Research Contribution 2014

Research Contribution 2014
Original floor plan level 1
  • Original model (Dokka et al., 2013)


This study is a continuation on the research done by the Research Centre on Zero emission Buildings (ZEB) regarding the ZEB residential model and focuses on embodied emissions and how they can be reduced. The main aim of this research is to investigate in how to create a standard of ZEB houses that does not only have a high performance (ZEB-O or ZEB-OM level), but also is attractive to the public and can add to the built environment.

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Different variations to the original design were proposed and evaluated in terms of impacts on material emissions. The first approach focuses on the layout and footprint of the building, where a reduction is established of 25% in heated floor area. The second approach looks at the shape and materials of the building, in particularly the shape and materials of the roof. The two options are to replace the original roof with a tilted roof with building integrated photovoltaic panels (BIPV) and to replace the original roof with a green roof.

From the results of the two options of the first approach, it can be concluded that these variations will not reach a ZEB-OM level, but they still reach the ZEB-O level. The emissions per m2 heated floor area are slightly lower than for the original model, but the total reduction is linearly connected to the reduction of heated floor area. Since the proposed floor plans are more functional and result in lower total emissions, it makes these options more desirable solutions as a typical ZEB single-family house.

The changes in roof that were proposed have both positive and negative aspects. For the BIPV roof, the emissions were significantly higher regarding the category ‘outer roof’ and thus also in the total balance. The tilted roof creates extra height, which allows for a larger area of PV panels, and a third floor to be added to the building. This increases the floor area and therefore decreases the emissions in kg CO2eq/m2 to the same value as the emissions for the original roof. This is still not sufficient to reach a ZEB-OM level. The emissions for the green roof resulted to be lower for the category ‘outer roof’ even though there was an increase of 26% of embodied emissions from the roof materials. The green roof also reduces the emissions as a result of direct energy consumption by 4,5%. Despite this, the building cannot reach a ZEB-O level, because there is no on-site production.

From this study it can be concluded that for the ZEB residential model, the embodied emissions should be decreased, while the on-site production is increased in order to reach a ZEB-OM level.