Overview

30PRL is one of several all-electric projects that Boulder Housing Partners has completed. The development is located within the city’s first Transit-Oriented Development district. Construction of 30PRL began in late 2019 and it was placed into service in 2021. Of 30PRL’s 120 units of affordable housing, 20 are set aside for an independent living program serving individuals with intellectual and developmental disabilities through a partnership with Parker Personal Care Homes, and an additional 10 units are set aside to support individuals and families exiting homelessness.

Planning and Design Approach

The decision to pursue an all-electric design for 30PRL was driven by several factors, including building energy code requirements, BHP’s mission and values, and cost. Boulder is one of Colorado’s jurisdictions that has adopted a high-efficiency energy code to reduce carbon emissions from buildings and promote healthier and more sustainable homes. BHP credits local building energy codes for incentivizing all-electric design for new construction projects. Importantly, BHP is a mission-driven organization working to develop a decarbonization plan and achieve net zero energy across their portfolio, which contributed to the decision to adopt an all-electric design for 30PRL. Finally, because the five-acre lot that 30PRL is situated on was formerly a car lot, installing the gas lines needed for residential development was cost-prohibitive, further affirming the choice to pursue an all-electric design.

Electrification Strategies and Features

30PRL’s electric water heating is achieved with heat pump water heaters (HPWH) located in mechanical closets in each dwelling unit. The mechanical closets feature Louver doors, which allow for sufficient air intake and exhaust for the HPWH to function. HPWHs are considered highly efficient, operating at nearly triple the efficiency of traditional electric resistance water heaters. This efficiency contributed to the decision to use HPWHs in 30PRL, despite the higher upfront cost and more involved design approach compared to electric resistance water heaters.

For space heating, 30PRL uses a hydronic Aquatherm system which connects to each HPWH and uses the hot water to deliver heated air throughout the apartment. Because these systems do not provide cooling, 30PRL utilizes a separate, split system condensing unit on the roof for air conditioning.

30PRL also utilizes a central energy ventilation recovery (ERV), a best-in-class ventilation system. These ERVs are designed to exhaust air from the building and bring in outdoor air while transferring heat and humidity from one air stream to the other. This design improves heat recovery efficiency and reduces heating needs and operating costs otherwise needed for conditioning the outside air. These efficiency measures are especially important in Colorado, where the coldest days of the year can put additional strain on HVAC systems.

BHP uses electric, energy-efficient appliances across its portfolios. While these appliances, namely electric resistance stoves, improve indoor air quality for residents, the major draw for BHP has been simplified operations. BHP has found that it is easier for in-house maintenance to work on these electric appliances, and that electric stoves in particular reduce the risk of fires compared with gas stoves.

BHP did not face challenges procuring qualified installers and consultants who were familiar and experienced with electric water heating and space heating systems. They found that the systems utilized at 30PRL were relatively simple and the installation of such systems were similar to conventional systems. Being in a large metro area, BHP has seen more contractors that are familiar with building electrification technologies.

Cost

The total development cost for 30PRL was $53,353,161. BHP, like other developers pursuing the electrification of their portfolios, has reported that it can cost slightly more upfront to utilize all-electric mechanicals. However, as electric domestic hot water (DHW) and HVAC systems become more widely adopted, the cost difference between constructing all-electric and mixed-fuel buildings may decrease.

Visit our resource finder to explore funding, financing, and incentive opportunities for the electrification of multifamily affordable housing.

Successes

30PRL has demonstrated that all-electric multifamily affordable housing development is possible in the Denver metro area. 30PRL is part of a master planned, five-acre, all-electric community, including both affordable and market-rate residential units. BHP considers this all-electric neighborhood to be an example that demonstrates the viability of large-scale all-electric developments. The 30PRL design team also considers the quality and aesthetics of the development to be successful, as the affordable housing is not easily distinguishable from the market rate housing in the neighborhood.

Lessons Learned

While 30PRL has been successful in many ways, there are lessons that BHP and their design team have learned since the building has been placed in service that will influence how they approach the design of their next property.

The heat pump water heaters (HPWH) have not been as well received by residents as anticipated at 30PRL. Residents have reported that the in-unit HPWHs in their units can be louder than expected, and maintenance staff have even been asked by some residents to turn them off. In these cases, maintenance staff have switched the HPWHs to function as electric resistance water heaters, which are three to four times less efficient but preserve the functionality of the Aquatherm space heating component. The HPWHs also exhaust cold air as a necessary part of their function, and the louvered doors that are designed to allow airflow into and out of the closet can cause some comfort issues for residents. BHP shared that design changes can alleviate both concerns and in future developments BHP will locate mechanical closets containing HPWHs in common corridors rather than each apartment. This will allow cool air to be exhausted into the corridors rather than the apartments and will mean that any noise produced by the HPWHs will be insulated by a wall between the closet and the apartment, rather than a louvered door. An additional benefit is that maintenance staff will be able to access the mechanical closets without entering any apartments, benefiting both operations and residents. 

There were also some issues encountered with utility metering due to incorrect installation. 30PRL initially used submeters so each resident could pay for their own heat and hot water in exchange for a lower monthly rent. During the submeter installation, however, lines were physically crossed, leading to inaccurate billing. BHP attributes this to installers who were unfamiliar with the equipment and is in the process of exploring a transition to owner-paid utilities at 30PRL. Submetering is a method for minimizing the administrative burden of utility metering. As evidenced at 30PRL, however, experienced installers are crucial to enjoying these benefits.

BHP’s biggest piece of advice for multifamily developers, owners, and operators considering all-electric design is to work with experienced consultants, especially seasoned mechanical, electrical, and plumbing (MEP) specialists.