Climate impact from HVAC systems in the production and construction phase: A case study of two university buildings in Sweden

Abstract

As of today, the magnitude of the climate impact of the HVAC systems is currently uncertain as few detailed studies have been made on the subject. This study therefore intends to increase the knowledge regarding the climate impact of HVAC systems by calculating the climate impact of two university buildings in Sweden for life cycle phases A1-A5.1 and comparing the results to existing reference values. The results of the climate impact calculations are that the climate impact of Umeå Building is 30 kgCO2e/m2 Atemp, and Nya Konst is 31 kgCO2e/m2 Atemp. The result of the calculation of Umeå Building is based on Construction documents which makes for a sturdier foundation of the results while the result of Nya Konst is based on Project planning documents, that had less information available in them which makes the result more uncertain. The results also show that without a reference building to draw assumptions from when calculating the HVAC system with Project planning documents, it can be hard to achieve a high enough coverage rate to have a solid result. A hotspot analysis shows that by only calculating the six product groups with the largest climate impact for Umeå Building it would correspond to 81% of the total impact from the HVAC system and the calculations would be much quicker. The product groups not calculated could for example be accounted for with an add-on or by coverage rate. Several issues with performing this type of calculations are identified, such as the current lack of EPD´s, difficulties in processing the data provided through BIM-models and the time-consuming work of locating weights and material content for the products. It is therefore suggested that it would be preferable to update the BIM-models to include weight and material content of the HVAC products. This would make the calculations easier and faster to carry out. If also the availability of EPD´s increased, it would also be possible to increase the certainty of the results.