Early stage decision support for sustainable building renovation – A review

Building and Environment 103 (2016) 165e181

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Building and Environment journal homepage: www.elsevier.com/locate/buildenv

Early stage decision support for sustainable building renovation e A review Anne N. Nielsen a, *, Rasmus L. Jensen b, Tine S. Larsen b, Søren B. Nissen c a

Department of Energy and Environment, University College of Northern Denmark (UCN), Sofiendalsvej 60, 9200 Aalborg SV, Denmark Department of Civil Engineering, Aalborg University, Sofiendalsvej 9-11, 9200 Aalborg SV, Denmark c Architectural Technology and Construction Management, University College of Northern Denmark (UCN), Sofiendalsvej 60, 9200 Aalborg SV, Denmark b

a r t i c l e i n f o

a b s t r a c t

Article history: Received 27 February 2016 Received in revised form 4 April 2016 Accepted 11 April 2016 Available online 13 April 2016

Decision support tools for building renovation are important as assistance to professional building owners when setting goals for sustainability, and for making sure that the objectives are met throughout the design process, both when renovating a single building or choosing renovation actions within a building portfolio. Existing literature on decision support tools applicable in the pre-design and design phase of renovation projects have been reviewed, with the aim of providing a state-of-the-art overview. The paper categorizes the tools into six areas in which they can support the decision makers in the renovation process: in setting sustainability goals, weighting criteria, building diagnosis, generation of design alternatives, estimation of performance, and in the evaluation of design alternatives. These six areas are unfolded throughout the paper, along with examples and discussion of the applicability of the tools in the corresponding areas of the renovation process. The study presents perspectives on the future development of decision support tools in renovation projects, including the aspect of renovating multiple buildings. Areas for future research are suggested, such as emphasizing the aspect of choosing and weighting sustainability criteria, providing explicit guidelines for screening the existing building(s), and prioritizing renovation actions within a building portfolio. © 2016 Elsevier Ltd. All rights reserved.

Keywords: Decision support tools Multi-criteria decision-making Sustainability assessment Existing buildings

1. Introduction Buildings are responsible for more than 40% of the energy use worldwide and for one-third of global greenhouse gas emissions [1], which entails increasing attention on sustainable development within the construction industry. In Europe, actions have been made to reduce energy consumption and carbon dioxide emissions in the building sector and the built environment [2e4]. In Denmark, the government has a long-term objective of being free of fossil fuels by 2050, and an important element in this is improving energy efficiency [5]. In 2014, the Danish government presented a strategy for energy renovation of the existing building stock in Denmark towards 2050, emphasizing the potential for building renovation regarding reducing energy consumption and CO2 emissions, without compromising environmental, social and economic quality [6].

* Corresponding author. E-mail addresses: [email protected] (A.N. Nielsen), [email protected] (R.L. Jensen), tsl@ civil.aau.dk (T.S. Larsen), [email protected] (S.B. Nissen). http://dx.doi.org/10.1016/j.buildenv.2016.04.009 0360-1323/© 2016 Elsevier Ltd. All rights reserved.

The assessment of the sustainability of buildings has emerged as one of the major issues in the building industry [7]. In 1990, the Building Research Establishment Environmental Assessment Method (BREEAM, UK) was developed as the first comprehensive building performance assessment method [7], followed by other first generation methods such as LEED (USA), CASBEE (Japan), GreenStar (Australia) and HQE (France). Common for these is that the main focus is on the building's influence on the environment and the use of energy [8]. Second generation assessment tools such as DGNB (Germany) and LEnSE (EU) also include economic, sociocultural, and technical aspects, and deal with the entire lifecycle of the building [8]. The different assessment methods have been adapted to local climatic conditions, rules, and regulations [9], as well as vary in their weighting of categories, ratings, flexibility and assessed building typologies [10]. Several assessment tools have been adapted for renovation purposes (e.g. BREEAM, LEED, CASBEE, and DGNB) [11], along with assessment tools specifically developed for renovation, such as reSBToolCZ [12]. The comprehensive nature of the assessment methods makes it challenging to integrate all of the assessment criteria in the early design phase, as it is both time consuming and the level of information needed to make proper

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simulations and calculations is insufficient at that stage. In a building renovation process, countless decisions are made throughout the different phases; from the initial decisions on which buildings to renovate, to the design of renovation scenarios, selection among design alternatives, to construction, operation, usage, and finally demolition or reuse. Multi-criteria decisionmaking is a branch of decision-making that deals with the process of making decisions with multiple, often conflicting, objectives [13]. The use of multi-criteria decision-making methods has gained popularity in building renovation, which has led to the development of several decision support tools and methods, varying in complexity and applicability. The aim of this paper is to provide a state-of-the-art overview of the development of decision support tools applicable in the predesign and design phase of renovation projects and to identify potential areas for future research. The tools have been categorized and discussed in relation to where in the renovation process they can support the decision maker. A structured approach has been undertaken to identify representative literature within the scope of the review. Searches for peer-reviewed journal articles, dissertations, and conference proceedings were conducted using the Scopus database among others. Peer-reviewed literature has been the primary source of information; however, relevant books, reports, and websites have been included to get an extensive understanding of the current development in the field. The inclusion criteria for the tools in the review have been that they deal with multiple criteria (two at minimum) and are applicable to renovation projects. The level of detail provided about the tools in the review represents the level of detail in the literature. The review is structured as follows: the introduction followed by an overview of the renovation process and the existing decision support tools found in the literature. The tools are divided into six categories reflecting the areas in which they can substantiate the renovation process: goal setting, weighting of criteria, building diagnosis, generation of design alternatives, estimation of performance, and finally evaluation of design alternatives. The six areas are unfolded throughout the review, along with examples and discussion of the tools' applicability in the corresponding areas. Perspectives on future development and use of decision support tools in renovation projects are presented, including the aspect of renovating multiple buildings. Major findings are summarized in the concluding section, including suggestions for future research. Other reviews of decision support tools in relation to building renovation have previously been published. Kolokotsa et al. [14] reviewed methods used on energy efficiency and energy management in buildings and categorized the tools in relation to their methodology, and Ferreira et al. [15] presented a division based on the common aims and objectives of the decision support tools. Thuvander et al. [11] made a survey of decision-making procedures and existing decision support tools used by stakeholders in relation to the renovation of existing buildings, with emphasis on the preliminary investigation. This paper contributes by suggesting a new categorization in relation to the applicability of each tool in different areas of the pre-design and design stage of the renovation process. 1.1. Terminology In this paper, the term “renovation” is used as a general term for improvements of the performance of existing buildings, ranging from middle to major interventions. “Sustainable renovation” is used to underline a holistic approach where environmental, social, and economic aspects are encompassed in a balanced way. The term “decision support tool” is used to describe any tool or method, which serves the purpose of helping the decision maker in making

more informed decisions when dealing with multiple criteria. “The decision maker” primarily refers to the professional building owner, who has knowledge and experience in the field of building renovation, and has a professional team of specialized advisors and designers. The term “goal” is used to describe long term aims and can be of a general character and not necessarily measurable. “Objectives” is used to describe specific actions or milestones within the general goal while “measures” refers to measurable achievements, qualitative or quantitative. 2. The renovation decision process A renovation process is not far from the process of designing a new building, including the phases of pre-design, design, construction, and operation of the building. However, the main difference is the constraints of having an existing building and building site along with the existing users of the building. Fig. 1 illustrates the overall steps in a renovation project. It should be recognized that the steps in the pre-design and design phase are iterative in nature and that “sub-iterations” take place throughout the process, e.g. in the individual design process of the architect or engineer where design proposals are continuously evaluated. Wang et al. [16] have described the ideal steps in a decisionmaking process as first defining the problem, then identifying objectives and criteria, criteria weighting, generation of alternatives, rating each alternative on each criterion and lastly computing the optimal solution. Ferreria et al. [15] and Alanne [17], for instance, have described the decision-making process in relation to renovation projects. Synthesizing these models with the steps illustrated in Fig. 1, there are six areas where formal decision-making methods can contribute in renovation projects (Fig. 2). 3. Existing decision support tools for building renovation In the reviewed literature, 43 decision support tools that are applicable in the pre-design and design phase of renovation projects have been selected. The majority of these are developed specifically for renovation projects, where others can be used both in existing and new buildings. Lastly, some are developed for new construction but have the potential to be used for renovation. Some tools are developed for specific local contexts and building typologies and, therefore, may not be directly applicable to other contexts or building types. The tools have been divided into the six categories presented in Fig. 2, according to where in the renovation process they can support the decision maker (Table 1). 3.1. Setting the right goals The first key step in the renovation process is defining the goals, objectives, and criteria since all the following phases are adapted to these strategic and important aspects. This strategic area can, in fact, be seen as the rational heart of the entire process [15]. Whether the goal is to renovate a single building or make strategic renovation prioritization within a building portfolio, the point of departure is setting the right objectives, to solve the right problems and find the best alternatives. The objectives can be based on values from the involved stakeholders, or the set of criteria can be fixed from the beginning, leaving the weighting to the decision maker, as seen in several of the reviewed tools. Criteria can be based on existing sustainability assessment methods as the assessment schemes can provide a structured way to incorporate sustainability criteria into the design process. However, these were not originally designed to serve as design guidelines [7], but rather to assess a finished building and, therefore, might be too time-consuming to include at an early stage. However, it should be recognized that, in

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Fig. 1. The building renovation process.

practice, values and objectives of the decision-makers are often developed throughout the design process and that values may not be clear until design alternatives have been generated [61]. Among the reviewed methods, 21% deal with the aspect of setting goals and choosing criteria (Table 2). 5% take their point of departure explicitly in the discussion on objectives among the stakeholders [53,60] where the rest has a fixed set of criteria but leaves the weighting open to being assigned by the involved stakeholders. RENO-EVALUE [60] is a value-based decision support tool that focuses on the different interests and values of the main stakeholders involved in a sustainable building renovation project. The tool is intended as a basis for dialogue among building professionals and building users in the formulation of objectives. Furthermore, it can be used to evaluate a renovation project holistically, according to the sustainability goals of the project. The Total Value Model (in Danish: Totalværdimodellen) [53] is an analysis and process tool aimed towards the building owner, providing a framework for setting strategic objectives for the renovation project. The tool is divided into eight steps, each including

important aspects to consider such as recommendations for documentation, activities, and tools, in relation to economic, environmental, and social values. The model can be used when renovating a single building or when setting goals for renovations within a building portfolio [53]. Other tools include the step of choosing objectives, but do not provide a method to do it. The knapsack model was developed by Alanne [17] with the aim to help designers select the most suitable renovation actions in the conceptual phase of a renovation project. The model does not directly deal with how to choose criteria but states that these are selected by the design team. The criteria are structured in a decision-tree where the main criteria indicate general, strategic objectives, sub-criteria with more concrete issues, and the lowest level of the tree represents criteria measures that can be either quantitative (e.g. annual energy use) or qualitative (e.g. aesthetics) (Fig. 3). The measures, or indicators, serve as the yardstick for evaluating to which extent the alternatives meet the overall goal [17]. Martinaitis et al. [41] developed a two-factor method, with which the decision maker can establish goals

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Fig. 2. Six areas where formal decision-making methods can contribute in renovation projects.

within economy and energy consumption. Wang and Zeng [62] presented a method for reuse selection of historic buildings where an interdisciplinary team defines the objectives. Lastly, some tools suggest criteria, but allow the flexibility of assigning weights by the stakeholders, as seen in e.g. BR-DSS [30], MDCM-23 [63], and the method for Multivariant Design and Multiple Criteria Analysis proposed by Kaklauskas et al. [32]. 3.1.1. Sustainability criteria included in the reviewed tools The sustainability criteria and objectives included in the reviewed tools have been divided into three categories: Social, Environmental and Economic Sustainability (Table 3), based on the components of sustainable development derived from the Rio Declaration from 1992 [64]. The Social Sustainability category includes aspects of indoor environmental quality, architectural quality, functionality, quality of life, employment, and cultural aspects. The Environmental Sustainability category includes aspects of energy and environmental impact, and use of resources. The Economic Sustainability criteria category includes cost related aspects of both construction and operation. The level of detail of the objectives and criteria in Table 3 reflects the different levels of detail described in the literature; some indicate overall objectives and others provide a detailed list of included criteria, sub-criteria, and measures. Furthermore, as the tools are designed to be used in different local contexts, with different building typologies, and use individual criteria weights, they are not entirely comparable. In the cases where sub-criteria are specified, these are noted in brackets after the main criteria. The division of the criteria and objectives shows that 40% of the 43 tools include, or have the option of including, criteria from all three categories. 63% of the tools include criteria from the Social Sustainability category, a majority of these being aspects of indoor environmental quality. Economic Sustainability criteria are included in 72% of the tools. The environmental quality criteria are represented in 81% of the reviewed tools, making this the highest represented category. 3.2. The weighting process The weighting process is necessary to determine the relative importance of the criteria, and thereby their impact on the final design. There are two overall approaches: equal weights, which do

not allow prioritization, and rank-order weights, which can be either subjective (based on the preferences of the decision makers), objective (based on quantitative measured data), or both [65]. The reviewed tools which include the option of weighting criteria are all based on rank-order weighting methods, which provide the freedom of prioritizing a set of criteria to a particular renovation context. Table 4 shows the weighting methods used in the reviewed tools. The most used weighting method within this review is the Analytic Hierarchy Process (AHP) [22,37,43,48,58] which is widely used in the architectural, engineering, and construction industry [70], followed by the Grading Method in popularity [17,63]. AHP was developed by Saaty [71] to prioritize criteria through pairwise comparison in order to find the best alternative based on the judgments of the decision maker. The decision problem is structured into a hierarchy with the overall goal at the top, followed by the objectives or criteria groups, then sub-criteria, and usually a set of alternatives at the lowest level. Elements and level can be added to fit the decision problem as close as possible. This is done to ensure that the elements are compared on the same level and thus in a meaningful way. Next step is to construct pairwise comparison matrices where the elements on the same level are compared to each other with a scale of numbers from 1 to 9, where 1 is given when two elements are of equal importance, and 9 represents extreme importance to one element in comparison with another. The other element is then assigned the reciprocal 1/9, which indicates that it is nine times less important than the other. The criteria weights are then normalized and synthesized from the matrix [71,72]. In that way, the relative importance of both qualitative and quantitative criteria can be determined based on the judgments of the decision maker. The Grading Method is a simple method for assigning weight where the most important criterion receives the grade 10, and all the other criteria on the same level are graded from 1 to 10 depending on their relative importance to the most important criteria. The weights are then normalized to range between 0 and 1 so that the sum of the weights is one. This procedure is then repeated for each level in the criteria tree [17]. Both AHP and the Grading Method serve the purpose of assigning weights to criteria on the same hierarchical level by comparing the criteria to each other. In that way, an individual measuring scale is established, and it is possible to prioritize among

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Table 1 43 decision support tools applicable in renovation projects. The tools are divided according to where in the renovation project they can support the decision maker. Name of tool

EPIQR MEDIC MCDM-23 TOBUS ORME MOGA GENE_ARCH SST tool XENIOS “Knapsack’” model BR-DSS INVESTIMMO Multivariant design Variable grouping

BEPAS

OLSC

REFLEX

MAMVA, DSSCRP Total value model MultiOpt

Euro. Retro. Advisor

Renobuild RENO-EVALUE

Year Authors/developers 1995 Gorgolewski [18] 1996 Gorgolewski [19] 2000 Jaggs and Palmer [20] 2000 Flourentzou et al. [21] 2000 Balcomb et al. [22] 2002 Flourentzou et al. [23] 2002 Roulet et al. [24] 2002 Wright et al. [25] 2002 Caldas et al. [26,27] 2003 Alanne et al. [28] 2004 Dascalaki et al. [29] 2004 Alanne [17]

Goal setting

Criteria weighting

Building diagnosis

x

Design alternatives Generation

Performance estimation

x

x x x x

x

x x

x

x

x

x

x

x

2004 Zavadskas et al. [30] x 2004 Droutsa et al. [31] 2005 Kaklauskas et al. [32] x

x

x x x

x x x x x x x x

x x

x

x

x

x x x

2005 Pushkar et al. [33]

x

2005 2005 2006 2006 2007 2007 2007 2007 2007 2009 2010 2010 2010 2010 2010 2010 2010 2010 2011

x x x x x x x x x x x x x x

Wang et al. [34] Wetter et al. [35] Zhang et al. [36] Juan et al. [37] Zavadskas et al. [38] Kaklauskas et al. [39] Znouda et al. [40] Martinaitis et al. [41] x Pasanisi et al. [42] Juan et al. [43] Crawford et al. [44] Verbeeck et al. [45] Diakaki et al. [46] Juan et al. [47] Wang et al. [48] x Liu et al. [49] Li et al. [50] Magnier et al. [51] Kanapeckiene et al. [52] 2011 Plan C [53] x

2011 2011 2012 2014

Chantrelle et al. [54] Tsai et al. [55] Bermejo et al. [56] Zimmermann [57]

2014 Medineckiene et al. [58] €rnell et al. [59] 2014 Mjo 2015 Jensen et al. [60] Total:

Design alternatives evaluation

x x x x

x

x x

x x

x

x x

x

x x x

x

x x x x x x x x

x

x

x x

x x

36

5

x 9

14

9

13

Table 2 Tools that include the aspect of goal setting, with either a fixed or non-fixed set of criteria. Name of tool

Year

Authors/developers

Fixed or non-fixed set of criteria

MCDM-23 SST tool ‘‘knapsack’’ model BR-DSS Multivariant design

2000 2003 2004 2004 2005 2007 2010 2011 2015

Balcomb et al. [22] Alanne et al. [28] Alanne [17] Zavadskas et al. [30] Kaklauskas et al. [32] Martinaitis et al. [41] Wang et al. [48] Plan C [53] Jensen et al. [60]

Fixed Fixed Fixed Fixed Open, based on the use of various experts' methods Fixed Fixed Value-based, discussion among stakeholders Value-based, discussion among stakeholders

Total Value Model RENO-EVALUE

both qualitative and quantitative criteria. If the goal is sustainability assessment of the building, or if

sustainability assessment methods are used as design guidelines for the project, criteria and weights are fixed depending on the

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Fig. 3. Criteria tree (adapted from Ref. [17]).

choice of assessment method. One example is DGNB, which uses a weighted sum method where social, economic, environmental, and technical qualities are weighted equally (22,5%), and process quality is weighted 10%. Using a tool for choosing and weighting criteria encourages the stakeholders to consider sustainability aspects at an early stage, which has proven to bring value to the process [73]. In that way, it can create discussion about values and create a deeper understanding of the problem at hand [61]. Whether the criteria should be fixed or open can be discussed. On one hand, a fixed set of criteria narrows down the solution space and provide tangible goals and on the other hand, the criteria may not fit the individual case. Every project is different; stakeholders and political and environmental contexts are different, and, therefore, decision support tools should address this with a level of flexibility. This flexibility is encompassed in several of the existing tools in the possibility of assigning weights to pre-defined criteria. Trade-offs are an inevitable part of any design process, and even if comprehensive building sustainability assessment methods are put into use, trade-offs have to be made along the way. 3.3. Assessing the current state of the building A diagnosis of the existing building should be performed to determine the need for renovation. Assessing the current state of the building after having set up sustainability goals for the project will make the registration process more targeted; however, the diagnosis can also be made before the goal setting. Several tools include this step, and in general, it can be said that the golden line here is the balance between the level of information needed and time available for collecting data about the building. 21% of the reviewed tools describe a method for assessing the current state of a building (Table 5). At the diagnosis stage, available information about the building is collected, and a systematic registration of the degradation state of the building components can be performed, along with a user questionnaire, as seen in e.g. EPIQR [74] and BR-DSS [30]. The EPIQR method [20] is aimed towards apartment building owners who are considering renovation of their building stock. The EPIQR software identifies the most appropriate renovation actions, along with an initial cost estimate, while taking energy and indoor

environmental quality issues into account. Initially, data is collected during a diagnosis survey where questionnaires are distributed to the occupants of the apartments to assess the indoor environmental quality. The physical condition of the apartment buildings is assessed on site, the survey is divided into 50 elements, and each element is graded on a four-point scale from good to poor condition. A walk-through audit addressing the physical state is performed during the site visit to address the energy performance, together with information from historical data such as energy bills [20]. Following the principles of EPIQR, TOBUS [75] was developed to offer a tool for selecting upgrading solutions for office buildings, XENIOS [76] for hotels, and INVESTIMMO [77] for residential buildings, addressing additional criteria compared to the EPIQR method. It assesses the degree of physical degradation and extent of necessary work to renovate the building and the costs [78]. When selecting the deterioration of the building elements, the user can review a detailed description including several photos and sketches representing the different stages. The EPIQR software contains for each building element the general deterioration and corresponding renovation work including cost, future upgrading work as well as related national standards and guidelines [77]. In BR-DSS [30] the information needed may be in a conceptual form (such as digital, textual, photographic, sound, video, graphical, diagrams, graphs, and drawings) and quantitative form [30]. Information about the deterioration and obsolescence is needed, along with the renovation aims and the client's financial situation. The assessment of the current situation is based on questionnaires, building cost indices, tender price indices, analyzed projects, and recommendations. Suggesting renovation actions based on previous cases and existing data can contribute to the building experts considering aspects they would not have considered else wise, but on the other hand, it might compromise their creativity and innovation. 3.4. Generation of design alternatives At this step, different renovation options are identified. The production of design alternatives usually lies with the design team and must, therefore, involve subjective value judgments [79]. Several tools suggest renovation actions and some generate design alternatives automatically based on a set of predefined criteria (Table 6). The aim of EPIQR is assessing cost-effective energy-related improvements for the renovation of apartment buildings. Qualitative parameters are not included. In EPIQR, the deterioration state of 50 different building elements of the existing building is assessed and displayed in an active graph, in which the user easily can switch to see renovation costs, along with an active energy flowchart informing the user of the estimated energy calculations for the scenario. In that way, the individual elements can be ticked on and off depending on the priorities of the user and different levels of interventions on the elements can be decided. EPIQR suggests renovation actions based on the building diagnosis and uses local databases to estimate costs [20]. The suggestion for each building element is based on the deterioration state of the element, complaints made by the users in the performed user survey, the remaining lifespan of the element (calculated using the MEDIC module [21]), and finally information from the energy calculation module. EPIQR provides both a simple and a more detailed cost calculation module. However, e.g. indoor climate is treated as a consequence of the user survey and linked to suggesting improvements of building elements. Other tools which suggest renovation actions are e.g. BR-DSS [30], REFLEX [42], and GENE_ARCH [27]. The BR-DSS tool can

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Table 3 Sustainability objectives and criteria included in the reviewed tools. Tool or authors Gorgolewski [18] Gorgolewski [19] EPIQR [20]

MEDIC [21] MCDM-23 [22] TOBUS [23]

ORME [24]

MOGA [25] GENE_ARCH [26,27] SST tool [28]

XENIOS [29]

Social sustainability

Economic sustainability Annual energy/operational cost

Energy use (space heating, domestic hot water, Indoor Environmental Quality (IEQ) (humidity, noise, thermal comfort, air quality and ventilation, boiler replacement, space cooling, artificial lighting, safety and security, apartment utilities) lighting of shared spaces, insulation of heating distribution pipes, use of thermostatic radiator valves) Architectural quality, Indoor quality, functionality IEQ (thermal comfort, indoor air quality (humidity, pollutants, ventilation, lighting and noise)), functional obsolescence (user needs, flexibility, divisibility, maintainability, compliance with regulations) Predicted percentage of dissatisfaction, outdoor airflow rate per person, Noise level at working place

Resource use, environmental loading

Wang et al. [34]

Daylight and thermal comfort

Annual energy cost/operational cost, investment cost Costs (tender price)

Global refurbishment cost Construction cost, annual energy cost, annual maintenance cost

Energy use (heating, cooling and ventilation, heat for service hot water, lighting, equipment, electromechanical installations, water use)

Annual normalized energy use for heating, cooling and other appliances, Normalized cost of building, Annual normalized carbon gas emission and nuclear wastes emission

Occupant thermal comfort Daylight and artificial lighting, architectural Annual energy consumption (heating, cooling, aspects ventilation, illumination) Maximization of functionality (including human Minimization of environmental problems comfort and technological feasibility in the form of reliability and controllability) Environmental impact, energy demand for heating and cooling, water conservation Maximization of functionality Minimization of environmental problems

‘‘knapsack’’ model [17] BR-DSS [30] Harmfulness to health, aesthetics, maintenance properties, functionality, comfortability, sound insulation, longevity INVESTIMMO [31] Multivariant Open, based on the use of various experts' design [32] methods Pushkar et al. [33]

Wetter et al. [35] BEPAS [36]

Environmental sustainability

Energy cost Construction costs Minimization of costs

Investment cost Minimization of cost (investment cost) Cost, annual fuel economy, tentative pay-back time Investment costs and running costs

Open, based on the use of various experts' methods Life cycle environmental impact (including heating, cooling, ventilation, and artificial lighting energy needs or consumption, energy sources, embodied impacts, maintenance impacts, end of life impacts) Life cycle environmental impact (Embodied energy, energy needs or consumption for heating and cooling, reduction of exergy consumption due to pre-operation phase, reduction of exergy consumption due to operation phase) Annual energy consumption for lighting, cooling and heating Life cycle environmental impact (global warming potential, ozone layer depletion potential, acidification potential, eutrophication potential, airborne suspended particles, solid waste, photochemical smog potential, waterborne toxicities, waterborne suspended substances, water resources, fossil energy sources, metals and rocks, lumber, heating, cooling, lighting, and domestic hot water energy needs or consumption, water consumption, embodied impacts, area of green plantation, area of impermeable ground)

Juan et al. [37] Area, spatial needs, spatial flexibility, spatial relation, spatial form, and spatial size Degree of contamination, Soil fertility Zavadskas Quality of life, increase of population's income, et al. [38] increase of sales in the area, increase of employment, state of income from taxes, business outlook, difficulties in changing purpose of site, attractiveness of the countryside, population activity index Kaklauskas Comfort Technical and technological factors et al. [39] Cooling and heating loads

Open, based on the use of various experts' methods

Operational energy cost

Cost

Cost Material investments, foreign investments, building redevelopment cost

Market value, costs

(continued on next page)

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Table 3 (continued ) Tool or authors Znouda et al. [40] Martinaitis et al. [41] REFLEX [42]

Social sustainability

Environmental sustainability

Economic sustainability

Energy efficiency

Initial investment, installation, maintenance, and energy operating cost Investment cost

Annual energy savings Thermal comfort indices (winter and summer), indoor air quality, home friendliness, renovation work inconveniences Juan et al. [43] Usage (Spatial function, Plumbing, Interior Utility (Electricity Saver, Water Saver) aesthetics), IEQ, health (indoor air quality, interior finishes, electromagnetic control), safety (Structural safety, precaution equipment, personal safety), convenience (Equipment deterioration, handicapped facility, Intelligent wiring system) Verbeeck et al. Life cycle environmental impact (energy flows and [45] global warming potential) Diakaki et al. Energy consumption (space heating, cooling, [46] domestic hot water (DHW) systems, electric lighting), CO2 emissions Energy efficiency (thermal and moisture Juan et al. [47] IEQ (outdoor air introduction and exhaustion protection, HVAC and electric lighting, innovative systems, tobacco and smoke control, indoor chemical and pollutant control, occupant comfort energy technology), Water efficiency (Water performance measurement, wastewater and indoor air quality management) Sustainable site (Exterior pavement improvement, technology, water use reduction, cooling tower water treatment) heat island reduction, greenery) Material and resources (storage and collection of recyclables, sewage and garbage improvement) Environmental aspects (Site and situation, scenic/ Wang et al. Cultural aspects (historical value, artistic value, contextual value and the environmental effect, [48] conditions of integrity and/or authenticity) land use plan or zoning, regional development Architectural aspects (Physical condition of the building, architectural character and evaluation, policies, potential environmental quality of the space gain and space change, structural analysis, surroundings) technological value, materials and decorations of the building, building code) Social aspects (Compatibility of newly introduced uses with existing, public interest, social value, increasing public awareness, involvement, and support, enhancing the role of communities) Continuity aspects (Adequate protection and management system, future change feasibility, ecological and cultural sustainability) Liu et al. [49] Energy efficiency of energy systems, energy savings and emissions reductions Li et al. [50] Life cycle environmental impact (global warming, ozone exhausting, acidification, eutrophication, airborne suspended particles, solid waste, photochemical smog, waterborne toxicities, waterborne suspended substances, water depletion, fossil energy source depletion, other depletion, disability adjusted life years) Magnier et al. Thermal comfort Energy consumption [51] MAMVA, DSS- Value-based Value-based CRP [52] Crawford et al. Life cycle environmental impact of building [44] construction assemblies Total value Value-based Value-based model [53] MultiOpt [54] Thermal comfort Energy consumption, life-cycle environmental impact (global annual primary energy consumption, ventilation energy consumption, embodied CO2, CO2 emissions from global annual primary energy consumption) Tsai et al. [55] Reduce energy consumption and CO2 emission (CO2 emissions from global annual primary energy consumption, maintenance works embodied CO2) Bermejo et al. Thermal comfort [56] Expected quality of living, living costs before and Ecological footprint, primary energy need, Euro. Retro. after renovation greenhouse gas emissions and ecological scarcity Advisor [57] Medineckiene Indoor environment Energy, materials, and chemicals et al. [58] Renobuild Social interaction, teamwork and meetings, “a Life cycle environmental impact (Global warming [59] cohesive city” (variety of apartments of different potential, global warming potential payback

Investment costs, cumulated financial gain

Operational costs, initial investment cost

Economic aspects (Potential market, financial sources, subsidize, initial investment and necessary investment in future maintenance, profits from market demand, benefits of exemption)

Investment and operation costs

Value-based

Value-based Construction cost

Investment costs

Existing rent income, cost for repair or retrofit, cost for demolition and reconstruction

LCC (investment costs, reinvestment, and replacements, running management and

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Table 3 (continued ) Tool or authors

Social sustainability

Environmental sustainability

Economic sustainability

sizes, variation in rent levels, variation in forms of period, accumulated environmental impact over the whole life cycle (production, transportation, ownership, accommodation suited to special use, end of life treatment)) needs), Well-functioning everyday life, identity and experience, health and green urban environments, safety, security and openness RENO-EVALUE Value-based Value-based [60]

maintenance, energy costs, rental income and loss of rental income)

Value-based

Table 4 Methods used for weighting criteria. Name of tool

Year

Authors/developers

Weighting method

MCDM-23 ORME SST tool ‘‘knapsack’’ model BR-DSS Multivariant design

2000 2002 2003 2004 2004 2005 2006 2007 2007 2009 2010 2011 2014 2014

Balcomb et al. [22] Roulet et al. [24] Alanne et al. [28] Alanne [17] Zavadskas et al. [30] Kaklauskas et al. [32] Juan et al. [37] Zavadskas et al. [38] Kaklauskas et al. [39] Juan et al. [43] Wang et al. [48] Kanapeckiene et al. [52] Zimmermann [57] Medineckiene et al. [58]

Analytic Hierarchy Process Not specified The Grading method The Grading method Not specified Not specified Analytic Hierarchy Process Presents individual weighting method Presents individual weighting method Analytic Hierarchy Process Analytic Hierarchy Process Not specified Not specified (Value based) Analytic Hierarchy Process

OLSC

MAMVA, DSS-CRP Euro. retro. advisor

Table 5 Methods and data used for registration of the existing building. Name of tool Year Authors/ developers 2000 Jaggs and Palmer [20]

TOBUS

2002

XENIOS

2004

BR-DSS

2004

REFLEX

2007

2009 2010 Euro. Retro. Advisor

2014

Method for registration

Other data

Records of energy consumption Apartment Occupant questionnaire (experienced indoor environmental quality), Checklist, problems within the building (occupants), Checklist, energy audit (Auditor) Flourentzou Office Checklist, building structure and services (building manager et al. [23] and technical staff) Questionnaire, comfort and complaints (occupants) Checklist (auditor) Dascalaki et al. Hotel Building audit, deterioration assessment (auditor with [29] users) Zavadskas e Questionnaire (optional) Economic information (financial databases) (optional) et al. [30] General facts about the building (deterioration and obsolescence) Conceptual information (digital/numerical, textual, graphical, diagrams, graphs and drawing, etc.), photographic, sound, visual (video)) (optional) Droutsa et al. Residential EPIQR building audit (plus local and urban neighborhood [31] quality, environmental impact of buildings and building products, necessary resources for the building life cycle, upgrading and maintenance potential, the cultural perceptions, rental market nature and evolution) Pasanisi et al. Residential Description of the existing building [42] Customer wishes and constraints (expected reduction of the energy consumption, maximal budget, unwished systems and materials, a minimal number of data concerning the house: the dwelling type, age, number of floors, area, energy used for the heating and domestic hot water) Juan et al. Housing On-line basic assessment questionnaire (physical and [43] functional conditions) Juan et al. Office User survey [47] Zimmermann Residential Building type [57] apartment Building data (heated floor area, plot size, attractiveness of location, energy consumption, rents, site value, construction costs) Actual state of building Repair, retrofit or reconstruction needs

EPIQR

INVESTIMMO 2004

Building type

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Table 6 Tools which suggest renovation actions or generate design alternatives. Name of tool

Year

Authors/developers

Approach

EPIQR TOBUS GENE_ARCH

2000 2002 2002

Jaggs and Palmer [20] Flourentzou et al. [23] Caldas et al. [26,27]

SST tool BR-DSS

2003 2004

Alanne et al. [28] Zavadskas et al. [30]

Multivariant design

2005 2007 2007 2009 2010 2010 2010 2010

Kaklauskas et al. [32] Znouda et al. [40] Pasanisi et al. [42] Juan et al. [43] Diakaki et al. [46] Juan et al. [47] Liu et al. [49] Magnier et al. [51]

Suggests renovation actions Suggests renovation actions Generates building geometry or elements on fixed building geometry (facade design, window sizing, shading systems or construction materials) Formulate all workable combinations of renovation actions Provides recommendations Makes up to 100,000 renovation alternative versions Develops renovation alternatives Generates architectural solutions Generates retrofit solutions (energy and economy) Provides actions based on priority Provides solutions according to preferences Provides solutions according to preferences Design of energy system Provides solutions according to preferences

REFLEX

generate multiple renovation scenarios using the method for a multi-variant design [32], which are then checked for their capacity to meet the requirements of the specific project. The intention of the software is to select the best possible scenarios based on the initial data inputs [30]. A multi-criteria analysis of the components of the renovation project is performed, and the most efficient versions are selected. The evaluation of the alternatives is made based on conceptual and quantitative information collected at the building diagnosis. In that way, conceptual, or qualitative, information is considered; however, it is however not directly integrated into the tool. In REFLEX, renovation solutions are generated on the basis of a detailed description of an existing house. A multi-criteria analysis finds the best variants of the renovation for each element of the building, depending on the criteria for the individual element. Hereafter, possible combinations are explored using maximum budget and required improvement of energy efficiency as constraints, defined by the user. GENE_ARCH is an evolution based generative design system which uses adaption to generate architectural form. The intention of the system is to generate complete building designs, including geometry, spatial layout, construction materials, internal finishes, types and characteristics of the window and glazing systems, and even mechanical and electrical installations [27]. GENE_ARCH has been applied to problems where the geometry has been generated based on parameters set by the user and in situations where the geometry is fixed, which imitates the situation of a renovation where a building already exists, and the modifications of shape and orientation are limited. In each of the examples, the use of GENE_ARCH has been simplified, e.g. generating alternative façade solutions for an existing building, where trade-offs between architectural design intentions, natural lighting, and energy performance guide the generation of façade solutions [27]. GENE_ARCH differs from the rest of the tools subject to this review as it actively includes architectural quality as a parameter for automatic generation of design alternatives. Using an expert system for generating architectural solutions can open up the solution space, and in that way serve as a support for the architect. Also, it could substantiate an integrated design process, in which technical aspects are considered and included at an early stage and where they have the greatest impact. This idea of using algorithms for form-finding or form-making, having multiple parameters informing the design outcomes, verge on the paradigms of parametric or generative design. However, as these are mainly used as design methods within the field of architecture and as the concept of sustainable building design is broader than just architectural quality, it would be extremely complicated to encompass all aspects into just one tool or algorithm.

3.5. Estimate performance of design alternatives Simulation tools can be put to use, ranging from simple economic and energy calculations and rough estimates to complex and comprehensive simulations in order to estimate the performance of the project specific measures. Out of the reviewed tools, 84% deal with this aspect in different ways (Table 7). The tools can be divided into two groups: the ones connected to external simulation or calculation programs and the ones with an integrated simulation or calculation module. Furthermore, multiple tools use different types of genetic algorithms (GAs) for searching and optimization purposes. 28% of the tools are connected to external simulation software. Gorgolewski [18] used the BREDEM 8 model for predicting annual energy consumption of an existing flat and predicted space-heating savings in housing by using TAS software [19]. The GENE_ARCH system [27] combines a GA as a search engine with DOE2.1E building energy simulation software as the evaluation module. MCDM-23 [22] uses ENERGY-10 to estimate hour-by-hour energy performance. Liu et al. [49] use TRNYS and combine a simulationbased Artificial Neural Network with a multiobjective GA (NSGAII) for optimization. MultiOpt [80] is based on existing software and methods and also uses a GA coupled to TRNSYS, as well as economic and environmental databases. Examples of tools which have a calculation module inherent are EPIQR and TOBUS, performing a simplified energy balance calculation based on EN-832 [81], along with cooling energy calculations based on the balance point method [77]. Wetter and Polak [35] propose a simulation-precision control algorithm and present a new building energy and daylighting simulation program. 21% of the reviewed tools include a life cycle assessment (LCA), and 16% include a life cycle cost (LCC) approach. LCA is a recognized analytical method for assessing the environmental impacts of products or services from a cradle-to-cradle perspective [82,83]. An example of an LCA-based decision support tool is BEPAS, which aims to assess the environmental performance of a new or existing building, investigating aspects of building facilities, construction materials, and location [36]. Crawford et al. [44] present a comprehensive framework for assessing the life-cycle energy of building construction assemblies. LCC is a method for analyzing costs related to a product during its life cycle, including costs both related to initial investment and operation. Juan et al. [68] present a decision support system for housing condition assessment and refurbishment strategies, using genetic algorithms to analyze the trade-offs between cost and quality, where LCC is used to calculate the cost score for considered renovation actions. The multi-objective optimization model presented by Wang

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Table 7 Tools that include the aspect of performance estimation. Name of tool Year Authors/ developers

EPIQR

MEDIC MCDM-23 TOBUS

MOGA GENE_ARCH SST tool ORME XENIOS

1995 Gorgolewski [18] 1996 Gorgolewski [19] 2000 Jaggs and Palmer [20]

External simulation, calculation or analysis

Integrated simulation, calculation or analysis module

BREDEM 8 TAS (Thermal simulation)

LCC (Life Cycle Cost)

TAS (Thermal simulation)

LCC

2000 Flourentzou et al. [21] 2000 Balcomb et al. ENERGY-10 [22] 2002 Flourentzou et al. [23] 2002 Wright et al. [25] 2002 Caldas et al. DOE2.1E building energy simulation software [26,27] 2003 Alanne et al. [28] 2002 Roulet et al. [24] 2004 Dascalaki et al. [29]

BR-DSS

2004 Zavadskas Not specified et al. [30] INVESTIMMO 2004 Droutsa et al. [31] Variable 2005 Pushkar et al. EnergyPlus grouping [33] 2005 Wang et al. LCA [34] 2005 Wetter et al. [35] Multivariant 2005 Kaklauskas design et al. [32] BEPAS 2006 Zhang et al. [36] 2006 Juan et al. [37] 2007 Zavadskas et al. [38] OLSC 2007 Kaklauskas et al. [39]

2007 Znouda et al. [40]

REFLEX

2007 Martinaitis et al. [41] 2007 Pasanisi et al. EDF-R&D SimFast [42] 2009 Juan et al. [43] 2010 Crawford et al. [44] 2010 Diakaki et al. [46] 2010 Juan et al. [47] Design Advisor (Energy performance including energy consumption, life cycle energy cost, and CO2 emissions) 2010 Verbeeck et al. [45] 2010 Liu et al. [49] TRNSYS simulations

MAMVA, DSS-CRP MultiOpt

2010 Li et al. [50] 2010 Magnier et al. TRNSYS simulations [51] 2011 Kanapeckiene et al. [52] 2011 Chantrelle TRNSYS simulations et al. [54]

Search, Optimization or ranking technique(s)

Energy balance calculation Cost analysis for individual building elements Calculates remaining lifespan of building elements LCC Energy balance calculation Cost analysis for individual building elements Energy cost

GA (Genetic Algorithm) GA

ELECTRE family algorithms (ELECTRE III and VI) Energy balance calculation Installation cost payback period Not specified

Not specified

LCC LCA (Life Cycle Assessment)

GA

LCC

GA

Building energy and daylighting Simulation-precision control simulation algorithm Multivariant design and multiple criteria analysis LCA Cost GA, case-based reasoning Fuzzy method of multiple-criteria complex proportional evaluation Determining the utility degree and market value of alternatives, Method of multiple criteria complex proportional assessment (COPRAS) GA Thermal evaluation (CHEOPS), Costs (initial investment, installation, maintenance, and energy operating cost) Costs, energy efficiency

LCC GA LCA for building construction assemblies Costs, energy savings

LCA, LCI (life cycle inventory) LCA

GA and zero-one goal programming, A* search algorithm GA GA (NSGA-II), Artificial Neural Network

LCA GA (NSGA-II), Artificial Neural Network Market value assessment GA (NSGA-II) (continued on next page)

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Table 7 (continued ) Name of tool Year Authors/ developers

Renobuild

External simulation, calculation or analysis

Integrated simulation, calculation or analysis module

2011 Tsai et al. [55] 2012 Bermejo et al. [56] €rnell et al. 2014 Mjo [59]

Search, Optimization or ranking technique(s)

LCA Thermal comfort simulation LCA, LCC, Social Life Cycle Analysis

et al. [34], and the method for evaluating different renovation al€ rnell et al. [59], include both LCA and ternatives presented by Mjo LCC. Including LCA and LCC calculation modules in decision support tools is an interesting approach regarding environmental and economic sustainability aspects. However, as LCA primarily is used for assessment or certification, it might be included in a simplified way to be used actively in the design process. Genetic algorithms were used in several tools for searching and optimization purposes. The concept of genetic algorithms was created by John Holland [84] and takes its origin in Darwin's theory of evolution, using stochastic search techniques based on the mechanism of natural selection and natural genetics [85]. Potential solutions to a problem are represented as a population of chromosomes, and each chromosome represents a possible solution. The chromosomes evolve through successive generations; offspring chromosomes are created by merging two parent chromosomes using a random crossover mutation. During each generation, the performances of the chromosomes are evaluated to the fitness functions, and fitter chromosomes have higher chances of survival. After several generations, chromosomes may be close to identical, and the final chromosomes hopefully represent the optimal or near-optimal solution to a problem [85]. Wright et al. [25] use a multi-objective GA for investigating the pay-off between an HVAC system energy cost and occupant thermal comfort to inform the building design process. Juan et al. [37] use a hybrid approach combining case-based reasoning and GA. Znouda et al. [40] propose an optimization algorithm that couples GAs with a simplified tool for building thermal evaluation to minimize energy consumption in Mediterranean buildings. They also propose using GAs for the purpose of economic optimization. 3.6. Evaluation of design alternatives At this stage, different renovation scenarios can be assessed quantitatively and qualitatively, based on the criteria for the particular project. If the goal is to certify the building, a building sustainability assessment is performed. A majority of the tools explicitly include the step of evaluation of renovation alternatives where the potential alternatives are evaluated against the project objectives. Evaluation is usually done continuously throughout the design process, e.g. evaluation of simulation results, calculations or aesthetic quality. Therefore, it can be argued that the aspect of evaluation is implicitly inherent in all the tools included in this

review as the results provided by the tools will always be interpreted and evaluated by one or more building experts. However, the tools represented in Table 8 include the aspect of evaluating design alternatives by providing explicit guidelines for the evaluation procedure. Common is the fact that final choices are made based on an individual's or group's knowledge and experience. Having stated the project objectives clearly at the beginning entails a more efficient evaluation. Furthermore, if this is done in a systematic way, the objectives can serve as a design tool for evaluation throughout the design process. €rnell et al. [59], provides a The methodology presented by Mjo framework for evaluation of renovation alternatives based on economic, environmental and social sustainability aspects, with special emphasis on integrating social sustainability aspects into building renovation [86]. In similarity with RENO-EVALUE [60], the €rnell et al. [59] provides a evaluation framework presented by Mjo visual representation of the results to make it easier for the decision-maker to interpret the evaluation results. High-quality, sustainable design solutions include expert knowledge from multiple different professional fields. Therefore, it is important to have in mind that one tool should not strive to take over the role of building experts and advisors, or the tools they use in their particular field, but merely serve as an aid to managing the complexity of the decisions throughout the design process. 4. Perspectives on future development Making tools freely available can ensure equal access to the necessary knowledge and contribute to a more transparent work process. This has been intended for several of the tools reviewed, but only a few of them were available online at the time of this review. This can be because the projects in which the tools have been developed have closed down, the website has been closed, or maybe for commercial reasons. Furthermore, comprehensive tools that depend on up-to-date databases that follow the present regulations or prices to perform calculations need to be updated continuously in order to be useful. This substantiates the need for developing simplified tools that are flexible enough to meet the changing demands of sustainable building design. One way to meet these demands could be connecting decision support tools to existing databases and systems. Sustainability assessment methods such as e.g. BREEAM, LEED,

Table 8 Tools that provide explicit guidelines for evaluation of design alternatives. Name of tool

Year Authors/ developers

Evaluation approach

‘‘knapsack’’ model

2004 Alanne [17]

A list of questions is provided to the evaluator.

Total Value Model Renobuild

2010 Wang et al. [48] Propose basic evaluation questions regarding reuse of historic buildings. 2011 Plan C [53] Provides suggestions for questions, activities, and tools to use in the evaluation of potential solutions.

€ rnell et al. 2014 Mjo Renovation alternatives are evaluated from environmental, economic and social perspectives. [59] RENO-EVALUE 2015 Jensen et al. [60] The finished design is evaluated based on a simple spider-web diagram, reflecting the expectations and success criteria of the involved stakeholders.

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Fig. 4. Suggestion of modules, their interrelations and related actions for future decision support tools for sustainable renovation of one or multiple buildings.

CASBEE, and DGNB have been adapted to renovation purposes, enabling certification of renovated buildings. Integrating the principles from the local sustainability assessment methods, such as DGNB-DK in Denmark, in a simplified way, could support the decision-making process in the pre-design stage, and in that way, the criteria could provide a direction for the building diagnosis. Following the ideas of sustainability assessment methods when developing decision support tools for renovation could be a

relevant option as this would strengthen the common aims of sustainability in the building industry locally. On the other side, developing tools independently of existing assessment methods might induce more innovative solutions. Cooperation and communication between stakeholders in construction projects is a subject out of scope for this review, but culture and traditions naturally have a significant impact on how the involved actors communicate. Introducing new tools can be

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seen as a burden since there are already a great variety of tools available and learning new systems takes time and effort. One suggestion could be to combine existing concepts in a structured way, which can then serve as a support for decision makers and not as a burden. 4.1. Renovation of multiple buildings Dealing with the renovation of multiple buildings is a relevant matter, e.g. for municipalities and housing associations. Here the first step in the decision process, besides decisions made on a political level, can be which buildings to renovate and in which order, or which renovation actions to prioritize within the building portfolio, e.g. update specific functionalities within one specific building typology. Of the reviewed tools, EPIQR [20], TOBUS [75], INVESTIMMO [31] and MEDIC [21] are specifically aimed towards multiple buildings. They provide a model for performing a diagnosis of the existing buildings that seeks to be as efficient as possible time-wise and, at the same time, provide the necessary information concerning degradation of building elements and occupant satisfaction. However, one downside to the EPIQR software is that it depends on local databases, which are not accessible in all local contexts and, therefore, only some aspects of the method can be used in that case. The aspect of setting objectives within a larger building portfolio can be approached in the same way as with a single building. Here, however, it is relevant to include that a model could be generic to support in prioritizing actions within different building typologies, or it could be designed specifically for one building type, e.g. school buildings. Choosing between existing buildings demands that the values and objectives of the decision makers are clearly defined, or there is a chance that the evaluation will be vague and unsystematic. For this purpose, the methods for goal setting presented in this review can be useful. One tool which is interesting in this regard is the Office Building Rating Methodology (ORME) [24], which aims to rate and rank office buildings and renovation scenarios of the same building according to an extended list of pre-defined parameters, using ELECTRE algorithms. This approach could be adapted to fit the necessary objectives in the individual case, whether criteria are based on existing assessment methods or case-specific criteria defined by the decision makers. 4.2. Roadmap for future development Based on the findings in the review, the authors suggest that the following modules are considered when developing decision support tools for sustainable renovation of one or multiple buildings:

 A Goal Setting Module containing the aspects of setting sustainability goals, choosing and weighting criteria. The criteria can be adapted from existing sustainability assessment methods or based on project-specific criteria.  A Registration Module providing a method and a platform for registration of the existing building(s). Existing databases are used to make the registration less time-consuming and ensure a sufficient level of information.  If dealing with multiple buildings, it is suggested to include a Ranking Module where the buildings are ranked in relation to their renovation need. (It should be possible to focus on individual elements so as to get a prioritized list of renovation actions.)  A Recommendation Module providing recommendations for renovation actions based on the sustainability criteria and registration information defined in the Goal Setting Module and the Registration Module.  An Evaluation Module providing the option of evaluating the design during the design process or assess the finished design in relation to the sustainability goals. Fig. 4 shows the modules with their interrelations and related actions. The suggested modules are specifically focused on renovation of existing buildings, but some elements could serve as inspiration in the development of decision support tools for designing new buildings as well, e.g. the Goal Setting and Suggestion Modules. 5. Conclusion The aim of this paper was to provide a state-of-the-art overview of the development of decision support tools applicable in the predesign and design phase of renovation projects in order to identify areas for future research. Six areas where decision support tools can substantiate the renovation process have been identified. The tools have been categorized and discussed in relation to these areas. An overview of the percentage of tools in each category is shown in Fig. 5. This review has shown that there has been a continuous development of decision support tools for renovation since the mid-1990s, varying in methodological approach, complexity, and sustainability objectives. The criteria encompassed in the 43 reviewed tools have been divided into the categories of social, environmental, and economic quality, showing that 40% of the reviewed tools include criteria from all three categories. 81% of the tools included environmental criteria, 72% included economic criteria, and 63% included social criteria.

Fig. 5. Percentage of tools in each category.

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The aspect of Goal Setting is included in 21% of the tools. Even though it is essential to set the appropriate sustainability goals, only 5% of the reviewed tools provide a model for determining objectives and choosing criteria for the project. Both RENO-EVALUE and the Total Value Model provide a checklist that seeks to entail dialogue among the stakeholders in order to establish a common ground and point of departure for the project. The predefined criteria for RENO-EVALUE and the objectives in the Total Value Model seek a broad and holistic approach to sustainability and provide checklists to ensure that all aspects are included at an early stage. The development of methods and guidelines for setting goals and choosing criteria for sustainable renovation is recommended as an area for future research. The most used weighting method within this review is AHP, in which criteria are compared pair-wise, subjectively determining their relative importance. AHP has been widely used in the building industry but has been criticized by e.g. Arroyo [70]. The authors suggest comparing weighting methods for use in the pre-design phase of sustainable renovation projects as a relevant subject for future research. 21% of the tools provide guidelines and specific methods for the aspect of registration and collecting data about the existing building and its deterioration state. The methods and the type and amount of data to be collected do not differ much, and often the time used for registration and data collection is sought minimized while still being sufficient. Looking towards existing methods for performing the building diagnosis is relevant in the development of new decision support tools for building renovation. Furthermore, existing methods such as the Post Occupancy Evaluation (POE) [87], the evaluation tool Design Quality Indicator (DQI) [88] or the Surveys of Architectural Value in the Environment method (SAVE) [89] could be integrated into future decision support tools to assess the current state of one or more buildings, depending on the objectives of the individual renovation project, function, and building typology. The approach to generating design alternatives vary among the reviewed tools; some suggest renovation actions based on the state of the current building and its elements while others compute design solutions. Both approaches could be relevant for investigation to a further extent in future research, and integrating generative design methods in building renovation indeed has potential. However, this aspect might be slightly out of scope in the development of decision support tools for renovation and might belong in the architects' toolbox. The tools supporting performance estimation are heavily represented by 84%, possibly because these are the areas where IT solutions can support the design process regarding simulation and calculation. Computers can provide calculation power and allow continuous evaluation of design alternatives through simulations. GAs have been utilized by multiple of the reviewed tools for optimization purposes, imitating the process of natural selection. Using GAs provide a method for searching the solution space and evaluate the fitness of solution in relation to the given parameters. The aspect of evaluation is explicitly represented in 12% of the tools. It is difficult to isolate the evaluation step as this is implicitly inherent throughout the process, e.g. in the evaluation of simulation results or internal design iterations. Furthermore, it is a challenge to automate the evaluation process and it will always be dependent on human evaluation. The authors suggest the following areas for future research in relation to the development of decision support tools for sustainable building renovation:  The aspect of setting sustainability goals and choosing criteria should be emphasized in the development of future decision support tools.

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 Guidelines or models for building diagnosis should be provided, systemizing the registration and data collected with regard to the existing building. Existing methods could be adapted and integrated into new tools or methods.  Tools should be flexible with regard to choosing and/or weighting criteria. In that way, using criteria and weights from sustainability assessment methods is an option.  The choice of AHP as a preferred weighting method should be challenged in comparison to other relevant weighting methods, testing their applicability in the pre-design phase of renovation projects.  It should be considered to make tools freely available online as this could improve knowledge-sharing and make the process more transparent for the involved stakeholders.  New tools could be connected to existing databases, facility management systems, simulation tools, calculation tools and BIM models to the extent it is advantageous.  Instead of focusing on developing single, comprehensive tools, combining existing methods and tools could be beneficial.  New tools aimed towards helping professional building owners manage renovation decisions in larger building portfolios is of high relevance and should be considered. References [1] A.R. Pearce, Y.H. Ahn, HanmiGlobal, Sustainable Buildings and Infrastructure. Routledge, Taylor& Francis Group, 2012. [2] European Parliament, Directive 2002/91/EC of the European parliament and of the council of 16 December 2002 on the energy performance of buildings, Off. J. Eur. Union (2002) 65e71, http://dx.doi.org/10.1039/ap9842100196. [3] European Commission, Europe 2020 e Europe's Growth Strategy, 2010, http:// dx.doi.org/10.1016/j.resconrec.2010.03.010. [4] R. Ramírez-Villegas, O. Eriksson, T. Olofsson, Assessment of renovation measures for a dwelling area - impacts on energy efficiency and building certification, Build. Environ. 97 (2016) 26e33, http://dx.doi.org/10.1016/ j.buildenv.2015.12.012. [5] Energistyrelsen, Denmark's National Energy Efficiency Action Plan (NEEAP), 2014. Denmark. [6] The Danish Government, Strategi for Energirenovering Af Bygninger, 2014. [7] G.K.C. Ding, Sustainable constructionethe role of environmental assessment tools, J. Environ. Manag. 86 (2008) 451e464, http://dx.doi.org/10.1016/ j.jenvman.2006.12.025. [8] J. Markelj, M.K. Kuzman, M. Zbasnik-Senega cnik, A review of building sustainability, Archit. Res. (2013) 22e31. [9] J. Zuo, Z.-Y. Zhao, Green building researchecurrent status and future agenda: a review, Renew. Sustain. Energy Rev. 30 (2014) 271e281, http://dx.doi.org/ 10.1016/j.rser.2013.10.021. [10] S.H. Alyami, Y. Rezgui, Sustainable building assessment tool development approach, Sustain. Cities Soc. 5 (2012) 52e62, http://dx.doi.org/10.1016/ j.scs.2012.05.004. €rnell, P. Meiling, Unveiling the process of [11] L. Thuvander, P. Femenías, K. Mjo sustainable renovation, Sustainability 4 (2012) 1188e1213, http://dx.doi.org/ 10.3390/su4061188. [12] S. Mancik, J. Ruzicka, Assessment Tool for Renovations ReSBToolCZ. CESB 2013 PRAGUE e Central Europe towards Sustainable Building 2013: Sustainable Building and Refurbishment for Next Generations, Czech Technical University in Prague, 2013, pp. 713e716. [13] S.D. Pohekar, M. Ramachandran, Application of multi-criteria decision making to sustainable energy planning - a review, Renew. Sustain. Energy Rev. 8 (2004) 365e381, http://dx.doi.org/10.1016/j.rser.2003.12.007. [14] D. Kolokotsa, C. Diakaki, E. Grigoroudis, G. Stavrakakis, K. Kalaitzakis, Decision support methodologies on the energy efficiency and energy management in buildings, Adv. Build. Energy Res. 3 (2009) 121e146, http://dx.doi.org/ 10.3763/aber.2009.0305. [15] J. Ferreira, M.D. Pinheiro, Brito J de. Refurbishment decision support tools reviewdEnergy and life cycle as key aspects to sustainable refurbishment projects, Energy Policy 62 (2013) 1453e1460, http://dx.doi.org/10.1016/ j.enpol.2013.06.082. [16] M.H. Bazerman, Judgment in Managerial Decision Making, 1998. New York. [17] K. Alanne, Selection of renovation actions using multi-criteria “knapsack” model, Autom. Constr. 13 (2004) 377e391, http://dx.doi.org/10.1016/ j.autcon.2003.12.004. [18] M. Gorgolewski, Optimising renovation strategies for energy conservation in housing, Build. Environ. 30 (1995) 583e589, http://dx.doi.org/10.1016/03601323(95)00011-T. [19] M. Gorgolewski, P.C. Grindley, S.D. Probert, Energy-efficient renovation of high-rise housing, Appl. Energy 53 (1996) 365e382, http://dx.doi.org/

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