The concept of “energy poverty” is recognized when a household spends more than ten percent of its income on energy-related expenses. In low-income neighborhoods and families, energy poverty is more prevalent, as energy costs and income are not necessarily directly correlated. Figure 1 shows a section of a map of the United States detailing energy expenditures of those in poverty. The map section below highlights St. Louis County.Figure 1: In St. Louis county, those below 50% of the federal poverty level spend an average of 26.8% of their income on energy bills (The Atlantic).

Many low-income multifamily housing facilities lack the insulation and structural integrity of non-low-income apartments and houses, thus spending more proportionally on heating and cooling[i]. Heating, ventilation, and air conditioning (HVAC) accounts for approximately half of energy expenditures in the average US home, making it the largest proportion of the average energy bill.[ii]

The broad objective of this project was find ways to make environmentally friendly building practices accessible to people across income levels, specifically in the St. Louis area. The original proposal focused on HVAC solutions and efficient building upgrades, but the scope was broadened to include renewable energy sources, specifically geothermal and solar photovoltaic (PV). Case studies that focused on low-income housing and sustainability exemplify facilities that have been built or renovated with efficient and renewable technologies. They all save energy (which can be converted to emissions savings as in section 6.4) and operation costs for residents.

Habitat For Humanity St. Louis[iii] builds affordable single-family homes in the St. Louis region. Since their 2008 Leadership in Energy and Environmental Design (LEED) certification, nearly every Habitat home in St. Louis has been built to LEED Platinum standards. Due to their existing environmentally conscious practices, the next logical step would be looking at incorporating renewable energy generation to further decrease the cost burden and emissions from residential electricity.

The project looks at the potential of installing small-scale solar arrays on Habitat STL’s homes. Simulation is an important tool for theoretical tools and predictions. Originally, Hybrid Optimization of Multiple Energy Resources (HOMER) was to be used as a simulation tool. However, HOMER’s calculations exceed what is required in many cases, and MATLAB can be used as an alternative to return important values and projections. Additionally, HOMER’s license is expensive to renew, so a MATLAB program that can accomplish all of the necessary calculations serves as a good alternative.

The MATLAB program referenced in this report calculates upfront cost for different sized solar arrays and the levelized cost of solar energy based on array size and current per-watt costs of installation. In accordance with existing studies, future cost projections of both solar and utility electricity were calculated along with emissions savings and cost savings.

Habitat For Humanity St. Louis

Habitat For Humanity serves low-income individuals worldwide, providing quality housing at low cost. St. Louis is a great location for Habitat’s operation because it is an urban setting, but land is readily available to build on. They do not have to fight others for space to build and land is not outrageously expensive. Habitat incorporates new construction into existing communities so residents can move into a neighborhood that has already been established. 

In some locations across the country, solar has been installed on Habitat homes. In the Metro Maryland chapter, a 4.2 kW array was installed on one home in 2016[i]. Under Maryland conditions and policies, the array is projected to save $20,000 and 70,000 lbs. of CO2 emissions over the 20-year system lifetime.

Habitat St. Louis has other sustainable operations including its ReStore[ii], which offers old or unused appliances and building materials. ReStore diverts building material from landfills and allows new building projects to be sustainably sources. While this practice does not specifically tie into energy conservation in buildings, Habitat St. Louis’s commitment to sustainability makes them a good candidate for bigger environmentally conscious projects.

[i] Chandler, A. “Where the Poor Spend More than 10 percent of their Income”. The Atlantic, 2016.

[ii] “Heating & Cooling”. US Dept. of Energy, 2018.

[iii] Habitat for Humanity St. Louis

[i] Direct Solar Energy (April 2016). “Direct Solar and Habitat for Humanity Team Up to Power the American Dream”. Retrieved from

[ii] Habitat for Humanity St. Louis: ReStore.