Energiuppföljning och brukarbeteende i samband med miljöcertifiering av byggnader

Sammanfattning: Environmental certification is a method to assess and rate buildings according to how environmentally sustainable they are. The four most common environmental certification systems on the Swedish market are Miljöbyggnad, GreenBuilding, BREEAM SE and LEED. Energy calculation of the building is one of many requirements to achieve certification from these systems. The calculation must fulfill the requirements defined in Boverkets byggregler (BBR) of a building's energy performance, except for LEED that requires that the energy calculation has to be structured according to a model described by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE). Miljöbyggnad and GreenBuilding require follow up of the buildings’ energy use, which BREEAM SE and LEED do not require. The purpose of this report is to examine possible improvements for monitoring of energy use in future environmental certification projects. The aim is also to examine which types of user-related changes that have been performed in earlier projects. The report also examines what needs to be done to advance the energy calculation in future projects. A comparison between the measured values to the stated calculations was carried out for 21 buildings. Only three calculations were within a range of ± 10 percent when compared to the measured energy use. Of the buildings with reliable statistical data a clear majority of the calculations underestimates the energy performance of the building. There are clear differences in the construction of the energy calculation depending on if it is based on the definition in BBR or in ASHRAE. The method of calculation for LEED is based on ASHRAE, and it shows significant differences between the actual building and the building's energy calculation. Those differences make the calculation unsuitable for following-up on the building energy performance. There are two major differences in the LEED methodology that for some buildings contribute to an unreliable energy calculation. Firstly, piping losses for hot and chilled water in the building installations are neglected in the calculation. Secondly, all spaces used by people, including zones only used limited periods, must be simulated with both heating- and cooling systems, even when no such system is installed in the building. The influence of the differences in follow-up requirements in the different environmental certification systems was investigated by a comparison of the differences between the calculated and measured energy performance between the buildings certified with different environmental certification systems. There seems to be no connection between different requirements on follow-up of the buildings’ energy use and how the difference between the buildings calculated and measured energy performance varies. This is based on the fact that out of the buildings who are certified with a system that require follow-up there are not more calculations that fall within the ± 10 percent margin compared to the buildings that are certified in systems without follow-up requirements. A survey with responses from 21 property owners were conducted. The majority of them said that current strategies for energy metering in environmental certification system are not sufficient for following-up on energy use. Among the property owners who felt that the current measurement strategies not are sufficient, the general perception was that it is not enough adapted for their business. Increased requirements for energy measurement in environmental certification systems, especially in the GreenBuilding, BREEAM SE, LEED and Svanen, would lead to better opportunities for following-up on the buildings’ energy use. This should be combined with a plan for measurement and requisite of following-up of the buildings’ energy use to ensure that the measurements are done correctly and that the requirements are fulfilled. Adaption of building user input data for calculations do not appear to be common in projects. There are no indications that there are some specific parameters that are corrected more often than others. Adaption of input data seem to be inhibited by the acceptance within the industry of using Sveby as a source for input data. This may result in less precise calculations, but it improves the opportunities for accurate comparison between different buildings hence the user of the building will have a less crucial role in the result. By a literature study it was shown that by performing the energy calculation earlier in the projects the calculation can be used to improve the building before the design parameters are determined. This may induce that the building will be better in an energy performance perspective. However, by performing the energy calculation in an earlier stage the accuracy of reliable input data will be decreased, thus lowering the precision of the calculation. If calculations instead were performed in a more ongoing methodology were the calculation is updated continuously when parameters are changed could the advantages from both the ordinary way and the early stage calculation be utilized. In this methodology the calculation could combine high accuracy in the result and still be used for compiling material for decision-making. To make this possible, the projects need to allocate resources for this methodology.