Towards development of a label for Zero Emission Buildings : A Tool to evaluate potential Zero Emission Buildings

There are many concepts and labels developed with the aim to promote sustainable building. However, most of these address mainly energy aspects and do not consider the entire environmental impact of a building construction. In contrast, the concept of Zero Emission Buildings (ZEB) integrates energy and material (biomass, water) flows, resulting in buildings, which do not produce harmful emissions and on the contrary produce energy, water and resources. It envisions maximum decentralization of a building implying closed resource cycles and hence no environmental impact during its operational use. However, the concept of ZEB lacks a general framework under which potential buildings can be easily assessed. Consequently, the ZEB Assessment Tool was developed in order to easily evaluate potential ZEBs regarding their environmental performance. The ZEB Assessment Tool was developed by considering specific decision parameters and appointing an appropriate characteristic to them. These decision parameters were (i) Pre-Assessment, (ii) System boundary, (iii) Quantification of environmental impact, (iv) Database, (v) Quantification of qualitative aspects, and (vi) Calculation of target value. The evaluation of several case studies from Switzerland with the ZEB Assessment Method showed that the tool is well adapted to the requirements of OPEN ACCESS the ZEB Concept. Firstly, it requires a small amount of input data, which enables a simple primary assessment of a specific building. Secondly, it has the advantage that it evaluates a wide range of factors regarding the building’s environmental performance. These are energy, water, biomass and a set of qualitative aspects. Furthermore, it takes into account various environmental impacts and can be applied for buildings with different type of use and in different countries of location.

evaluates whether the building addresses sufficiently the three sectors Water, Energy and Biomass. For each sector a list of so-called "eligible technologies", which target efficient use of resources and energy, was compiled (Table 2). A building received a "fulfilled" for one sector if it implemented at least two of the eligible processes/ technologies of the corresponding sector. As a next requirement of the Pre-Assessment, the building had to fulfil at least two of the named sectors. If a building passed the Pre-Assessment it was further investigated with the ZEB Assessment Tool in order to quantify and benchmark the environmental performance. The Pre-Assessment ensures the integrity of the concept up to a certain level. For instance, if a building solely implemented water saving devices, it would be inappropriate to state that the building addresses appropriately the aspect of water within the ZEB concept.

Development of ZEB Assessment Tool
Quan=fica=on of qualita=ve aspects Considera=ons: • How can qualita=ve aspects be assessed in a quan=ta=ve way?
• Which criteria should be considered?
• How can sensible benchmarks be established?

Development of ZEB Assessment Tool
Quan=fica=on of qualita=ve aspects: Addi<onal UBP • Set of criteria • Alloca=on of grade: «Fully applies» «Par=ally applies» «Does not apply»

Development of ZEB Assessment Tool
Calcula=on of target value • How can considera=on be given to different building purposes and corresponding varia=on of resource consump=on? • How should the target value be calculated and expressed?

Development of ZEB Assessment Tool
Classifica=on & Benchmark and would have achieved less than 80% degree of achievement. Several such buildings obtained typically values around 100'000 Rating Points for zero degree of achievement. So the 100'000 value was taken as starting value. For the ZEB Assessment Tool, the energy consumption indicator of Minergie was converted into a general consumption index, which is proportionally in line with the energy consumption indicator of Minergie. The chosen classification corresponds to the classification of Minergie (2013). Minergie calculates for every building a weighted energy consumption indicator in matters of end energy. The indicator is expressed in kWh/m 2 and is a crucial benchmark for the Minergie label. The energy consumption indicator varies for the different types of buildings. Subsequently, the benchmark for each building type was calculated from the consumption index where Index 1 corresponds to 100'000 Rating Points. This benchmark value therefore corresponds to zero degree of achievement. The classifications of building types, the Minergie energy consumption indicators and the benchmarks for ZEBs are listed in Table 7.

Development of ZEB Assessment Tool
Calcula=on of degree of achievement Min. 80% degree of achievement to achieve the "ZEB Label" pressed in kWh/m and is a crucial benchmark for the Minergie label. The energy consumption indicator varies for the different types of buildings. For the ZEB Assessment Tool, the energy consumption indicator of Minergie was converted into a general consumption index, which is proportionally in line with the energy consumption indicator of Minergie. Subsequently, the benchmark for each building type was calculated from the consumption index where Index 1 corresponds to 100'000 UBP. This benchmark value corresponds to zero degree of achievement. The classifications of building types, the Minergie energy consumption indicators and the benchmarks for ZEBs are listed in Table 5.
The achieved number of UBP for the assessed object was calculated as follows: Subsequently, the degree of achievement was calculated: !"#$""!!"!!"ℎ!"#"$"%&! % = !100 − 100 * !"ℎ!"#"$!!!" !"#$ℎ!"#$ If a building achieved at least 80% degree of achievement, it was granted the «Zero Emission Building Label». To set this benchmark was a compromise with the actual objective of ZEB, which envisions zero environmental impact thus zero UBP. However, if this goal was applied, presumably no building would have reached the ZEB Label. The benchmark of 80% allowed for some envi-ApplicaIon ZEB Assessment Tool -Input data 14

ZEB Assessment Tool
The required input parameters for the assessment of a potential Zero Emission Building by using the ZEB Assessment Tool are listed in Table 8.   Figure 4 shows the assessment of the three sectors Energy, Water and Biomass. The user has to select certain values from a box and fill in the required values for the resource and energy flows. Figure 5 illustrates the evaluation of qualitative aspects. The user has to select in how far the correspondent criterion applies. Figure 6 shows the output data of the tool and in how far the assessed building complies with the ZEB concept. The graphics illustrate in how far the parts of the assessment are responsible for the output in order to indicate the potential for further improvement of the building.

Application of ZEB-Tool on Case Studies from Switzerland and South Korea
The ZEB Assessment Method was used to evaluate potential ZEBs in Switzerland and Korea.