MAKING A RETURN ON INVESTMENT IN PASSIVE ARCHITECTURE TERRACED HOUSES DEVELOPMENT Wan Rahmah Mohd Zaki Universiti Teknologi Malaysia(UiTM) Malaysia E-mail: [email protected] Abdul Hadi Nawawi Universiti Teknologi MalaysiaQJiTM) Malaysia E-mail: [email protected] Sabarinah Sh Ahmad Universiti Teknologi MalaysiaQJiTM) Malaysia E-mail: [email protected] ABSTRACT The main feature of a conventional terraced housing development is rows of rectangular shaped houses with the narrow facade as the frontage. Consequently, this limits natural cross ventilation and daylight penetration into the middle of the houses; and cause for unnecessary energy consumption on mechanical cooling and artijicial lighting to make the living spaces comfortable for occupants. Such inconsideration is mainly attributed to the optimum configuration of houses which offers the most economic return desired by the developer. Passive Architecture (PA) design strategies can make terraced houses more conducive for occupants as well as gives reasonable returns to the developer. The idea is demonstrated on a hypothetical double storeys terraced scheme in a 2.5 acre site whereby it is transformed intofour types of PA terraced houses development. The Return on Invesfment of the PA terraced houses is ascertained for two situations, ie., (i) fwed sales price for all types of house; and (ii) added premium to PA terraced houses due to the positive unintended effects such as low density housing, etc. If critical criteria for demand and supply in housing remain constant, it is found that PA terraced housing development offers competitive returns to the developer relative to the returns for conventional terraced housing scheme. Keyworh: Orientation, Indoor Comfort and Operational Energy 1.0 INTRODUCTION 1.1 Housing and Energy The recent public awareness on sustainability calls for housing to not only serves as a basic shelter but also to be energy efficient, i.e., designed to make occupants need low operational energy. Such requirement is an important design consideration because the cost of energy has been increasing and will continue to increase throughout the building's life time. In so far built environment is concerned, operational energy requirement for a house can be low if the house is designed to make occupants feel thermally and visually comfortable, naturally. 1.2 Objective of Paper This paper propagates a change in the conventional terraced houses design to emulate Passive Architecture (PA) design strategies so that the houses can be naturally comfortable for occupants that they rely less on commercially supplied energy. Based on that notion, this paper intends to demonstrate that PA terraced housing scheme is capable of offering competitive Return on Investment 01) to the developer when compared to conventional terrace housing that rarely addresses energy issue. 2.0 COMFORTABLE INDOOR CONDITIONS 2.1 Thermal Comfort There are two components of variables that influence thermal comfort. Firstly, the microclimate, namely: air temperature, radiant temperature, humidity and air speed. These are fixed variables and should be considered in the building design. The second component is highly subjective as it relates to occupant's personal (activity level, clothing), biological (age, gender), environmental (opedclose window) adaptability as well as expectation on thermal comfort (Aulicierns and Szokolay, 1997). Whilst thermal comfort can be generalized by the first set of fixed variables, people's perception of comfort is unique. Nonetheless, there have been many studies on thermal comfort values for people in the hot and humid tropics. Sh. Ahmad (2004) in her study of thermal comfort and energy performance of urban multi storey residential buildings in Malaysia reaffirmed the local thermal comfort is within 2.5K from 26.1°C. La Roche (2001) advised the largest single source of thermal gain for building in the tropical climate is by solar radiation. Hence, it is wise to aim to reduce heat gain from the sun by minimizing the amount of solar radiation that falls on to the building envelope. 2.2 Vical Comfort Meanwhile, natural visual comfort occurs when occupant feels comfortable doing specific task without the need of artificial lighting, but only using daylight. However, the quality of daylight entering a space depends on both internal and external factors, simultaneously. Whilst external factors relate to the sky and the ground covers; the internal factors are within the scope of built environment. For instance, the size, type and position of the openings; the depth and shape of the rooms; and the colours of the internal surfaces are main internal factors which affect daylight in a room (Majoros, 1998). 3.0 PASSIVE ARCHITECTURE Passive Architecture (PA) describes a building that is designed with climate factors in mind to provide comfortable indoor conditions, naturally. The aim is to make building occupant need less of operational energy. In hot and humid tropics like Malaysia, PA design strategies mainly aim to avoid heat from the sun, promote breeze f~omthe prevailing wind and ensure daylight into the building (Hyde, 2000). The above-described idea is not new. Local Malay traditional houses have large overhangs on the east and west sides to alleviate heat gain. There are also air outlets at ceiling level to allow lnternotiono~.~?n~posiumbl 5cvclopin.g Economies: Ci~tllrnorrillitics~?n~c~~~{)Di~srrities ~~... hot air to escape. Coupled with raised floor and double volume roof, such traditional houses provide indoor comfortable conditions, naturally (Figure 1). Figure 1: 'Climate Design of a Malay House' by Ghazali, M. (2007) Abroad, others had documented the same 'thought since 1960s. Then, it was believed that a building designed with climate in mind, instead of against it would make occupants healthy (Olgyay, 1960). Subsequently, this approach was experimented and realised by other researchers such as Hyde (2000) as being a commonsensical act towards sustainability due to its direct relationship with energy conservation. 3.2 Terminology Various terminologies were used to describe buildings that are designed with climate and it is notably expressed as 'passive' to portray a 'defensive' or 'protective' attitude against climate (Table 1). Regardless the terminologies, their aims remain the same - to promote building independence from commercially supplied energy. In this paper, the term PA is applied to reflect the endeavour as being a basic responsibility of architects. Table 1: Terrainologies for Climatically Designed Buildings Terminology 1 ~uthor,year Bioclmatic Design Olgyay, 1963 CIimatic Responsive Design Hyde, 2000 Climate Sensitive Design Emmanuel, 2005 Green Building Buchanan, 2005 Passive Solar Design ~ain-bedet al., 2002 Passive House Rohracher, 2005 Passive System Design Szokolay, 2006 564IPage 4.0 TERRACED HOUSES 4.1 Local Residential Market A report by National Property Information Centre (NAPIC) in 2008 stated that the bullc of housing developments offered in the local residential market are 2 to 3 storeys terraced houses. In the third quarter of 2008, from the total 4,158,232 units of housing completed, 876,948 units were terraced houses, i.e. about 21% of the local residential properties market. A physical survey at the Malaysia Property Exhibition (MAPEX) 2008 supports this fact whereby fiom 85 residential developments offered at that time, terraced houses formed the largest type of property on offered (Figure 2) (Mohd Zaki, et al., 2008). SmsTitie Residences Sem-Detached Houses Figure 2: Four Types of 85 ResidentiaI Developments Offered at MAPEX 2008 As such, making terraced houses to be less dependent on commercially supplied energy will have a significant impact in lowering the domestic energy demand at national level. 4.2 Typical Terraced House Floor Layout A typical two storeys terraced house has a frontage measuring 18 to 22 feet (ft)' wide with depth varies from 40 to 70 feet. A close look at these typical terraced houses and the housing layouts reveal that there are two design issues that would result for uncomfortable indoor conditions and the subsequent use of operational energy to make the spaces falls into the acceptable comfort range. 4.2.1 Deep Floor Plan Firstly, a typical two storeys terraced house has deep floor plan which centre has no access to external opening. Typically, this space is assigned to be the dining area on the ground floor; whereas on the first floor it is usually the family area. As such, regardless the orientation of the house, these two areas will not get much daylight and may result for the use of artificial lighting. As a result, these spaces need mechanical cooling because the deep floor plan deprives the areas from natural cross ventilation (Figure 3). GROUND FLOOR v! 1 Lack of claylight and mtud uoss ventiMi011 South FIRST FLOOR Figure 3: Typical Terraced House Floor Layout 4.2.2 Orientation Secondly, the site layout of a conventional terraced housing scheme is pegged against commercial return whereby maximum no. of housing units gives the highest Return on Investment (ROI). Since ROI takes precedence in a housing development and in the quest to fit in the maximum number of houses, several units receive tremendous heat gain into the indoor spaces due to poor site orientation. With reference to Figure 3, the fiont of a typical double storeys terraced house is normally assigned as the living area on the ground floor and master bedroom on the first floor. For a house with west frontage, the living area and the bedroom are exposed to heat gain in afternoon; and at night, the heat absorbed by the bricked facade is released into these spaces. As a result, occupants become thermally uncomfortable in the afternoon and at night. Consequently, they would make adjustment that involves mechanical cooling and the use of commercially supplied energy. International Sytrrposirzz Itt Devr?lo(;DtgEcorromies: Cornrrrontriities Aozong 5iversiticr.s 5.0 RETURN ON INVESTMENT (R01) ROI is a common tool used to ascertain the economic viability of almost any investment from the investor's viewpoint. Literally, it determines whether a proposed investment is wise; and how well it will repay the investor (Investopedia, 2008).