Affordability, Sustainability, & Efficiency: How energy intersects with housing 

My name is Rachel Kelly and I joined CUB in September 2024 as an outreach intern. I am a senior Japanese and English Major at Macalester College. Last summer I had the privilege of conducting summer research on passive housing design in Japan with Professor James Doyle in the Macalester Physics department.  I wanted to share some of findings of this research as it relates to the work that CUB does around residential energy issues.  

Much of CUB’s outreach work focuses on helping people save money on their energy bills and making their homes more energy efficient. While we don’t focus on housing as a topic, issues of housing affordability and sustainable housing design come up directly and indirectly in our work. This article is the first of a series that explores the connection between reduced residential building energy use, housing affordability, and sustainable building practices. As we strive to address residential energy issues in Minnesota, it can be helpful to expand our perspective and look for inspiration around us and around the world. We hope you find this series of articles interesting and informative. 

Building Energy Use and Emissions  

Buildings of all types – commercial, industrial, and residential – contribute significantly to global greenhouse gas (GHG) emissions. The energy used to heat, cool, and power buildings accounts for 28% of global emissions, while the production and transportation of building construction materials accounts for another 11%. These percentages are also representative of the building-sector in the United States, with over 31% (1,966 million metric tons) of carbon emissions coming from residential and commercial buildings or building-related activities. Residential buildings account for about half of the building use and construction carbon footprint in the United States. Residential energy issues are both a focus of CUB’s work and a key element in my research on passive building design.    

To meet Minnesota’s climate goals, including the carbon free standard for 2040 and the net-zero economy goal for 2050, it is important to reduce the carbon impact of residential buildings. Decarbonization of the electricity grid, coupled with the electrification of home energy use, can in principle eliminate operational emissions and decrease construction emissions from buildings.     

Need for Affordable Housing  

A key challenge in reducing the total carbon impact of residential buildings is that we need more housing, especially affordable housing. Affordable housing is housing where the occupant is paying no more than 30% of their gross income on total housing costs, which includes the cost of utilities. In 2023, the National Low Income Housing Coalition found the U.S. needs almost 7 million more affordable housing units to support our 10.8 million extremely low-income families. Extremely low-income is defined as incomes at or below either the federal poverty guideline or 30% of their area median income, whichever is greater. According to the National Association of Realtors and Zillow, home prices have surged 39% and rents 31% over the last four years. Nowhere in the U.S. can a renter working full time on minimum wage afford a two-bedroom apartment, and 70% of extremely low-income families spend more than half their income on rent.   

Affordable housing is deeply interconnected with a high energy burden and inefficient housing stock.  In order to reduce a household's energy burden (the amount of income spent on energy), significant upgrades to the building shell are often needed. Increasing a home's efficiency and decarbonizing its energy use can be a costly endeavor - often many thousands of dollars. These projects can be disruptive and, even when they may pay off over time, for families that already struggle to afford housing, these costs can be hard. As such, energy efficiency during the design and construction phase is a key aspect of a sustainable and affordable home design. 

Sustainable and Healthy Housing  

In addition to being environmentally sustainable and affordable, housing should also be comfortable and healthy. According to the American Lung Association, Americans spend 90% of their time indoors. At minimum, adequate ventilation of homes to maintain indoor air quality is an essential consideration for any sustainable design. However, ventilation must be balanced against heat loss or gain that could contribute to heating and cooling loads.    

From a health perspective, the use of natural gas in homes is problematic, especially in homes lacking adequate ventilation. Burning natural gas produces nitrogen dioxide which reduces lung function, inflames airways, increases asthma attacks, and generally exacerbates respiratory problems. There is now significant evidence linking cooking with gas and childhood asthma, including a study from 2023 that found that children living in homes with gas stoves face a 42% increased risk of asthma symptoms and a 24% increased risk of an asthma diagnosis in their lifetimes.   

Interconnections 

Energy efficiency, decarbonization, and affordable housing are interconnected issues. During the course of my summer research, I learned that models of both traditional and modern architecture from places like Japan may offer insights to increase home efficiency, home comfort, and connection to the natural environment in urban settings. Next, this series will delve more into traditional Japanese design, passive heating and cooling, ecological design, and how these concepts might apply to Minnesota housing. Stay tuned!