Article Developing a Landscape Sustainability Assessment Model Using an Analytic Hierarchy Process in Korea
Hyung-Sook Lee 1 and Eun-Yeong Park 2,*
1 Department of Landscape Architecture, Kyungpook National University, Daegu 41561, Korea; [email protected] 2 Department of Environmental Landscape Architecture, Joongbu University, Geumsan 32713, Korea * Correspondence: [email protected]; Tel.: +82-41-750-6294
Received: 27 October 2019; Accepted: 27 December 2019; Published: 30 December 2019
Abstract: With the increasing interest in integrative sustainable development, there has been a strong need for a landscape sustainability assessment tool independent from the existing green building rating system. This study aimed to establish an assessment model to objectively evaluate landscape sustainability using an analytic hierarchy process (AHP). Through an extensive literature review and expert survey, an initial list of assessment items was derived and used to set up an AHP model. An AHP survey with landscape architects and architects/engineers was then conducted to determine the importance of the assessment factors. In addition, the model was applied to three projects that were previously certified by a green building rating system in Korea. The AHP results showed that “site context” ranked as the most important factor of landscape sustainability followed by “soil and vegetation,” “maintenance,” “water,” “health and wellbeing,” and “materials.” Among the 20 assessment factors, “monitoring plan” was evaluated as the most important index, followed by “protection of cultural heritage” and “long-term management plan.” Landscape architects evaluated “soil and vegetation” as the most important in the assessment, while the engineers/architects group rated “site context” as the most important. When tested by applying them to the previously certified projects, the developed factors provided more objective and detailed information on landscape sustainability.
Keywords: landscape sustainability; assessment model; landscape performance; analytic hierarchy process; sustainability rating system
1. Introduction Active discussions are being held worldwide on ways of improving the environment, such as optimizing buildings’ energy use and reducing CO2 emissions to tackle climate change [1–3]. With the increasing awareness of severe environmental problems, such as contamination of the natural environment, destruction of the ecosystem, resource depletion, water shortages, and extreme weather events, there has been a strong need for sustainable development and an environmental paradigm throughout society [4,5]. As an outcome of these discussions, assessment criteria on the environmental performance of buildings have been established and implemented. Led by the Building Research Establishment Environment Assessment Method (BREEAM) of the UK in 1991 [6], there has been the development of Canada’s SBTool [7], Japan’s Comprehensive Assessment System for Built Environment Efficiency (CASBEE) [8], Australia’s Green Star [9], Singapore’s Green Mark [10], and the US’s Leadership in Energy and environmental Design (LEED) V1.0 enacted by the U.S. Green Building Council (USGBC) in 1998 [11–13]. Korea implemented the “Green Building Certification System” in 2002 [14].
Sustainability 2020, 12, 301; doi:10.3390/su12010301 www.mdpi.com/journal/sustainability Sustainability 2020, 12, 301 2 of 15
The initial sustainability assessment systems focused on individual buildings, but with the increasing awareness of the importance of environmental issues occurring at the city/neighborhood levels, sustainability assessment systems worldwide have established separate landscape assessment systems at the city/neighborhood levels in addition to those for individual buildings. The US, in particular, has been implementing the Sustainable Sites Initiative (SITES) since 2012, apart from its existing green building certification system LEED, through which various landscape sustainability factors of all project sites are assessed regardless of buildings. This has also led to sustainable and integrated design, from development planning of the project site to design and management [11]. However, while the ecology category of the Green Standard for Energy and Environmental Design (G-SEED), Korea’s green building rating system, includes sustainability assessment items related to landscape and external environment, this is strictly limited. G-SEED can only assess projects that include buildings and, thus, it is inadequate for assessing various forms of landscapes or parks, green spaces, and other facilities [15]. Precedent studies on landscape assessment systems have comparatively analyzed the BREEAM, LEED, and CASBEE [15–18], and some have examined the similarities and differences by comparing the BREEAM and LEED with Korea’s green building rating system [19,20]. Studies on green space have either comparatively analyzed the sustainability of apartment complexes [21], Seoul’s new built-up areas and green spaces in new town housing complexes of metropolitan areas [22], using the assessment items of “land use and transportation” and “ecological environment” in Korea’s Green Building Certification System, or established village-type sustainability factors [23]. These studies have performed landscape assessment using the limited green space assessment items of the certification system that targets buildings. The studies related to sustainability assessment factors have used various methods, such as literature reviews [4,13], the Delphi method [24,25], expert surveys [26,27], and field surveys [3,28,29]. Recently in Korea, there has been a need for an independent system of landscape sustainability assessment, and active discussions have been made accordingly. However, there is a gap in the perception of sustainability assessments for outdoor spaces and landscapes as well as directions for improvement between non-landscape experts, such as architects/engineers, and landscape experts [11,30]. The purpose of the research is to analyze the possibility of using an analytic hierarchy process (AHP) as a decision-making tool in the process of selecting the assessment items for a landscape sustainability rating system. This study established the following three objectives:
(1) to establish an assessment model to objectively evaluate landscape sustainability; (2) to comparatively analyze the importance of assessment factors by landscape architects and non-landscape architects; (3) to test the applicability of the model developed in this study by applying it to G-SEED-certified projects.
2. Methodology
2.1. Research Scope and Sampling The assessment items in this study were limited to assessment criteria that may be used to establish or remodel outdoor spaces of buildings, parks, and green areas in urban or suburban areas. Assessment criteria for sustainable buildings or community environment were excluded. In the current situation, where only building certification exists in Korea, we focused on developing assessment criteria that may be used as basic data to establish sustainability certification for landscaping and outdoor spaces in the future. Interviews and surveys were employed to collect data in this study. The sample for the AHP survey included 70 landscape architecture experts as well as 71 engineers/architects who had experience in the G-SEED certification process. Given the discrepancy between the landscape architect group Sustainability 2020, 12, 301 3 of 15 and the architects/engineers group in terms of perception on landscape sustainability rating systems, Sustainability 2020, 12, x FOR PEER REVIEW 3 of 14 purposive sampling techniques were employed to select the respondents from the two groups. 2.2. Analytic Hierarchy Process (AHP) 2.2. Analytic Hierarchy Process (AHP) The analytic hierarchy process (AHP) is one of the most widely used methods in multi-attribute The analytic hierarchy process (AHP) is one of the most widely used methods in multi-attribute decision making. The AHP, developed by Thomas Saaty in 1977, was designed to help decision decision making. The AHP, developed by Thomas Saaty in 1977, was designed to help decision makers makers incorporate qualitative and quantitative aspects of a complex problem with multiple incorporate qualitative and quantitative aspects of a complex problem with multiple subjective criteria. subjective criteria. It is considered a promising framework for evaluation due to its potential to It is considered a promising framework for evaluation due to its potential to explicitly take into account explicitly take into account conflictual, incommensurable, and uncertain effects of decisions. The conflictual, incommensurable, and uncertain effects of decisions. The AHP involves the following basic AHP involves the following basic steps: (1) the building of a hierarchical AHP model consisting of steps: (1) the building of a hierarchical AHP model consisting of criteria and factors of the problem, criteria and factors of the problem, (2) pairwise comparisons between elements at each level to derive (2) pairwise comparisons between elements at each level to derive the weights and relative priorities of the weights and relative priorities of factors, and (3) the synthesis of the priorities of the criteria for factors, and (3) the synthesis of the priorities of the criteria for weights into an overall rating based on weights into an overall rating based on which best alternative is decided. which best alternative is decided. The strength of the AHP method lies in its ability to reduce complex decisions to a series of one- The strength of the AHP method lies in its ability to reduce complex decisions to a series of on-one comparisons by assisting with identifying and weighting selection criteria, analyzing the data one-on-one comparisons by assisting with identifying and weighting selection criteria, analyzing the collected for the criteria, and expediting the decision-making process [31]. Comparisons can be made data collected for the criteria, and expediting the decision-making process [31]. Comparisons can according to preference, importance, or likelihood, whichever is most appropriate for the elements be made according to preference, importance, or likelihood, whichever is most appropriate for the considered. elements considered. The AHP has already been applied for developing sustainability assessment systems, such as The AHP has already been applied for developing sustainability assessment systems, such as sustainable community rating tools [23], Korean traditional house sustainability [32], and sustainable sustainable community rating tools [23], Korean traditional house sustainability [32], and sustainable interior material [33]. The AHP is implemented using Expert Choice software, which can provide interior material [33]. The AHP is implemented using Expert Choice software, which can provide visualized results. visualized results.
2.3. Research Framework In this study, study, we we prioritized prioritized the the factors factors for for assessing assessing landscape landscape sustainability sustainability and and developed developed an anassessment assessment model model using using the theAHP AHP method. method. The The process process of our of ourstudy study went went through through three three stages stages for forassessing assessing landscape landscape sustainability, sustainability, involving involving (1) de (1)fining defining the theassessment assessment criteria criteria and andfactors, factors, (2) (2)identifying identifying the theweights weights of ofcriteria criteria and and factor factorss through through the the AHP AHP method, method, and and (3) (3) applying the assessment model to G-SEED-certifiedG-SEED-certified projects.projects. The overalloverall researchresearch process process is is presented presented in Figurein Figure1, and 1, and the followingthe following subchapters subchapters describe describe each phaseeach phase in detail. in detail.
Figure 1. Research flowchart.flowchart.
2.3.1. Phase I: Defining the Criteria and Factors An extensive review of precedent research and previous evaluation instruments related to landscape sustainability was performed in order to determine the initial set of assessment factors. A variety of factors concerning outdoor or landscape sustainability were derived from the existing rating systems, including LEED, Leadership in Energy and Environmental Design for New Sustainability 2020, 12, 301 4 of 15
2.3.1. Phase I: Defining the Criteria and Factors An extensive review of precedent research and previous evaluation instruments related to landscapeSustainability 2020 sustainability, 12, x FOR PEER was REVIEW performed in order to determine the initial set of assessment factors.5 of 14 A variety of factors concerning outdoor or landscape sustainability were derived from the existing rating ・Provide outdoor systems, including LEED, Leadership in Energy and Environmental Design for New Construction spaces for social (LEED-NC), Leadership in Energy and Environmentalinteraction Design for Neighborhood Development (LEED-ND), SITES,・Rationality Seattle of site Green Factor, and Helsinki・Monitor Green Factor [14,34–39] (Table1). We conductedmanagement unstructured plans interviews withperformance five experts of in landscape architecture in order to Maintenance elaborate the initialconsidering criteria the and factors from the literaturesustainable review. design The experts checked if the initial sets environment practices of factors were mutually exclusive and non-redundant. Based on their comments, a total of 6 criteria and 34 factors were generated. Since assessment factors should be defined based on expert knowledge and the local context of Since assessment factors should be defined based on expert knowledge and the local context of Korea, we conducted the unstructured interviews with 11 practitioners from landscape architecture Korea, we conducted the unstructured interviews with 11 practitioners from landscape architecture firms. The interviewees were asked to identify which factors they considered most important for the firms. The interviewees were asked to identify which factors they considered most important for the assessment of landscape sustainability to develop a new assessment system on a 5-point Likert scale. assessment of landscape sustainability to develop a new assessment system on a 5-point Likert scale. The interviewees had 10–25 years’ experience as practitioners in the field of landscape planning and The interviewees had 10–25 years’ experience as practitioners in the field of landscape planning and design. As a result of the interviews, 20 items in six criteria were selected. design. As a result of the interviews, 20 items in six criteria were selected.
2.3.2. Phase II: Identifying the Weights of Criteria and Factors throughthrough thethe AHPAHP MethodMethod An AHP model was formatted based on the literat literatureure review and expert interviews (Figure (Figure 22).). In addition,addition, an an AHP AHP questionnaire questionnaire was was designed designed with with a pairwise a pairwise comparison comparison format format to give to the give relative the importancerelative importance among theamong criteria the criteria and factors. and factors. The values The values of importance of importance were based were based on a 9-point on a 9-point scale, withscale, a with value a ofvalue 9 indicating of 9 indicating the absolute the absolute importance importance of one item of one over item the otherover andthe other a value and of 1a meaningvalue of equal1 meaning importance. equal importance. Table2 shows Table the 2 AHP shows pairwise the AHP comparison pairwise comparison scale. scale.
Figure 2. Analytic hierarchy process model.
Table 2. AHP pairwise comparison scale (source: Saaty 1977).
Intensity of Relative Importance Definition 1 Equal importance 3 Weak importance 5 Essential or strong importance 7 Demonstrated importance 9 Absolute importance 2,4,6, and 8 Intermediate values between two adjacent judgments
A total of 183 copies of the questionnaire were distributed to experts from different fields, such as landscape architecture, architecture, and engineering, via e-mail in October of 2018. The respondents ranged in age between 20 s and 60 s and had 3–43 years’ experience in practice. While the response rate was 100%, only 141 responses whose consistency ratio (CR) was less than 0.19 were Sustainability 2020, 12, 301 5 of 15
Table 1. Derivation of landscape sustainability assessment factors.
Items of Existing Rating Systems and Assessment Subject Criteria G-SEED LEED-NC/ND SITES Seattle Green Factor Helsinki Green Factor Building Neighborhood Development Landscape Greenery Greenery Ecological value of Select brownfields or grayfields • • existing site for redevelopment Outside pedestrian • Preserve threatened or endangered Landscaped areas • Brownfield redevelopment • • Site context walkway network species and their habitats Bio-retention facilities Smart location • Proximity of • Use integrated site • • public transportation development process Minimize soil disturbance in design • Plantings and construction • Preserved vegetation Biotope creation Protect or restore habitat Green roofs • • • Use native plants • and soil Green network Historic resource • Vegetated walls Soil/vegetation • • Preserve or restore appropriate • Planted/new vegetation Green space ratio preservation and • Structural soil systems • • plant biomass on site • Green roofs Ecological area ratio adaptive use Drought tolerance of • • Preserve plant communities native • Green walls, vertical areas • native plant species • to ecoregion Permeable pavement • Preserve wetlands Rain garden • Approved • Validity of rainwater load Protect or restore habitat Protect and restore riparian areas, • Stormwater • • • water features • reduction measures Site design for habitat or wetlands, and shoreline buffers Wetland Water • Use of • Rainwater utilization wetland and water Rehabilitate lost streams, wetlands, • Infiltration pit • • harvested rainwater • Install graywater body conservation and shorelines Retention swale covered • Permeable paving • Manage stormwater on site • with natural vegetation • Selection of native species • Use of certified green • products for effective Tree species native to Use recycled content materials • recycling (prerequisite) • Helsinki and flowering trees Materials Use regional materials Information display for • and shrubs • carbon emissions of materials Protect and maintain unique Community facility • • Maximize open space cultural and historical places Whether to create pedestrian • Adjacent public right • Historic resource Provide opportunities for outdoor • walkway inside complex • • of way or public Health/wellbeing preservation and physical activity Whether to install bike storage open spaces • adaptive use Provide outdoor spaces for and bike road • social interaction Rationality of site • Monitor performance of sustainable management plans • Maintenance design practices considering the environment Sustainability 2020, 12, 301 6 of 15
Table 2. AHP pairwise comparison scale (source: Saaty 1977).
Intensity of Relative Importance Definition 1 Equal importance 3 Weak importance 5 Essential or strong importance 7 Demonstrated importance 9 Absolute importance 2,4,6, and 8 Intermediate values between two adjacent judgments
A total of 183 copies of the questionnaire were distributed to experts from different fields, such as landscape architecture, architecture, and engineering, via e-mail in October of 2018. The respondents ranged in age between 20 s and 60 s and had 3–43 years’ experience in practice. While the response rate was 100%, only 141 responses whose consistency ratio (CR) was less than 0.19 were used for further analysis. The CR value reflects the internal consistency and values of CR 0.2 were also accepted [40]. ≤ The respondents were composed of landscape architects (49.6%) and engineers/architects (50.4%) (Table3).
Table 3. Demographic data of respondents.
Landscape Engineers/Architects Total (n = 141) Architects (n = 70) (n = 71) Male 47(33.3%) 63(44.7%) 110(78%) Gender Female 23(16.3%) 8(5.7%) 31(22%) 20 s 20(14.2%) 8(5.7%) 28(19.8%) Age 30 s 36(25.5%) 26(18.4%) 62(44.0%) 40–60 s 14(10%) 37(26.2%) 51(36.2%) Practitioner experience (average years) 7.67 13.2 10.45
Expert Choice, decision-making software developed to implement the AHP, was used to produce weights, consistency ratios, and rankings. All the comparisons were synthesized to rank the assessment items. The output of the AHP was a prioritized ranking of the assessment items based on the overall importance expressed by the participants.
2.3.3. Phase III: Applying the Developed Assessment System We tested the applicability of the developed assessment system by assessing three projects that were previously certified by G-SEED, a sustainable building rating system in Korea. The three G-SEED-certified projects—an office campus landscape, hotel and commercial building landscape, and housing complex landscape—had different characteristics in terms of site area, landscape area, design intentions, etc. (Table4). For the assessment, each item was rated on a 5-point Likert scale for sustainability by nine experts who had participated in the projects, and the means as well as previously derived weightings were considered in calculating the percentages of each field and project. SustainabilitySustainabilitySustainability 2020 2020, 12 2020, 12, x, FOR,x 12 FOR, xPEER FOR PEER REVIEWPEER REVIEW REVIEW 6 of6 of 14 146 of 14
usedused usedfor for further furtherfor further analysis. analysis. analysis. The The CR The CR value CRvalue value reflects reflects reflects the the internal theinternal internal consistency consistency consistency and and valuesand values values of of CR CR of ≤ CR≤0.2 0.2 ≤were were0.2 were alsoalso also acceptedaccepted accepted [40].[40]. [40]. TheThe The respondentsrespondents respondents werewere were composedcomposed composed ofof landscapeoflandscape landscape architectsarchitects architects (49.6%)(49.6%) (49.6%) andand and engineers/architectsengineers/architectsengineers/architects (50.4%) (50.4%) (50.4%) (Table (Table (Table 3). 3). 3).
TableTableTable 3. 3. Demographic Demographic 3. Demographic data data of data of respondents. respondents. of respondents.
LandscapeLandscapeLandscape Architects Architects Architects EngineersEngineersEngineers/Architects/Architects/Architects TotalTotalTotal
(n( n= =70)( 70)n = 70) (n( n= =71)( 71)n = 71) (n( n= =141)( 141)n = 141) MaleMale Male 47(33.3%)47(33.3%)47(33.3%) 63(44.7%) 63(44.7%) 63(44.7%) 110(78%)110(78%)110(78%) GenderGenderGender FemaleFemaleFemale 23(16.3%)23(16.3%)23(16.3%) 8(5.7%) 8(5.7%) 8(5.7%) 31(22%)31(22%)31(22%) 2020 s s20 s 20(14.2%) 20(14.2%) 20(14.2%) 8(5.7%) 8(5.7%) 8(5.7%) 28(19.8%) 28(19.8%) 28(19.8%) AgeAge Age 3030 s s30 s 36(25.5%) 36(25.5%) 36(25.5%) 26(18.4%) 26(18.4%) 26(18.4%) 62(44.0%) 62(44.0%) 62(44.0%) 40–6040–6040–60 s s s 14(10%) 14(10%) 14(10%) 37(26.2%) 37(26.2%) 37(26.2%) 51(36.2%) 51(36.2%) 51(36.2%) PractitionerPractitionerPractitioner experience experience experience 7.677.67 7.67 13.213.2 13.2 10.4510.4510.45 (average(average(average years) years) years)
ExpertExpertExpert Choice, Choice, Choice, decision-making decision-making decision-making software software software devel devel developedoped opedto to implement implementto implement the the AHP, theAHP, AHP, was was wasused used usedto to to produceproduceproduce weights, weights, weights, consistency consistency consistency ratios ratios ratios, and, and ,rankings. and rankings. rankings. All All the Allthe comparison thecomparison comparisons swere weres weresynthesized synthesized synthesized to to rank rank to rankthe the the assessmentassessmentassessment items. items. items. The The output The output output of of the the of AHP theAHP AHPwas was a was aprio prio aritized prioritizedritized ranking ranking ranking of of the the of assessment theassessment assessment items items items based based based on on on thethe overall theoverall overall importance importance importance expressed expressed expressed by by the theby participants. theparticipants. participants.
2.3.3.2.3.3.2.3.3. Phase Phase Phase III: III: Applying ApplyingIII: Applying the the Developed theDeveloped Developed Assessment Assessment Assessment System System System WeWe tested Wetested tested the the applicability theapplicability applicability of of th th eof edeveloped thdevelopede developed assessment assessment assessment system system system by by assessing assessingby assessing three three three projects projects projects that that that werewere werepreviously previously previously certified certified certified by by G-SEED, G-SEED,by G-SEED, a asustainabl sustainabl a sustainable ebuilding buildinge building rating rating rating system system system in in Korea. Korea. in Korea. The The threeThe three three G- G- G- SEED-certifiedSEED-certifiedSEED-certified projects—an projects—an projects—an office office office campus campus campus landscape, landscape, landscape, hotel hotel hoteland and commercial and commercial commercial building building building landscape, landscape, landscape, and and and housinghousinghousing complex complex complex landscape—had landscape—had landscape—had different different different characterist characterist characteristicsics in in icsterms terms in terms of of site site of area, sitearea, area,landscape landscape landscape area, area, area,design design design Sustainability 2020, 12, 301 7 of 15 intentions,intentions,intentions, etc. etc. (Table etc.(Table (Table 4). 4). For For4). the Forthe assessment, theassessment, assessment, ea eachch eaitem itemch itemwas was ratedwas rated rated on on a aon5-point 5-point a 5-point Likert Likert Likert scale scale scalefor for for sustainabilitysustainabilitysustainability by by nine bynine nineexperts experts experts who who whohad had participathad participat participateded in ined the thein projects, theprojects, projects, and and theand the means themeans means as as well wellas wellas as as previouslypreviously derived derived weightings weightings were were considered considered in calculatingin calculating the thepercentages percentages of eachof each field field and and previously derivedTable weightings 4. Study siteswere usedconsidered to test developedin calculating assessment the percentages factors. of each field and project.project.project. LH-HQ Renaissance Sejong TableTableTable 4. 4. Study Study 4. Study sites sites used sites used toused to test test to developed testdeveloped developed assessment assessment assessment factors. factors. factors. Project type Company building Hotel and business district Housing complex LH-HQLH-HQ RenaissanceRenaissance SejongSejong Total area 97,165.70LH-HQ m2 Renaissance18,489.70 m 2 Sejong7,261,643 m2 ProjectProjectProject type type type CompanyCompanyCompany building building building HotelHotel andHotel and business businessand business district district district HousingHousingHousing complex complex complex 2 2 2 LocationTotalTotal areaTotal area area Jinju, Gyeongsangnam-do97,165.7097,165.7097,165.70 m m2 2 m Gangnam-gu,18,489.7018,489.7018,489.70 m m2 Seoul2 m 7,261,643 Dajeong-dong,7,261,6437,261,643 m m2 2 m Sejong LandscapeLocationLocation areaLocation Jinju,Jinju,30,690 Gyeongsangnam-doJinju, Gyeongsangnam-do m Gyeongsangnam-do2 (31.59%) Gangnam-gu,Gangnam-gu, 2954Gangnam-gu, m2 (15.98%) Seoul Seoul Seoul Dajeong-dong,Dajeong-dong,Dajeong-dong, 33,891 m Sejong2 Sejong(46.67%) Sejong 2 2 2 LandscapeLandscapeLandscape area area area 30,69030,690 30,690m m2 (31.59%)2 (31.59%) m (31.59%) 29542954 m2954 m2 (15.98%)2 (15.98%) m (15.98%) 33,89133,891 33,891m m2 (46.67%)2 (46.67%) m (46.67%) Wide open space WideWide openWide open space open space space Redevelopment project in urban Multiple layers of planting in RedevelopmentRedevelopmentRedevelopment project project project in in urban urban in urban Dry stream using LID technique MultipleMultipleMultiple layers layers layersof of planting planting of planting in in high high in high center DryDry stream streamDry stream using using LIDusing LID technique techniqueLID technique Landscape high density centercenter center Wind path, central open space LandscapeLandscapeLandscape densitydensity density Emphasis on historicity and WindWind path,Wind path, central path, central central open open space open space space EmphasisEmphasisEmphasis on on historicity historicity on historicity and and and characteristicscharacteristicscharacteristicscharacteristics Multi-purpose Multi-purposeMulti-purpose Multi-purpose playground, playground, playground, playground, plaza,plaza,plaza, plaza,courtyard, courtyard, courtyard,courtyard, complex complex complex complex symbolismsymbolismsymbolismsymbolism ecologicalecologicalecologicalecological pond pond pond withpond with with aquatic with aquatic aquatic aquatic plants, plants, plants, circulationcirculationcirculationcirculation community community community streets streets streets streets TerrestrialTerrestrialTerrestrialTerrestrial and and andaquatic aquaticand aquatic aquatic biotopes biotopes biotopes biotopes rooftopplants,rooftoprooftop gardenrooftop garden garden garden
Site planSiteSite plan planSite plan
SustainabilitySustainabilitySustainability 2020 2020, 12 2020, 12, x, FOR,x 12 FOR, xPEER FOR PEER REVIEWPEER REVIEW REVIEW 7 of7 of14 714 of 14
ViewView ofView ofoverall overall of overall View of overall site sitesite site
4 Stars4 Stars4 (Total Stars (Total (Total67.55 67.55 points) 67.55 points) points) 55 Stars5 Stars Stars5 (Total Stars (Total(Total (Total81.85 81.85 points) 81.85 points) points) points) 5 Stars55 Stars Stars5 (Total Stars (Total (Total (Total80.30 80.30 80.30 points) 80.30 points) points) points) 4 Stars (Total 67.55 points) - Green- Green- Greenspace space ratiospace ratio (0.5/2 ratio (0.5/2 points)(0.5/2 points) points) G-SEEDG-SEEDG-SEED rating rating rating-- Green Green- Green - Greenspace spacespace ratiospace ratio (1.5/2 ratio (1.5/2 (1.5 points)(1.5/2/ 2points) points) points) - Green- Green Green- Greenspace space space ratiospace ratio ratio (0.5/2 ratio (0.5/2 (0.5 points)(0.5/2 points)/2 points) points) - Green space ratio (0.5/2 points) - Ecological- Ecological- Ecological area area (3/6 area (3/6 points) (3/6points) points) G-SEED ratingandand landscape andlandscape and landscape -- Ecological Ecological- Ecological - Ecological area area (3/6 area (3/6 (3 points)/6 (3/6points) points) points) - Ecological- Ecological Ecological- Ecological area area area (3/6 area (3/6 (3points) (3/6/points)6 points) points) - Ecological area (3/6 points) - Biotope- Biotope- Biotope creation creation creation (4/4 (4/4 points) (4/4points) points) landscape itemitemitem scoresscoresitem scores scores -- Biotope Biotope- Biotope - Biotope creation creationcreation creation (4/4 (4/4 (4 points)/4 (4/4points) points) points) - Biotope- Biotope Biotope- Biotope creation creation creation creation (4/4 (4/4 points) (4 (4/4points)/4 points) points) - Biotope creation (4/4 points) - Ecological- Ecological- Ecological value value ofvalue ofsite site of(0/2 (0/2site (0/2 -- Ecological Ecological- Ecological- Ecological value value ofvalue ofsite of sitesite of(0/2 (0/2site points) (0/2points) points) - Ecological- Ecological Ecological - Ecological value value value ofvalue ofsite ofsite of(2/2 site (2/2site points) (2/2points) points) - Ecological value of site (0/2 points) (2/2 points) points)points)(0points) /2 points)
3.3. Results Results3. Results 3. Results 3.1.3.1. The3.1. The Relative The Relative Relative Importance Importance Importance of ofCriteria Criteria of Criteria and and Factors and Factors Factors 3.1. The Relative Importance of Criteria and Factors TableTableTable 5 5and and 5 Figureand Figure Figure 3 3show show 3 show the the results theresults results of of the theof AHP theAHP AHPsurvey. survey. survey. With With Withrespect respect respect to to the theto results theresults results of of the theof the Tableweightingsweightings5 andweightings Figure of of the theof3 six theshowsix criteria, sixcriteria, thecriteria, “site results“site “sitecontext” context” ofcontext” the ra ranked AHPnked ranked as as survey.the theas most themost most Withimportant important important respect factor factor factor to of of thelandscape landscapeof resultslandscape of the weightingssustainability,sustainability,sustainability, of the representing representing six representing criteria, about about “site about 21.0% 21.0% context” 21.0% of of the the of total ranked thetotal totalcertification, certification, ascertification, the mostfollowed followed followed important by by “soil “soilby “soiland factorand vegetation,”and vegetation,” ofvegetation,” landscape sustainability,withwith witha representingaweighting weighting a weighting of of about aboutabout of about 19.7%. 19.7%. 21.0% 19.7%. The The of weightings theThe weightings totalweightings certification, of of these these of these two two criteriatwo followed criteria criteria represented represented by represented “soil more and more more vegetation,”than than than40% 40% of40% of withof thethe total. thetotal. total. The The Theweightings weightings weightings of of the theof “maintenance” the“maintenance” “maintenance” and and and“water” “water” “water” criteria criteria criteria were were were17.9% 17.9% 17.9% and and and16.7%, 16.7%, 16.7%, a weightingrespectively.respectively. ofrespectively. about “Health19.7%. “Health “Health Theand and weightingswellbeing”and wellbeing” wellbeing” (14.4%) of(14.4%) these(14.4%) and and two “materials”and “materials” criteria “materials” represented (10.3%) (10.3%) (10.3%) were were more wereevaluated evaluated evaluated than 40%as as having havingas of having the total. The weightingsrelativelyrelativelyrelatively of low thelow importance. low “maintenance”importance. importance. and “water” criteria were 17.9% and 16.7%, respectively. “Health and wellbeing”WithWith (14.4%) Withregard regard regard to and to the the to “materials”“site the“site “sitecontext” context” context” (10.3%)category, category, category, were “con “con serve“con evaluatedserveserve and and restore and restore as restore having habitats” habitats” habitats” relatively (0.320) (0.320) (0.320) was was low foundwas found importance. found to to to bebe the thebe most themost mostimportant, important, important, followed followed followed by by “integrated “integratedby “integrated desi design design process” process”gn process” (0.301), (0.301), (0.301), “eco “eco-friendly “eco-friendly-friendly layout layout layout planning” planning” planning” (0.243),(0.243),(0.243), and and “brownfieldand “brownfield “brownfield project” project” project” (0.136). (0.136). (0.136). Within Within Within the the “soil the“soil “soiland and vegetation”and vegetation” vegetation” category, category, category, “protect “protect “protect plant plant plant communities”communities”communities” (0.283) (0.283) (0.283) was was foundwas found found to to be be tothe thebe most themost mostimportant, important, important, followed followed followed by by “optimize “optimizeby “optimize biomass” biomass” biomass” (0.237) (0.237) (0.237) andand “manageand “manage “manage healthy healthy healthy soils” soils” soils” (0.190). (0.190). (0.190). “Restore “Restore “Restore aquatic aquatic aquatic ecosystems” ecosystems” ecosystems” (0.431) (0.431) (0.431) was was evaluatedwas evaluated evaluated as as having havingas having higherhigherhigher importance importance importance within within within the the “water” the“water” “water” category category category than than than“natural/permeable “natural/permeable “natural/permeable areas” areas” areas” (0.359) (0.359) (0.359) and and and “rainwater“rainwater“rainwater management” management” management” (0.210). (0.210). (0.210). Among Among Among the the items theitems items in in the inthe “health the“health “health and and andwellbeing” wellbeing” wellbeing” category, category, category, “protection“protection“protection of of cultural culturalof cultural heritage” heritage” heritage” (0.520) (0.520) (0.520) had had ahad acons cons a iderablyconsiderablyiderably higher higher higher weight weight weight than than than“support “support “support physical physical physical activity”activity”activity” (0.251) (0.251) (0.251) and and “supportand “support “support resting resting resting and and socializing”and socializing” socializing” (0.230), (0.230), (0.230), emphasizing emphasizing emphasizing the the importance theimportance importance of of of preservingpreservingpreserving the the history thehistory history and and cultureand culture culture of of the theof existing theexisting existing site. site. Withinsite. Within Within the the materials thematerials materials category, category, category, “use “use “usegreen- green- green- certifiedcertifiedcertified facilities” facilities” facilities” (0.431) (0.431) (0.431) had had a had highera higher a higher weight weight weight than than “usethan “use “userecycled recycled recycled materials” materials” materials” (0.353). (0.353). (0.353). The The item The item ofitem of “use “use of “use regionalregionalregional materials” materials” materials” (0.217) (0.217) (0.217) had had the had the lowest thelowest lowest weight. weight. weight.
TableTableTable 5. 5.Weights Weights 5. Weights of of assessment assessment of assessment criteria criteria criteria and and factors. and factors. factors.
Criteria.Criteria.Criteria. FactorsFactorsFactors LocalLocal Local Local Local Local LocalLocal Local Local Local Local Global GlobalGlobal Global GlobalGlobal ContentContentContent ContentContentContent RankRank Rank Weight WeightWeight RankRank Rank WeightWeight Weight Rank Rank Rank Weight WeightWeight ConserveConserveConserve and and restore and restore restore habitats habitats habitats 1 1 1 0.32 0.32 0.32 5 5 5 0.067 0.067 0.067 IntegratedIntegratedIntegrated design design design process process process 2 2 2 0.301 0.301 0.301 6 6 6 0.063 0.063 0.063 SiteSite context Sitecontext context 1 1 1 0.210 0.210 0.210 Eco-friendlyEco-friendlyEco-friendly layout layout layout planning planning planning 3 3 3 0.243 0.243 0.243 9 9 9 0.051 0.051 0.051 BrownfieldBrownfieldBrownfield project project project 4 4 4 0.136 0.136 0.136 18 18 18 0.029 0.029 0.029 ProtectProtectProtect plant plant plantcommunities communities communities 1 1 1 0.2830.283 0.283 8 8 8 0.0560.056 0.056 OptimizeOptimizeOptimize biomass biomass biomass 2 2 2 0.2370.237 0.237 1010 10 0.0470.047 0.047 SoilSoil &Soil & & 2 2 2 0.1970.197 0.197 Reuse/recycleReuse/recycleReuse/recycle topsoil topsoil topsoil 3 3 3 0.1900.190 0.190 1212 12 0.0360.036 0.036 vegetationvegetationvegetation UseUse nativeUse native native plants plants plants 4 4 4 0.1680.168 0.168 1616 16 0.0330.033 0.033 GreenGreenGreen wall/green wall/green wall/green roof roof roof 5 5 5 0.1310.131 0.131 1919 19 0.0260.026 0.026 MonitoringMonitoringMonitoring plan plan plan 1 1 1 0.582 0.582 0.582 1 1 1 0.104 0.104 0.104 MaintenanceMaintenanceMaintenance 3 3 3 0.179 0.179 0.179 Long-termLong-termLong-term management management management plan plan plan 2 2 2 0.418 0.418 0.418 3 3 3 0.075 0.075 0.075 WaterWaterWater 4 4 4 0.167 0.167 0.167 Restore Restore Restore aquatic aquatic aquatic ecosystems ecosystems ecosystems 1 1 1 0.431 0.431 0.431 4 4 4 0.072 0.072 0.072 Sustainability 2020, 12, 301 8 of 15
Table 5. Weights of assessment criteria and factors.
Criteria. Factors Local Local Local Local Global Global Content Content Rank Weight Rank Weight Rank Weight Conserve and restore 1 0.32 5 0.067 habitats Site 1 0.210 context Integrated design process 2 0.301 6 0.063 Eco-friendly layout 3 0.243 9 0.051 planning Brownfield project 4 0.136 18 0.029 Protect plant 1 0.283 8 0.056 communities Soil & 0.197 Optimize biomass 2 0.237 10 0.047 vegetation 2 Reuse/recycle topsoil 3 0.190 12 0.036 Use native plants 4 0.168 16 0.033 Green wall/green roof 5 0.131 19 0.026 Monitoring plan 1 0.582 1 0.104 Maintenance 3 0.179 Long-term management 2 0.418 3 0.075 plan Restore aquatic 1 0.431 4 0.072 ecosystems Water 4 0.167 Natural/permeable areas 2 0.359 7 0.06 Rainwater management 3 0.210 15 0.035 Protect cultural heritage 1 0.520 2 0.075 Health & 5 0.144 wellbeing Support physical activity 2 0.251 14 0.036 Support resting and 3 0.230 17 0.033 socializing Use green-certified 1 0.431 11 0.044 facilities Materials 6 0.103 Use recycled materials 2 0.353 13 0.036 Use regional materials 3 0.217 20 0.022
With regard to the “site context” category, “conserve and restore habitats” (0.320) was found to be the most important, followed by “integrated design process” (0.301), “eco-friendly layout planning” (0.243), and “brownfield project” (0.136). Within the “soil and vegetation” category, “protect plant communities” (0.283) was found to be the most important, followed by “optimize biomass” (0.237) and “manage healthy soils” (0.190). “Restore aquatic ecosystems” (0.431) was evaluated as having higher importance within the “water” category than “natural/permeable areas” (0.359) and “rainwater management” (0.210). Among the items in the “health and wellbeing” category, “protection of cultural heritage” (0.520) had a considerably higher weight than “support physical activity” (0.251) and “support resting and socializing” (0.230), emphasizing the importance of preserving the history and culture of the existing site. Within the materials category, “use green-certified facilities” (0.431) had a higher weight than “use recycled materials” (0.353). The item of “use regional materials” (0.217) had the lowest weight. Sustainability 2020, 12, x FOR PEER REVIEW 8 of 14
Natural/permeable areas 2 0.359 7 0.06 Rainwater management 3 0.210 15 0.035 Protect cultural heritage 1 0.520 2 0.075 Health & Support physical activity 2 0.251 14 0.036 5 0.144 wellbeing Support resting and 3 0.230 17 0.033 socializing Use green-certified facilities 1 0.431 11 0.044 Materials 6 0.103 Use recycled materials 2 0.353 13 0.036 Sustainability 2020, 12, 301 Use regional materials 3 0.217 20 0.022 9 of 15
Site context Soil & vegetation Conserve and restore 0.32 Protect plant communities 0.283 habitats Integrated design Optimize biomass 0.237 0.301 process Manage healthy soils 0.19 Eco-friendly layout 0.243 planning Use native plants 0.168 Greenwall/ greenroof Brownfield projection 0.136 0.131 0 0.1 0.2 0.3 0 0.1 0.2 0.3 0.4
Water Maintenance Restore aquatic ecosystems 0.431 Monitoring plan 0.582 Natural/ permeable areas Long-term management 0.359 0.418 plan Rainwater management 0.21 0 0.2 0.4 0.6 0.8
0 0.1 0.2 0.3 0.4 0.5
Materials Health & wellbeing Use green-certified 0.431 Protect cultural heritage 0.52 facilities
Support physical 0.251 Use recycled materials 0.353 activity Support resting and 0.23 Use regional materials socializing 0.217
0 0.1 0.2 0.3 0.4 0.5 0.6 0 0.1 0.2 0.3 0.4 0.5
FigureFigure 3. 3.Relative Relative weights of assessment assessment factors factors of of AHP. AHP.
3.2.3.2. Comparison Comparison of of Importance Importance in in Di Differentfferent ProfessionsProfessions WeWe investigated investigated the the di differencesfferences ofof prioritiespriorities between the the landscape landscape architects architects group group and and the the engineersengineers/architects/architects group. group. Landscape Landscape architects architects evaluated evaluated “soil “soil and vegetation”and vegetation” as the mostas the important most inimportant the assessment, in the while assessment, the engineers while /thearchitects engineers/ar groupchitects evaluated group “site evaluated context” “site as the context” most important. as the Formost the landscapeimportant. architectsFor the landscape group, “site architects context” group, came “site second context” in the came weighting, second followed in the weighting, by “water,” “maintenance,”followed by “water,” “health “maintenance,” and wellbeing,” “health and “materials.” and wellbeing,” On the and contrary, “materials.” the order On the of contrary, importance the for order of importance for the engineers group was “maintenance,” “health and wellbeing,” “soil and the engineers group was “maintenance,” “health and wellbeing,” “soil and vegetation,” “water,” and vegetation,” “water,” and “materials” (Table 6). Figure 4 illustrates the differences of importance “materials” (Table6). Figure4 illustrates the di fferences of importance between the two groups. between the two groups. Table 6. Comparison of rankings between landscape architects and engineers/architects groups.
Total (n = 141) Landscape Architects (n = 70) Engineers/Architects (n = 71) Rank Category Weighting Category Weighting Category Weighting 1 Site context 0.210 Soil/vegetation 0.235 Site context 0.211 2 Soil/vegetation 0.197 Site context 0.206 Maintenance 0.185 3 Maintenance 0.179 Water 0.171 Health/wellbeing 0.165 4 Water 0.167 Maintenance 0.171 Soil/vegetation 0.164 5 Health/wellbeing 0.144 Health/wellbeing 0.123 Water 0.162 6 Materials 0.103 Materials 0.094 Materials 0.112 Sustainability 2020, 12, x FOR PEER REVIEW 9 of 14
Table 6. Comparison of rankings between landscape architects and engineers/architects groups.
Total Landscape Architects Engineers/Architects Rank (n = 141) (n = 70) (n = 71) Category Weighting Category Weighting Category Weighting 1 Site context 0.210 Soil/vegetation 0.235 Site context 0.211 2 Soil/vegetation 0.197 Site context 0.206 Maintenance 0.185 3 Maintenance 0.179 Water 0.171 Health/wellbeing 0.165 4 Water 0.167 Maintenance 0.171 Soil/vegetation 0.164 Sustainability5 Health/wellbeing2020, 12, 301 0.144 Health/wellbeing 0.123 Water 0.16210 of 15 6 Materials 0.103 Materials 0.094 Materials 0.112
FigureFigure 4. 4.Discrepancy Discrepancy ofof importanceimportance inin landscapelandscape sustainability sustainability criteria. criteria. 3.3. Application of the Landscape Sustainability Model to G-SEED-Certified Projects 3.3. Application of the Landscape Sustainability Model to G-SEED-Certified Projects Table7 shows the results of applying the weightings derived from the AHP to the three Table 7 shows the results of applying the weightings derived from the AHP to the three G-SEED- G-SEED-certified projects. The AHP weightings were multiplied by mean scores of experts for certified projects. The AHP weightings were multiplied by mean scores of experts for each item, and each item, and the ratio of individual weighted scores out of total scores was calculated. Total weighted the ratio of individual weighted scores out of total scores was calculated. Total weighted point of point of each project was 3.43, 2.52, and 2.56. There was also a big difference in the level of sustainability each project was 3.43, 2.52, and 2.56. There was also a big difference in the level of sustainability among items and criteria within a single project. among items and criteria within a single project. LH-HQ obtained higher scores than the other two projects mainly in “maintenance” and LH-HQ obtained higher scores than the other two projects mainly in “maintenance” and “health/wellbeing” criteria. By item, the scores were high in “monitoring plan” (0.46), “long-term “health/wellbeing” criteria. By item, the scores were high in “monitoring plan” (0.46), “long-term management plan” (0.32), and “natural/permeable areas” (0.30). This is because the project had the management plan” (0.32), and “natural/permeable areas” (0.30). This is because the project had the locational benefit of securing natural soil and provided many exercise facilities/rest areas. It obtained locational benefit of securing natural soil and provided many exercise facilities/rest areas. It obtained high scores in the maintenance criteria, especially since there was a landscape maintenance plan. high scores in the maintenance criteria, especially since there was a landscape maintenance plan. Renaissance Hotel showed high scores in “monitoring plan” (0.32) and “protection of cultural heritage” Renaissance Hotel showed high scores in “monitoring plan” (0.32) and “protection of cultural (0.23) because it preserved architectural history in a high-density area in downtown Seoul. The Sejong heritage” (0.23) because it preserved architectural history in a high-density area in downtown Seoul. construction showed relatively high scores in “support resting and socializing” (0.13) and “support The Sejong construction showed relatively high scores in “support resting and socializing” (0.13) and physical activity” (0.14). Being a housing complex, it obtained relatively high scores in the “health and “support physical activity” (0.14). Being a housing complex, it obtained relatively high scores in the wellbeing” category, which benefits residents more directly compared to other items. “health and wellbeing” category, which benefits residents more directly compared to other items. As a result of comparing the mean weighted scores in the six criteria (Figure5), it was found that the distribution of the scores in each category shared a similar trend among the three projects. In other words, “maintenance” showed relatively higher mean scores than the other criteria. On the other hand, “water” showed lower mean scores than the other criteria at 0.12, 0.09, and 0.10, respectively. Accordingly, it was discovered that the G-SEED-certified projects in Korea are concentrated on certain criteria in terms of landscape sustainability, whereas other criteria are considered relatively less important. Sustainability 2020, 12, 301 11 of 15
Table 7. Application of developed assessment factors to Green Standard for Energy and Environmental Design certified projects.
LH-HQ Renaissance Sejong Weight Criteria Index Weigh-Ted Weigh-Ted Weigh-Ted Point % Point % Point % Point Point Point Conserve and restore habitats 0.067 2.11 0.14 4.1% 2.22 0.15 5.9% 1.89 0.13 4.9% Site context Integrated design process 0.063 4.22 0.27 7.7% 3 0.19 7.5% 3.22 0.20 7.9% Eco-friendly layout planning 0.051 4 0.20 5.9% 2.11 0.11 4.3% 3.11 0.16 6.2% Brownfield project 0.029 3.67 0.11 3.1% 2.33 0.07 2.7% 2.56 0.07 2.9% Protect plant communities 0.056 2.33 0.13 3.8% 2.78 0.16 6.2% 2.11 0.12 4.6% Optimize biomass 0.047 4.22 0.20 5.8% 3 0.14 5.6% 3.67 0.17 6.7% Soil/vege- tation Manage healthy soils 0.036 2.44 0.09 2.6% 1.78 0.06 2.5% 1.89 0.07 2.7% Use native plants 0.033 3.67 0.12 3.5% 2.89 0.10 3.8% 3.22 0.11 4.1% Green wall/green roof 0.026 4.11 0.11 3.1% 3.11 0.08 3.2% 3.22 0.08 3.3% Monitoring plan 0.104 4.44 0.46 13.5% 3.11 0.32 12.8% 3 0.31 12.2% Mainte- nance Long-term management plan 0.075 4.22 0.32 9.2% 2.78 0.21 8.3% 2.67 0.20 7.8% Restore aquatic ecosystems 0.072 N.A. N.A. N.A. N.A. N.A. N.A. N.A. N.A. N.A. Water Natural/permeable areas 0.06 5 0.30 8.7% 3 0.18 7.1% 3 0.18 7.0% Rainwater management 0.035 3.11 0.11 3.2% 2.44 0.09 3.4% 2.89 0.10 3.9% Protection of cultural heritage 0.075 2.67 0.20 5.8% 3.11 0.23 9.2% 1.22 0.09 3.6% Health/wellbeing Support physical activity 0.036 4.78 0.17 5.0% 2.33 0.08 3.3% 3.89 0.14 5.5% Support resting and 0.033 4.67 0.15 4.5% 3 0.10 3.9% 4 0.13 5.2% socializing Use green-certified facilities 0.044 4 0.18 5.1% 2.78 0.12 4.9% 3.33 0.15 5.7% Materials Use recycled materials 0.036 3 0.11 3.1% 2.22 0.08 3.2% 2.33 0.08 3.3% Use regional materials 0.022 3.22 0.07 2.1% 2.56 0.06 2.2% 2.89 0.06 2.5% Total 1 68.61 3.43 100.0% 50.55 2.52 100.0% 54.11 2.56 100.0% Sustainability 2020, 12, 301 12 of 15 Sustainability 2020, 12, x FOR PEER REVIEW 11 of 14
FigureFigure 5.5. Results of application ofof assessmentassessment system.system. 4. Discussion 4. Discussion The following discussions can be had to develop assessment factors to objectively evaluate The following discussions can be had to develop assessment factors to objectively evaluate landscape sustainability. landscape sustainability. First, as a result of applying the AHP to the newly derived items, “site context” and “soil and First, as a result of applying the AHP to the newly derived items, “site context” and “soil and vegetation” showed the highest weightings in the main criteria, while “monitoring plan” showed the vegetation” showed the highest weightings in the main criteria, while “monitoring plan” showed the highest weighting in the sub-criteria, followed by “protection of cultural heritage” and “long-term highest weighting in the sub-criteria, followed by “protection of cultural heritage” and “long-term management plan.” This result is similar to that of a study on factors for planning green apartment management plan.” This result is similar to that of a study on factors for planning green apartment houses [21], which showed the highest importance in “principle of efficient use of land,” and that of a houses [21], which showed the highest importance in “principle of efficient use of land,” and that of study on improving the Green Building Certification System for sustainable urban development [16], a study on improving the Green Building Certification System for sustainable urban development which showed the highest importance in “site selection and preservation.” [16], which showed the highest importance in “site selection and preservation.” There were also some differences between the items considered important in overseas landscape There were also some differences between the items considered important in overseas landscape sustainability rating systems and the results of the Korean working-level assessment of importance. sustainability rating systems and the results of the Korean working-level assessment of importance. For example, items such as “select brownfields or grayfields for redevelopment,” “preservation of For example, items such as “select brownfields or grayfields for redevelopment,” “preservation of soil and prevention of soil disturbance,” and “use recycled materials and regional materials” had a soil and prevention of soil disturbance,” and “use recycled materials and regional materials” had a high distribution of scores in the SITES but showed low importance in Korea. Items not covered in high distribution of scores in the SITES but showed low importance in Korea. Items not covered in G-SEED, such as “protection of cultural heritage,” “user health and wellbeing,” “monitoring plan,” and G-SEED, such as “protection of cultural heritage,” “user health and wellbeing,” “monitoring plan,” “long-term management plan,” also turned out to be important, indicating that there is an emphasis on and “long-term management plan,” also turned out to be important, indicating that there is an comprehensive approaches, such as integrated planning and the design process. emphasis on comprehensive approaches, such as integrated planning and the design process. In terms of sustainability assessment items, there was not much difference from the results of In terms of sustainability assessment items, there was not much difference from the results of studies that used different methods from the AHP. In a study that conducted a survey on users of a studies that used different methods from the AHP. In a study that conducted a survey on users of a residential complex [41] and studies focused on field surveys [3,28], “site selection” was considered residential complex [41] and studies focused on field surveys [3,28], “site selection” was considered an important item, along with “recycling of topsoil” and “use of rainwater.” The AHP model has the an important item, along with “recycling of topsoil” and “use of rainwater.” The AHP model has the benefit of having the importance of assessment items determined by the experience and expertise of benefit of having the importance of assessment items determined by the experience and expertise of field experts and thus has greater value in terms of field applicability compared to other studies based field experts and thus has greater value in terms of field applicability compared to other studies based only on a literature review or user survey. only on a literature review or user survey. Second, G-SEED is mostly focused on buildings. There is a perception gap between architects Second, G-SEED is mostly focused on buildings. There is a perception gap between architects and landscape architects in the calculation of weightings for the landscape sustainability assessment and landscape architects in the calculation of weightings for the landscape sustainability assessment items. Landscape architects gave higher weightings than architects to “soil and vegetation.” This is items. Landscape architects gave higher weightings than architects to “soil and vegetation.” This is because they directly handle plants and deal with planting, and thus, they better understand and because they directly handle plants and deal with planting, and thus, they better understand and emphasize this item. This is similar to the finding of previous research [11] on the perception gap emphasize this item. This is similar to the finding of previous research [11] on the perception gap in in landscape–architecture importance, showing that multilayered planting structure and diversity landscape–architecture importance, showing that multilayered planting structure and diversity of of plant species score high in landscape. It is also similar to the actual sustainability strategies and plant species score high in landscape. It is also similar to the actual sustainability strategies and methods of the SITES in the US for soil, vegetation, water circulation management, and landscape methods of the SITES in the US for soil, vegetation, water circulation management, and landscape materials [4], implying that it is necessary to develop objective landscape assessment items that have materials [4], implying that it is necessary to develop objective landscape assessment items that have been overlooked in the existing building assessment criteria. been overlooked in the existing building assessment criteria. Third, the results of applying this assessment system to three G-SEED certified projects showed that while there was a slight difference in score overall, similar trends with criteria and factors are Sustainability 2020, 12, 301 13 of 15
Third, the results of applying this assessment system to three G-SEED certified projects showed that while there was a slight difference in score overall, similar trends with criteria and factors are considered important from a landscape sustainability perspective. After analyzing the weighted average score for each field, we found that “maintenance” had the highest score with a relatively low score in “water” and “materials” in the three projects. These results indicate a need for more interest and effort in sustainable water management and material usage in Korea. In addition, the result revealed that Renaissance had a relatively high score of ‘protection of cultural heritage’, which highlighted the efforts to preserve architectural history in creating outdoor space. Considering these results derived from this assessment system, the assessment model of this study can be instrumental in supplementing G-SEED, which has relatively fewer assessment criteria for outdoor spaces. That is, a landscape-centered assessment system with various items would be useful in identifying outdoor sustainability issues and providing concrete solutions for the issues [42]. Therefore, continued efforts will be required to establish an assessment system for landscape sustainability that suits the Korean local context.
5. Conclusions Many issues have been raised, including the notion that the landscape items of Korean sustainability certification are relatively scant and limited in terms of assessment and effectiveness, and thus, urgently require supplementation [3,4,10]. Therefore, to develop independent assessment factors to objectively assess landscape sustainability, this study derived items—including ecological value of the existing site, biotope creation, soil, vegetation, and water circulation management—not included in the existing assessment systems focusing on buildings and rated their importance using the AHP. The results showed that the existing G-SEED is inadequate for landscape assessment in many ways, and thus, there is a need for a differentiated certification system for landscape sustainability. Moreover, presenting the purpose and technology should be considered, rather than merely focusing on rating quantitative achievement, as should making assessment in terms of landscape performance, such as various creative sustainability strategies or technologies. In Korea, preliminary certification is often obtained at the end of the designing stage and main certification at the point of completion, for incentives. Thus, even though it is important in terms of reality, there are limitations in applying for certification in terms of post-occupancy evaluation or from the users’ perspective. It is necessary to establish the system to evaluate sustainability in the entire process of the project, including design, construction, and maintenance. However, this study’s significance lies in deriving assessment items that are applicable to landscape, instead of using the existing system in Korea that is focused on buildings, calculating weightings, and analyzing the trend based on specific cases of application, thereby presenting the possibility of developing a rational landscape assessment system.
Author Contributions: H.-S.L. designed the research and analyzed the data; E.-Y.P. designed the research and collected the field data. Both authors read and approved the final manuscript. All authors have read and agreed to the published version of the manuscript. Funding: This research was funded by the Kyungpook National University Research Fund, 2017. Conflicts of Interest: The authors declare no conflict of interest. The founding sponsors had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.
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