Impact of heating electrification and building retrofit on the indoor thermal environment and electricity demand

Abstract Retrofitting building stock through heating electrification and energy efficiency improvements is essential for achieving carbon neutrality. Understanding the effects of electrification and efficiency retrofits on building-resident satisfaction and adaptive behaviors is important, as these directly impact retrofitting success, adoption rates, energy consumption, and performance. There is a gap in understanding combined effects of heating electrification and building efficiency retrofits. Using data collected over 2.5 years, we performed integrated qualitative and quantitative analysis to evaluate combined heat pump electrification and roof insulation retrofitting in a 10-unit New York City apartment building. Building resident satisfaction with each strategy was assessed, and impacts on occupant thermal comfort, energy behavior, indoor thermal environment, and energy consumption were analyzed. Despite perceived challenges and resident skepticism, air source heat pumps (ASHP) provided adequate indoor thermal comfort. ASHPs were preferred over steam boiler heating for controllability, noise reduction, and improved thermal comfort. Unintended benefits included improved aesthetics, reduced real estate needs, and decreased burn potential. With heat pumps, some residents adopted energy-conservative behaviors while others adopted “comfort-taking” behaviors, prioritizing comfort over conservation. Roof insulation retrofit further improved resident thermal comfort and decreased total building heating energy requirements by 25.3-34.2% and heating peak power requirements by 10.7%. The retrofit also improved ASHP efficiency in previously uninsulated spaces, effectively mitigating heat pump undersizing effects. Combined energy retrofitting strategies could play a key role in ensuring thermal comfort and building energy efficiency toward carbon neutrality.