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Demystifying New Mechanical Systems for Built Green Buildings: HRVs and Heat Pumps

Guest post by Aaron Barnett, Cascade Built’s Comfort Systems division

In the highly competitive Seattle-area building market, builders need to take advantage of every available opportunity. The Built Green program offers significant advantages for builders who understand it well, including expedited permitting and additional floor area in the City of Seattle and other nearby jurisdictions.

One way to meet Built Green standards that provide client satisfaction as well as builder advantages is the use of cutting-edge mechanical systems. Heat recovery ventilators (HRV) supply continuous fresh air to the living spaces of a home and control humidity. Heat pumps provide highly efficient space heating and cooling without introducing combustion products into the home. Heat pump water heaters can offer excellent efficiency and greater hot water availability than other systems. However, realizing these benefits requires that these systems are designed and implemented correctly. The post will dive into the benefits of these systems, how they can help a project achieve Built Green certification, and how to plan and install them correctly.

Cascade Built's View Haus 5 townhome complex features mini splits and HRVs. It was Built Green 5-Star certified in 2015.
Cascade Built's View Haus 5 townhome complex features mini splits and HRVs. It was Built Green 5-Star certified in 2015.

Heat pump systems are rapidly growing in popularity due to their efficiency and their ability to deliver both heating and cooling in one package. As summer temperatures rise in the Northwest, the demand from clients for cooling has risen as well. Heat pumps are much more efficient than current furnace and resistance systems due to the fact that they harvest energy from the ambient air outside the building. Heat pumps come in a variety of configurations and sizes and the systems can be scaled to serve loads ranging from small apartments to large commercial and multifamily applications. Correct design is key for these systems and Built Green encourages the use of Manual D and Manual J calculations in the design process, which will dramatically improve the efficiency, comfort, and durability of the home. Built Green also awards significant points for using ductless heat pumps, and additional points for using high quality ones that include features such as the ENERGY STAR label, ECM motors, and zonal controls—features which are commonly available on reputable equipment. 

Heat recovery ventilators complement any high-quality build, providing better energy efficiency and radically improved indoor air quality. An HRV runs continuously, bringing in fresh air from outside and exhausting stale air from inside. It uses a heat exchanger to conserve the energy that has been put into conditioning the air inside the home and filters all the air that passes through it, so allergens, dust, and other common pollutants are significantly reduced. HRVs provide benefits for all homes and Built Green offers five points for the installation of an HRV on its single-family/townhome checklist, but an HRV also becomes necessary for the proper functioning of a building built to comply with some of the more stringent Built Green envelope requirements. Indeed, installing an HRV is actually a requirement for Built Green’s highest certification level, Emerald Star.

Inside View Haus 5, a Mitsubishi mini split system blends in with the interior.
Inside View Haus 5, a Mitsubishi mini split system blends in with the interior.

While space heating generally represents the largest share of energy consumption, domestic hot water heating is another large component of that load. There are now a variety of heat pump hot water heaters available on the market. Most locate the heat pump itself as part of the tank assembly and function best when the intake and exhaust air for the heat pump is ducted to the building exterior. Built Green awards six points for the use of a heat pump hot water heater in a single-family or townhome context and significantly greater rewards for doing so in a multifamily project. 

There are many ways to achieve Built Green® certification, but few have as significant an impact on occupant comfort and energy efficiency as using high-quality mechanical systems. Integrating these systems into the building design at an early stage will reduce complexity and help your project obtain Built Green certification.


Aaron Barnett manages Cascade Comfort Systems, Cascade Built’s mechanical systems division. He’s an expert in high-performance mechanical installations and known for bringing a keen understanding of building complexities and construction. He can be reached at or 206.409.4948.

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