The lowest carbon HVAC system could be no system: the design and lifecycle comparison of two heating and cooling options for Canada’s first hempcrete institutional building

This paper presents a comparative analysis of lifecycle carbon for two heating and cooling system options: a reversible ductless split ASHP and direct electric baseboards with a radiative cooling paint. It was determined that over a 60-year assessment period including refrigerant leakage, the ASHP contributed between 2 and 7 times the lifecycle carbon of the direct electric, depending on the consideration of the cooling paint. A sensitivity analysis found that the electrical emission factor of the grid and the refrigerant type and leakage reduction measures both had a strong influence on the lifecycle carbon comparison of the two options. The findings of this study are intended to continue advancing the discussion of the true lifecycle carbon impact that mechanical systems contribute to overall building emissions.