Beyond Energy: Justifying PHIUS+ for Affordable Housing

Affordable housing is a critical need for thriving, sustainable communities, enabling all residents access to a safe and stable place to call home. While public funding for new affordable housing developments often requires enhanced sustainable design, such as Green Communities, the current shortage of affordable housing has some calling for removing regulations that are perceived to have a higher first cost in order to funnel funds into more units of housing. In the midst of this debate, Precipitate served as the Certified Passive House Consultant for the Hook & Ladder development, 118 units of affordable housing currently under construction in Minneapolis. One building is standard construction and one is PHIUS+ 2015 pre-certified, going above current standards for energy efficiency in building design, particularly in the area of affordable housing.

Through working on the Hook & Ladder project, Elizabeth Turner from Precipitate and Lindsey Kieffaber from the projects's architecture team at LHB discovered that there are many benefits beyond energy efficiency to utilizing the PHIUS+ standard for affordable housing. The pair wrote a paper on the topic, Beyond Energy: Justifying PHIUS for Affordable Housing, which they recently presented at the Thirteenth Annual North American Passive House Conference in Boston in September 2018. Presentations typically focus on technical details of getting passive projects built, from envelope details to mechanical systems and energy modeling. However, given an affordable housing crisis that is only growing, there is a discussion on whether public funds should be spent on more units of affordable housing, or on passive house certified housing. If energy efficiency were the only item at stake, perhaps it would make sense to spend the money on affordable housing. But considering the multiple benefits for occupants, owners, and the community, the recommendation is that pursuing PHIUS certification is a worthwhile investment of public funds.

Passive Strategies

Strategies aimed at improving the energy efficiency of passive multifamily buildings also result in benefits for occupants, owners, and the community. While we don't have data specific to PHIUS projects, the Green & Healthy Homes Initiative conducted a literature review, Non-Energy Benefits of Energy Efficiency and Weatherization Programs in Multifamily Housing, which outlines outcomes of energy efficiency programs and served as a basis of data to inform our research. So what's different about PHIUS+ certified buildings?

  • Higher-than-code levels of insulation reduces the energy it takes to heat and cool the building, and keeps the building at a more steady temperature leading to greater thermal comfort for residents. The insulation also makes buildings hold their temperature in case of power outages, like a thermos, making them more resilient in extreme weather events and keeping residents safer.

  • Continuous exterior insulation and elimination of thermal bridges means fewer cold spots, allowing residents to cozy up to the window even in the middle of winter - and feel comfortable with the thermostat set a few degrees lower, too. The buildings are extremely airtight - and must pass an airtightness test to be certified.

  • The building envelope (walls, roof, windows, etc.) is designed to prevent moisture from condensing and getting trapped inside without the ability to dry out. This results in a more durable envelope with reduced chance for mold and mildew to develop. Less risk of building envelope failure and healthier indoor air for residents? Win - win.

  • In traditionally designed buildings, fresh air is often delivered to resident units only when there is a demand for heating or cooling. In a PHIUS+ building, there is a requirement to continually deliver fresh air to units. Fresh air must be delivered directly to bedrooms so that occupants can receive fresh air even with bedroom doors closed. The fresh air provides more oxygen and removes contaminants.

  • This fresh air must be filtered with a minimum MERV 8 filter (MERV 12 is recommended) which protects the inner workings of the energy recovery ventilator and also removes particulates from the air, which provides healthier air particularly for residents with allergies and asthma.

  • A third-party verifier ensures that the buildings are built as designed and as modeled, helping them perform better and reducing risk for the building owner.

  • Domestic hot water (DHW) must be carefully designed to minimize wasted energy, with the side benefit of less wasted water. Less waste of hot water results in lower energy and water utility bills.

Occupant Benefits

While at first glance the PHIUS+ certified building may seem like a typical apartment, it is anticipated that occupants in the building will experience higher levels of health and comfort due to the reduction in mold, bacteria, and dust, and more stable temperature throughout the unit. The focus on air tightness and continuous ventilation can lead to cleaner air inside buildings near more polluted sites, where affordable housing often ends up. With more energy efficiency comes more stability in energy bills, which vary less with fluctuations in weather or energy price. These benefits all can have positive impacts on cardiovascular health and stress as well.

Owner Benefits

Fostering happy and healthy residents is likely to lead to less turnover in units, a major property management expense. While there are higher upfront construction costs for PHUS+ certified buildings (estimates range from 0% - 15%), the commitment to the pursuit of PHIUS+ can result in additional funding or funding preference, and receives additional points in the competition for affordable housing tax credits in some states like Pennsylvania. It remains to be seen if PHIUS+ will result in lower maintenance and operation costs, but with the enhanced and third-party verified envelope, this is a likely scenario.

Community Benefits

When more community members have safe, stable housing, the whole community benefits. Lower turnover may lead to more community engagement, and residents who have more housing stability in turn have more funds to support the local economy. As renters make up a greater share of vulnerable populations, utilizing the PHIUS+ standard for affordable housing supports people in communities who are in greatest need of support. At a larger scale, energy efficient housing produces less carbon emissions and is more resilient to extreme weather events and uncertain futures.

While the focus of the passive house PHIUS+ 2015 is on reducing energy consumption cost-effectively, designing projects to meet the standard also impacts critical issues we're dealing with as a society today. In order to gain broader support for passive building and engage people whose concerns range beyond energy, advocates should discuss the full spectrum of benefits that PHIUS+ buildings bring to occupants, owners, and our communities.

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