In English

Renovating with a greenhouse and Phase Change Material - Assessing sustainability implications for million housing renovation

Renovera med växthus och fasbytande material - Utvärdering av påverkan på hållbarheten för ett miljonprogramshus

Oskar Mangold ; PETER SELBERG
Göteborg : Chalmers tekniska högskola, 2015. Examensarbete - Institutionen för bygg- och miljöteknik, Chalmers tekniska högskola; 2015:8, 2015.
[Examensarbete på avancerad nivå]

The buildings produced during the million housing program 1964-1975 in Sweden are facing a dire renovation need. A method of both lowering energy consumption and letting tenants stay during the process is adding a building integrated greenhouse to the façade. This produces a warmer micro climate and reduces the temperature difference between the inside and outside of the building exterior wall. The greenhouse can also be used for social interaction. By the use of phase change materials as thermal energy storage the large temperature intervals in the greenhouse could be mitigated. The greenhouse building addition was investigated as an alternate refurbishment strategy of Brogården buildings in Alingsås. These houses have gone through extensive refurbishment and have reached passive house standard. The project has been thoroughly documented which is why it was found to be a suitable object to study. The greenhouse building addition was compared to one of the buildings before and after renovation as reference cases. The greenhouse suggestion was analyzed within the three spheres of sustainability- ecology, economy and society - in relation to the reference cases. The ecologic sphere was assessed by measuring the energy flow over the wall with the greenhouse. To achieve this, all cases were modelled in COMSOL Multiphysics® where influencing physics phenomena were implemented and the use of PCM analyzed. The economic sphere was assessed by calculating the payback period for the retrofit investments. For the assessment of the social sphere it was chosen to create a new assessment tool, specifically for refurbishment of multi-residential housing buildings that would enable a quick but holistic assessment. Relevant indicators from several building certification systems were collated into a new tool aimed at investigating social sustainability in only the physical building. The certification systems were BREEAM, DGNB, LEED and Miljöbyggnad. The tool was brought to a meeting between experts assessing the social sustainability for the two alternating refurbishment strategies. It was found that the greenhouse suggestion is not a sufficient stand-alone renovation in the scenario investigated but could prove to be a reasonable investment for a building with a higher initial performance, or as a part of a renovation package. The greenhouse has an apparent effect on reducing the energy flows of the exterior wall but the addition of PCMs as heat storage has less effect than assumed. The building alterations are polarized and challenging to compare in the social and economic spheres. The social sustainability assessment tool was found to rather assess the preconditions for social sustainability rather than the actual social sustainability. Suggestions for further investigation for the ecological analysis are to extend the system boundaries to include a whole building or introduce an active heat transport system. Furthermore improvements in the economic sphere could be to investigate the effects of enveloping the entire building or all façades in a greenhouse structure. To go further with the social sustainability assessment tool it is necessary to include the process and the neighborhood scale in the assessment. It is also important to further investigate how the indicators should be weighted to value them correctly.

Nyckelord: greenhouse, phase change material, PCM, social sustainability, building certification

Publikationen registrerades 2015-12-11. Den ändrades senast 2015-12-11

CPL ID: 228055

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