Very High Efficiency (VHE) HVAC retrofits for commercial buildings
Space conditioning and ventilation account for 45% of all energy use in commercial buildings within the U.S., but many commercial HVAC systems are wasting much of that energy. Even when building owners upgrade their equipment, retrofits often focus on one-for-one replacement, wasting yet another opportunity to improve the building's efficiency.
In a project led by the Institute for Market Transformation for ComEd Customer Innovation, Slipstream will help prove an innovative approach known as Very High Efficiency (VHE) HVAC in commercial building retrofits. We estimate this approach could cut HVAC energy use in half across a majority of all commercial building floor areas, which would go a long way toward helping building owners meet their ambitious energy efficiency goals.
What is VHE HVAC?
Very High Efficiency (VHE) HVAC is a specification to design, engineer, and install a whole-building HVAC system that minimizes overall cost, energy use, and refrigerant volume while maximizing occupants' safety and comfort.
While strategies may vary depending on a building's needs, VHE HVAC elements typically include:
- Complete separation of ventilation air from conditioned air
- Specialized, efficient equipment, such as heat pumps for heating/cooling and energy recovery ventilators
- Separate air flow zones and multiple independent zones
- Smaller systems and ducts than typical HVAC
- High-quality (MERV-13) filters to protect indoor air quality
- Detailed system commissioning, including duct sealing and leakage testing
In many cases, building owners can expect to see HVAC-related energy reductions of 50% or more in applicable buildings as well as peak demand reductions of up to 40%. Building occupants, meanwhile, can enjoy the improved comfort and indoor air quality from the installation of highly controllable ventilation systems. Moreover, VHE HVAC systems can serve as a path to decarbonization, as the process enables the electrification of heating systems without increasing electricity demand.
About the project
Led by the Institute for Market Transformation, this project will test the VHE HVAC approach for retrofits of commercial buildings. Using a set of real-world buildings, the project team will evaluate the VHE HVAC process from conception to completion, with the overall goal of understanding potential savings, cost effectiveness for customers, and pathways to integrate the approach into the ComEd Energy Efficiency Program.
The project includes multiple phases:
Program investigation and site selection:
The project team will recruit a sample of buildings within ComEd’s service territory that fit the project criteria.
Measurement and verification:
Slipstream will develop a written M&V plan for each site that describes the measurement program and protocols for continuous monitoring and evaluation of the demonstration, both pre- and post-installation. The data the project team plan to collect include:
- For each building: 12 months of prior utility bills, building demand, size, form/shape, use type, occupancy level, and hours of operation.
- For each existing HVAC system: capacity, zoning, control system, design intent, and equipment data type, number, capacity, and year of manufacture.
Along with energy use, we will monitor indoor air quality to compare the existing system's ventilation against the retrofit system—a data point that's particularly important as we strive to make commercial buildings safer in the post-pandemic future.
At each phase of the process—baseline, design, installation, and end use—Slipstream will collect qualitative data from various stakeholders to better understand the issues affecting a VHE HVAC retrofit. Through conversations with facility staff, the design team, installers, and occupants, we will better understand the issues behind VHE HVAC retrofits and help program managers incorporate VHE HVAC into their energy efficiency portfolio.
- Does the VHE HVAC systems approach provide the same level of performance in Chicago's climate and buildings as it has in limited testing in other climates?
- What is the cost to provide this level of performance relative to typical system installations?
- Is backup resistance heat necessary at any time to maintain occupant comfort?
- Does VHE HVAC provide a healthier and more comfortable indoor environment than typical HVAC systems?