Level up in a green building grading system in new construction of student housing
Abstract: The building and construction sector accounts for a significant proportion of carbon dioxide emissions in Sweden, a total of 12.2 million tons of carbon dioxide equivalents, which corresponds to approximately 19 % of the total emissions of greenhouse gas in Sweden. As a response to the fact that construction has a major impact, different environmental certification systems have emerged for buildings. One certification system is the Swedish certification system “Miljöbyggnad”, which includes sustainability issues through the whole construction process. The building can achieve three grades in Miljöbyggnad: bronze; which corresponds to the level in legislations, silver; which is the most common certification grade, and gold; that corresponds to the highest grade, thus requiring the most effort. The grade is given according to how the building performs in different assessment areas, called indicators. For new construction, the system consists of 15 different indicators within three areas: energy, indoor environment and materials. The indicators are connected to both ecological and social sustainability. The indicators connected to ecological sustainability are considered to either minimize hazardous substances, increase the amount of renewable energy or decrease the use of energy, thus a reduction in climate impact. Social sustainability is connected to how the tenant’s wellbeing is impacted by the building. The meaning of wellbeing is, in this case, health and comfort. In this master thesis the theoretical possibility of raising the Miljöbyggnad grade from silver to gold has been studied for the construction of new student housing. Stockholms studentbostäder´s new construction of four houses at Lappkärrsberget has been the study case. Stockholm’s student housing, “Stockholms studentbostäder”, is the largest actor of student housing in Sweden, with approximately 8000 housings. Stockholms studentbostäder is currently in the middle of the process that within the next ten years build 2000 new student housings. A major expansion with 800 housings will be built in their largest housing area, Lappkärrsberget. In the first building phase, the new construction of four houses is carried out, with the buildings having 10 to 13 floors which include 297 housings, mainly one room apartments and some two room apartments. The houses are built for the Miljöbyggnad grade silver according to the manual in version 2.2. After version 2.2, later versions, as version 3.0 have been launched. The main focus has been to identify what theoretical actions are required to raise the grade to gold, and to what cost. Four main questions have been studied:Is it possible to reach the grade gold for the four new buildings in Lappkärrsberget?What would it mean for the buildings, in terms of costs and actions, to raise the grade from silver to gold in version 2.2?How high grade is possible to reach for the indicator energy types, if the tenants have their own electricity agreements in the current version of Miljöbyggnad 2.2, and the later version 3.0? What general differences would it make to build in a later version 3.0, instead of 2.2? The method used has been to study the current status and then together with the manual for Miljöbyggnad make a comparison to achieve the grade gold in a specific gold scenario formulated together with Stockholms studentbostäder. In the next step, actors from the building industry both internal from Stockholms studentbostäder, external at other companies together with suppliers, were asked about what actions were needed to achieve gold and to what cost.For the first question, if it is theoretically possible to build with Miljöbyggnad gold for the new housing in Lappkärrsberget, it was concluded that it would not be possible to achieve gold due to the limited opportunities to optimize the properties of the windows with the current building performance. Therefore, it is recommended to decide what grades off the indicators to aim for and in an early stage develop the construction design and make the construction planning after the indicator grades. To achieve high grades, it is especially important to optimize the windows, in line with the requirements for the indicators. Another uncertain factor concerns how the students would respond in a survey which requires an approved result to reach a gold grade. Although it is not possible to reach gold as a building grade, it was noted that several of the indicators were close to gold and it would not be hard to raise these grades to gold to improve the overall performance of the buildings. In the second question, the cost was calculated when raising the grade from silver to gold. For this it was assumed that the windows and surveys did reach the desirable grade, and in that case the cost would increase between 0,4 % and 1,3 % of the contract budget of the project. The probable value would be somewhere in between, estimated to 0,6 %, which is a low increase in cost. In the third question, it was investigated what grade would be possible to achieve for the indicator energy types if the tenants are required to manage their own electricity agreement, in both version 2.2 and version 3.0. It was concluded that the district heating was required to change, to make an impact on the grade. Stockholm Exergi is the supplier of the district heating for the houses in Lappkärrsberget. Thus, Stockholm Exergi´s three alternatives have been studied, which differs in district heating composition and impact on the environment. The alternatives were studied for different years, due to the fact that district heating changes composition for each year. The preliminary certification of the grade in Lappkärrsberget was made with district heating data from 2016 and no matter what district heating alternative was used from 2016, the highest reachable grade is bronze in version 2.2. In version 3.0, the household electricity, meaning the tenant´s apartment electricity, is optional to use for the calculation of the grade. When calculating the grade without household electricity, with the same data as the preliminary certification, from 2016, the grade was raised to silver. With the alternatives of the district heating that were available year 2020 from Stockholm Exergi it would be possible to reach grade gold with the most environmentally friendly alternative, in version 2.2 and silver would be the highest grade in version 3.0. In the last question, version 2.2 and 3.0 were compared and some differences were noted. For example, the indicator nitrogen dioxide was removed in version 3.0 and the indicator climate impact of the foundation of the building and the building frame was added. The requirements have been updated in version 3.0. For example, the indicator percentage of energy types has a requirement that at least 5 % of the energy needs to be locally produced and renewable to reach gold level, for example with solar panels. The requirements for surveys have also been reduced in version 3.0, to fewer indicators in need of surveys and there is also an alternative to verify the grades by using measurements instead of surveys.
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