Optimizing HVAC System Settings to Reduce Energy Use

One of the simplest ways to reduce a portfolio’s energy use is to optimize HVAC operations in all facilities, minimizing excessive heating or cooling while maximizing occupant comfort. Optimization starts with two key policies: those for building temperature settings, and for HVAC system startup and shutdown times.

In response to a Member-Client request, SR Inc sent a survey to Member-Clients to determine common practices in these two areas of building operations in July 2012. The results are detailed in our forthcoming advisory Indoor Environmental Quality (IEQ) Settings: SBER Survey Results. The survey aimed to answer two main research questions:

1. What are common site-level policies for indoor temperature set points and ranges, compared across climate zones and building types?
2. How do Member-Clients vary HVAC operating hours, if at all, accounting for a) startup and shutdown times on weekdays and after weekends, and b) changes in the season?

50 SBER Member-Clients, and their building engineers and facility managers, responded to the survey. Most respondents answered for office buildings, with fewer than ten responses from other building types (including labs, mixed use spaces, and data centers). Some key findings from the survey include:

• In the summer months, most office respondents set temperatures at 74 degrees or below; 72 degrees is the most common setting in this building category. Additionally, the ranges allowed for interior temperature controls in offices are on average greater than those for other building types, indicating greater occupant control in offices.
• The largest proportion of office respondents initiate HVAC systems 2 hours before normal occupancy—3 hours before on Mondays.  Shutdown settings are more widely distributed, although a full 50% of office respondents shut down the building’s HVAC within 1 hour after occupancy.
• 23 (48%) respondents do not change settings with the change in season, while 18 (37.5%) respondents do change settings with changes to the season. Of the 7 respondents (14.5%) who sometimes change settings, two require 24-hour building operation (for laboratory spaces in mixed use buildings), while one actively adjusts settings based on occupancy and HVAC needs.

The results also indicate that temperature settings remain consistent across climate zones in the summer months, with greater variation between climate zones in the winter. Additionally, multiple SBER Member-Clients are implementing automated building controls and advanced software solutions, like those described in the SBER Briefing Implementing Intelligent Building System Software(2012) and SBER Report Advanced Energy Management Systems(2011). These solutions automatically respond to occupant comfort issues and optimize heating and cooling to improve energy-efficiency and cost-effectiveness.

To download a copy of the Indoor Environmental Quality (IEQ) Settings: SBER Survey Results Advisory click here to access SR Inc’s Member-Only Digital Library. To learn more about gaining access to the Digital Library for your company or organization, leave a note through our Inquiry Form or Contact Us directly. Is your building or portfolio’s HVAC policy different from SR Inc’s survey respondents? Leave a comment below to tell us about it.

SR Inc Contact: Andrew Reovan, Sustainability Analyst (andrewreovan@sustainround.com)