessed on 25 January 2021). 29. Arnesen, H.; Kolas, T.; Matusiak, B. A guide to daylighting and shading systems at high latitude. Proj. Daylight 2015.[CrossRef] 30. Brembilla, E.; Chi, D.A.; Hopfe, C.J.; Mardaljevic, J. Evaluation of climate-based daylighting techniques for complex fenestration and shading systems. Energy Build. 2019, 203, 109454. [CrossRef] 31. Seyedolhosseini, A.; Masoumi, N.; Modarressi, M.; Karimian, N. Daylight adaptive smart indoor lighting control method using artificial neural networks. J. Build. Eng. 2020, 29, 101141. [CrossRef] 32. Alwetaishi, M.; Taki, A. Investigation into energy performance of a school building in a hot climate: Optimum of window-to-wall ratio. Indoor Built Environ. 2020, 29, 24–39. [CrossRef] 33. Shi, X.; Abel, T.; Wang, L. Influence of two motion types on solar transmittance and daylight performance of dynamic façades. Sol. Energy 2020, 201, 561–580. [CrossRef] 34. Fabbri, K.; Gaspari, J.; Bartoletti, S.; Antonini, E. Effect of facade reflectance on outdoor microclimate: An Italian case study. Sustain. Cities Soc. 2020, 54, 101984. [CrossRef] 35. Prikulis, J. Private Outdoor Spaces–Balconies and Loggias in Latvia. 2019. Available online: https://nda.rtu.lv/en/view/23507 (accessed on 25 January 2021). 36. Bielek, B.; Szabó, D.; Cehel’ovˇ á, D. Development and Experimental Verification of Sliding Elements of Transparent Loggia Enclosures in High-Rise Building. In Applied Mechanics and Materials; Trans Tech Publications Ltd.: Brno, Czech Republic, 2017; Volume 861, pp. 3–10. [CrossRef] 37. Horn, V. Balcony structures. Pollack Periodica 2011, 6, 115–130. [CrossRef] 38. Dunichkin, I. Aspects of designing construction of balcony parapets with photoelectric cells. In MATEC Web of Conferences; EDP Sciences: Les Ulis, France, 2016; Volume 86, p. 02014. [CrossRef] 39. Kisnarini, R.; Krisdianto, J.; Indrawan, I.A. Contribution of Balcony on Thermal Comfort: Rusunawa Surabaya. Open House Int. 2018, 43, 14–21. [CrossRef] 40. Nowak-Dzieszko, K.; Rojewska-Warchał, M. Influence of the balcony glazing construction on thermal comfort of apartments in retrofitted large panel buildings. Procedia Eng. 2015, 108, 481–487. [CrossRef] 41. Grudzi´nska,M. Glazed balconies as passive greenhouse systems–Potential of their use in Poland. Build. Serv. Eng. Res. Technol. 2016, 37, 555–572. [CrossRef] 42. Mésároš, P.; Spišáková, M.; Mandiˇcák, T.; Cabala,ˇ J.; Oravec, M.M. Adaptive Design of Formworks for Building Renovation Considering the Sustainability of Construction in BIM Environment—Case Study. Sustainability 2021, 13, 799. [CrossRef] 43. Wróbel, K.; Kubiszyn, W. Balconies, loggias and different thin-walled units in large panel buildings. In Cost C16, Improving the Quality of Existing Urban Building Envelopes: Structures; IOS Press Ebooks: Amsterdam, The Netherlands, 2007; pp. 179–186. 44. Schulzová, K.; Bošová, D.; Cernˇ á, A.M. The Impact of Extending the Loggia of a Precast Panel Building on Daylight and Insolation of the Apartments. In Proceedings of the 2018 VII. Lighting Conference of the Visegrad Countries (Lumen V4), Trebic, Czech Republic, 18–20 September 2018; pp. 1–4. [CrossRef] 45. Kalousek, L.; Brzoˇn,R.; Fišarová, Z. Analysis of thermal bridges in loggias of pre-cast concrete apartment buildings. MATEC Web Conf. 2019, 279, 03008. [CrossRef] 46. Katunský, D.; Nemec, M.; Kamenský, M. Airtightness of buildings in Slovakia. In Advanced Materials Research; Trans Tech Publications Ltd.: Bäch, Switzerland, 2013; Volume 649, pp. 3–6. [CrossRef] 47. Maachi, I.N.; Mokhtari, A.; Slimani, M.E.A. The natural lighting for energy saving and visual comfort in collective housing: A case study in the Algerian building context. J. Build. Eng. 2019, 24, 100760. [CrossRef] 48. Nocera, F.; Lo Faro, A.; Costanzo, V.; Raciti, C. Daylight performance of classrooms in a mediterranean school heritage building. Sustainability 2018, 10, 3705. [CrossRef] 49. Costanzo, V.; Evola, G.; Marletta, L.; Pistone Nascone, F. Application of Climate Based Daylight Modelling to the Refurbishment of a School Building in Sicily. Sustainability 2018, 10, 2653. [CrossRef] 50. Tsangrassoulis, A.; Santamouris, M.; Asimakopoulos, D.; Tregenza, P.R. A method for the estimation of illuminances on surfaces of urban canyons with balconies in sunlit areas. Int. J. Light. Res. Technol. 1999, 31, 5–12. [CrossRef] 51. Mardaljevic, J.; Andersen, M.; Roy, N.; Christoffersen, J. Daylighting metrics for residential buildings. In Proceedings of the CIE 27th Session, Sun City, South Africa, 9–16 July 2011. 52. Dogan, T.; Park, Y.C. A critical review of daylighting metrics for residential architecture and a new metric for cold and temperate climates. Light. Res. Technol. 2019, 51, 206–230. [CrossRef] 53. STN 730580. Daylighting in Buildings, Part–1 Basic Requirements, 1986 Part–2; Daylighting of Residential Buildings; Slovak Republic Office of Standards, Metrology and Testing: Bratislava, Slovakia, 2000. Sustainability 2021, 13, 3106 24 of 24

54. EN 12464-1:2012. Light and Lighting; Lighting of Work Places-Part 1: Indoor Work Places; Slovak Republic Office of Standards, Metrology and Testing: Bratislava, Slovakia, 2012. 55. American Society of Heating, Ventilating, and Air Conditioning Engineers (ASHRAE). Guideline 14-2002. In Measurement of Energy and Demand Savings; Technical report; American Society of Heating, Ventilating, and Air Conditioning Engineers: Atlanta, GA, USA, 2002. 56. CIE 231: 2019. CIE Classification System of Illuminance and Luminance Meters. Available online: http://cie.co.at/publications/ cie-classification-system-illuminance-and-luminance-meters (accessed on 25 January 2021). 57. Fryc, I.; Tabaka, P. The influence of different photometric observers on luxmeter accuracy for LEDs and FLs lamps measurements. Opt. Appl. 2019, 49, 345–354. [CrossRef] 58. Fryc, I. Spectral correction of a detector used in illuminance measurements. In Proceedings of the 11th Slovak-Czech-Polish Optical Conference on Wave and Quantum Aspects of Contemporary Optics, Stara Lesna, Slovakia, 21–25 September 1998; Volume 3820, pp. 343–348. [CrossRef] 59. Ferrero, A.; Velázquez, J.L.; Pons, A.; Campos, J. Index for the evaluation of the general photometric performance of photometers. Opt. Express 2018, 26, 18633–18643. [CrossRef] 60. Young, R.; Senft, M.; Tribes, D.; Peters, F. The relationship between measurement error and photometer cosine response performance index. Light. Res. Technol. 2016, 48, 26–34. [CrossRef] 61. Rosas, E.; Estrada-Hernández, A. Effect of photometric detector spectral response quality on white LED spectral mismatch correction factors. Appl. Opt. 2016, 55, 5267–5272. [CrossRef] 62. CSNˇ EN 12464-1. Svˇetloa osvˇetlení—Osvˇetlení pracovních prostor ˚u—Cˇ ást 1: Vnitˇrní pracovní prostory. 2004. Available online: http://www.technicke-normy-csn.cz/360450-csn-en-12464-1_4_69656.html (accessed on 25 January 2021). 63. Dehoff, P. Quality criteria as part of the european standardization-the revision of en 12464-1 “Lighting of interior workplaces”. Light Eng. 2010, 18, 30–31. 64. Standard CSNˇ 360014. Measurements of Daylighting; Czechoslovak Republic, Office of Standards, Metrology and Testing: Prague, Czechoslovak Republic, 1978. 65. Darula, S. Príspevok k meraniu vonkajšej zrovnávacej osvetlenosti podl’a CSNˇ 36 0011-2 (Contribution to the exterior reference illuminance measurement according to the CSNˇ 36 0011-2). In Proceedings of the Kurz osvˇetlovací techniky XXIII, Dlouhé Stráne, Czechia, 4–6 October 2004; pp. 15–18. 66. Dolnikova, E.; Katunsky, D.; Darula, S. Assessment of overcast sky daylight conditions in the premises of engineering operations considering two types of skylights. Build. Environ. 2020, 180, 106976. [CrossRef]