Employee Comfort Versus Energy Efficiency? Or Can You Have Both?

By Stefan Flagner

What is one of the factors that substantially contributes to the energy consumption of a building? It is keeping the indoor temperature at a comfortable level. A report by the US Department of Energy determined that around 35% of total building energy costs are from heating, ventilation and air conditioning. Thus, keeping the temperature in the office stable substantially decreases energy efficiency. However, that assumes there is just one specific temperature level and it’s best to keep the indoor temperature stable at this level.

Recent research draws another picture: its findings suggest that creating a dynamic indoor temperature is beneficial for human health and perceived comfort. A study published this year by colleagues from Maastricht University’s Health Faculty investigated the effect of temperature drift on human health and comfort. In their study, they adapted the room temperature in an 8-hour period from just 17 °C (62.6 °F) at 9 am to a maximum temperature of 25 °C (77 °F) during midday and allowed it to drop again to 17 °C towards the end of the day, at 5 pm.

Graph 01

The study finds that a dynamically changing indoor temperature, as compared to a stable fixation at 21 °C (69.8 °F) significantly increases calory use (per kilo). This energy expenditure is an important indicator for health, with high levels, in the long run, being a strong predictor for the development of obesity, heart problems, and diabetes. These health problems are also linked with short-term negative health issues, increasing the risk and length of humans being on sick leave. Additionally, the study measured perceived discomfort and showed that a moderate temperature drift of around 2.5 °C (36.5 °F) per hour did not substantially reduce occupants’ perceived discomfort.

Closing the loop, what does this mean for real estate developers, and ultimately investors? It can be an opportunity to reduce the energy costs from heating and cooling commercial buildings by allowing for a dynamic temperature drift during the day, while still providing occupants with a comfortable feeling and improving their health. For employers, this can be directly translated to a more productive and healthier workforce and reduced costs from absenteeism.

Paper about temperature drift (Ivanova, Pallubinsky, Kramer & Marken-Lichtenbelt, 2021)

US Department of Energy Report