Getting Beyond Widgets: Performance of Efficient Indoor Air Quality System Retrofit Packages for Schools

School facilities are often underfunded with aging and poorly maintained HVAC and lighting systems. Most existing school buildings stand to benefit significantly from retrofits in terms of energy, cost, and emissions savings. Ventilation and indoor air quality (IAQ), which are important aspects of a healthy and productive learning environment, can also be enhanced by some energy efficiency measures (EEMs). Packaging energy efficiency and IAQ systems retrofits may represent a golden opportunity to improve performance in this critical building sector.

Retrofit projects and utility incentive programs typically emphasize only energy savings and are often component-based, targeting upgrades of one piece of equipment or control sequence at a time. The Beyond Widgets program, which addresses barriers to systems-based retrofit approaches, developed retrofit packages for schools with energy and IAQ benefits, combining EEMs vetted with a utility partner based on technical readiness, market availability, ease of implementation, energy savings potential, and other factors. EEMs included occupancy-based ventilation strategies, efficient lighting and controls, efficient supply air filtration, HVAC sequence improvements, retuning, and scheduling, as well as HVAC equipment upgrades. EEMs were combined into ten distinct packages representing a range of likely implementation costs and complexities, with the aim of packaging measures to improve overall cost-effectiveness and energy reduction impact versus performance of the individual EEMs.

Integrated system packages were evaluated for two climate zones - northern California (representative location: San Jose) and North Carolina (representative location: Charlotte) by comparing baseline and retrofit whole-building annual energy simulation results to derive annual energy and demand savings, utility cost savings, as well as carbon emission reductions. Energy savings were valued according to local utility rates. Generally, energy and carbon emissions savings were greater for the higher-cost, more comprehensive retrofit packages (i.e. packages involving more building systems and trades). Retrofit impacts ranged from 14% to 36% energy savings relative to the existing building baseline in the California case, and 13% to 36% savings in the North Carolina case. Simple payback results, calculated from modeled annual energy cost savings and estimated project implementation costs, ranged from around 6 to 11 years for early replacement scenarios and 1 to 5 years for normal replacement scenarios (only considering the incremental measure cost above code-compliant alternatives).