Measuring Savings: A Postretrofit Analysis of 436 Chicago Bungalows

April 29, 2014

Since 2006, the Historic Chicago Bungalow Association (HCBA) has provided more than 2,500 energy efficiency grants to low- and moderate-income bungalow owners throughout the city of Chicago. The HCBA EnergySavers program supports the organization’s mission to help bring resources to members in an effort to help preserve, maintain, and improve comfort in these aging homes. However, after several years of utilizing modeled/presumed savings from the insulation and air sealing measures provided by the grant program, HCBA reached out to Elevate Energy for an energy use analysis to measure homeowners’ actual post-retrofit savings.

Two typical Chicago bungalows that make up the Bungalow Belt.

Photo and map of the Bungalow Belt by HCBA.

Map from 2012 used in HCBA’s targeted outreach in the bungalow-dense Auburn Gresham neighborhood shows current members, certifiable bungalows and past grant recipients.

Table 1: Energy Intensity of 307 Bungalows Compared to a Single-Family Home Sample

Figure 1. Gas use dominates bungalows' pre-retrofit energy use intensity.

Figure 2. Eighty-three percent of homes in the bungalow sample reduced gas use postretrofit.

Figure 3. Bungalow households that used more natural gas before the retrofit saved more.

Figure 4. Post-retrofit gas savings by household size.


The popularity of the Chicago bungalow grew with the city’s second wave of development and population growth in the early 20th century. The bungalow gained popularity in California as a comfortable and affordable single-family housing type and quickly made its way eastward across the United States. The style became popular in Chicago because it could be built en masse efficiently and it was easily adapted to the typical 25-foot x 125-foot Chicago lot. Unlike the precursor to the Chicago bungalow, the workers cottage, bungalows featured a slightly larger footprint, which provided space for modern, larger living spaces and bedrooms. During this period between 1910-1940, an estimated 80,000 bungalows were built in the outer ring neighborhoods of Chicago—what is known today as the Bungalow Belt.

Today Chicago bungalows are widely recognized as social, economic, and structural city assets. They remain a popular choice for 21st Century families with reasonably sized living spaces, generous green space, and a flexible plan that can be adapted to suit homeowners needs. The high quality solid masonry construction cannot be replicated affordably today and is worth preserving for future families and communities. Mayor Richard M. Daley founded HCBA in 2000 to help preserve and promote this housing style, recognizing the importance of the bungalow to Chicago neighborhoods. Daley—who grew up in a Chicago bungalow—hoped that by promoting Chicago bungalows, the HCBA would help build a sense of pride in bungalow ownership. Homeowners would in turn work to preserve and maintain their historic bungalows, which would also help to strengthen the critical Chicago communities in which they were built.

To help support targeted outreach efforts, HCBA uses property assessor data to identify potential members and homeowners who are eligible for the Association’s grants and programs. Working with the Cook County Assessor’s office, HCBA acquired a list of 70,000 properties with home characteristics similar to those of Chicago bungalows to determine the exact number of extant certifiable Chicago bungalows. Once homes are determined to meet the criteria for being defined as an historic Chicago bungalow, HCBA develops maps of the bungalow communities. These maps show where potential members, current members, and grant recipients respectively are located.

Since 2010, HCBA has reviewed approximately 15,000 potential bungalows in 15 community areas. This “bungalow mapping” has helped the organization to support grant outreach and build membership. The critical value of this mapping project is that it enables HCBA to access homeowners who do not know about the organization, especially hard-to-reach homeowners without access to the Internet, and inform them of programs to help maintain their homes.

Need for Energy Efficiency Upgrades

One of the key ways HCBA helps its 15,000 member homeowners keep their bungalows functional today is by improving their home’s energy efficiency. Chicago bungalows were often built with little to no attic insulation and often times, oversized and inefficient heating systems. As a result, bungalows today are, on average, ten percent more energy intensive per square foot than other single family homes in Chicago (see Table 1).

In recognizing the importance of improving the energy efficiency of these homes to help maintain their affordability and desirability for future generations, HCBA created the EnergySavers retrofit program to help homeowners make their homes more energy efficient and lower their utility bills. Two of the key goals of this program were to inform homeowners that the grant would help them reduce their energy use, making their bungalows more comfortable, and thus more desirable to live in, and to ensure that the retrofit was subsidized. Members were eligible for a grant of up to $4,000 for attic insulation and air-sealing measures, which was provided through utility funded grant programs. Since 2006, more than 2,500 homes have been upgraded through this program.

One of the successes of the EnergySavers program lies in the repetition in housing form. Though Chicago bungalows can vary slightly in design and floor area, the houses are constructed so similarly that a contractor can efficiently revise work plans from one house to the next. Experienced contractors know where to look for common energy savings opportunities and can tailor their work scopes accordingly. For instance, one of the most critical points of air sealing a bungalow is the sidewall, where cold air flows from basement to attic, causing drafts in the first-floor living spaces. Since all Chicago bungalows are masonry construction with only a 3/8-inch space between the exterior masonry wall and the lath-and-plaster interior wall, it is not cost-effective to insulate the wall cavity unless the plaster walls are removed and reframed. However, because all bungalows have this feature, HCBA contractors know how to access and seal the 3/8-inch gap to reduce side wall drafts and the measure cost for each project.

HCBA’s program success in the Auburn Gresham neighborhood demonstrates the organization’s effective outreach model. Using the bungalow mapping project, HCBA identified 2,650 certifiable Chicago bungalows for targeted marketing in Auburn Gresham, located in Chicago’s Southwest Side. HCBA has devoted considerable time to building community partnerships with established organizations, such as Neighborhood Housing Services’ 79th Street office and the Greater Auburn Gresham Development Corporation. These partnerships are integral to gaining credibility in the neighborhood and strengthening their targeting efforts. Since this outreach campaign began in 2012, HCBA has completed 235 energy efficiency retrofits in Auburn Gresham alone, for a total direct investment of over $825,000.

By targeting communities like Auburn Gresham, HCBA strives to achieve its goal of helping homeowners adapt their homes to the 21st century. “If by providing subsidized retrofits, we enable homeowners to pay utility bills and be more comfortable, HCBA hopes that this will encourage bungalow members to continue to invest in their bungalows,” explains Executive Director Mary Ellen Guest, “which in turn will make the neighborhood and city stronger in the long run.” The qualitative benefits of this program have been widely confirmed by past recipients, who continue to promote EnergySavers by word of mouth. Determining the quantitative benefits of the EnergySavers retrofit, however, required the help of another community partner.

Collaboration with Elevate Energy

HCBA enlisted Elevate Energy (formerly CNT Energy) to perform an energy use analysis of 436 homes that participated in the EnergySavers program between September 2010 and November 2011.

Elevate Energy’s mission is to help people do more with less energy. The organization designs and implements energy efficiency programs that reduce costs, protect the environment, and ensure the benefits of efficiency reach those who need them most. Elevate is widely recognized for its building energy retrofit services in the greater Chicago region and as a leader implementing two of the nation’s largest residential hourly electricity pricing programs. The partnership between HCBA and Elevate Energy was a natural fit, as the organizations have worked together for several years. Elevate Energy’s local efficiency programs serve many of the same Chicago communities that are served by HCBA, and the two organizations share a commitment to preserving the existing housing stock and ensuring its long-term affordability and sustainability for low- to moderate-income families.

The Elevate Energy analysis focused on a pre- and post-retrofit energy use analysis of the 436 retrofitted bungalows in the EnergySavers Program. The team analyzed pre-retrofit and 1 year post-retrofit gas and electricity use. All energy use was weather normalized. All homes used natural gas as heating fuel. Not all of the bungalows had clean, full year pre- and post-retrofit data. The sample included 370 homes with gas data, 325 homes with electricity data, and 307 homes with whole building gas and electricity data.

In addition to energy use analysis, Elevate Energy looked for patterns in energy savings, measures received, dollars spent, air infiltration reduction, household income, household size, HVAC systems, and contractors. The team found energy savings correlations with air infiltration reduction and household size. They found no clear or statistically significant trends in the other variables.

The Elevate Energy analysis also compared energy use in pre-retrofit bungalows to energy use in other single-family homes locally and nationally. For the local comparison, Elevate Energy referenced its previously analyzed energy use of 200,037 single family homes in Chicago, with 75% of its stock built before 1954 and a median year built of 1926. This Chicago single family home sample included both frame and brick homes. For the national comparisons, Elevate Energy compared bungalows to single family home energy use from the Residential Energy Consumption Survey’s five state East North Central region (Illinois, Indiana, Michigan, Ohio, and Wisconsin) and its Midwest climate region (Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, South Dakota, and Wisconsin).

Analyses of large samples of homogenous building types, such as the Chicago bungalow, are extremely valuable to building scientists, energy efficiency service providers and policy makers. Because energy use varies widely, depending on individual building and household conditions, large datasets, such as the local Elevate Energy datasets referenced in Table 1, are useful to help describe a population of homes. These large datasets help to remove the effect of outliers, and can help define “typical” performance by housing type.

Context is important. Homeowners have a general understanding of the factors that determine energy use in homes. They understand, for example, that small homes often use less energy than large homes; that homes in Chicago use energy differently than homes in Arizona; that how a home is maintained affects energy use; and that changes in behavior and lifestyle can save energy. But they must usually hire an energy auditor if they want to make informed energy investments specific to their type of home. Few efficiency programs are able to provide local benchmarks for comparing one home’s energy use with the energy use of the same type of home or a large sample of its single family housing population.

Analysis Results

Finding 1: Preretrofit bungalows were more gas intensive and less electricity intensive than typical Chicago single-family homes. The energy intensity of the sample bungalows and single-family homes in this region is driven primarily by gas use. Preretrofit, median annual gas use was 1,624 therms for the 370 bungalows that had at least one year of clean gas data. Minimum use was 691 therms; maximum use was 3018 therms.

Preretrofit, median annual electricity use was 7,646 kWh for the 325 homes in the bungalow sample that had one year of clean electricity data. Minimum use was 2,045 kWh; maximum use was 22,681 kWh. These households use approximately 25% less electricity than typical single-family households in Chicago. The bulk of the bungalow analysis focused on gas use and savings because the installed measures primarily targeted gas reduction, and because electricity is less a driver of energy intensity than gas (Figure 1). However, it is worth noting that postretrofit, 62.8% of the homes reduced their electricity use (kWh). Median savings in electricity use for all homes were 5.5%.

Finding 2: Overall, 83% of the homes reduced their gas use after retrofit. Overall, 83% of the homes reduced their gas use after retrofit (308 of the 370 homes) (Figure 2). The median therms savings = 8.9%. Sixty two homes increased their gas use a median of 4.5% half percent. Eighteen percent of the homes saved greater than 20%.

Finding 3: Homes that consumed more gas and were leakier pre-retrofit saved more than homes that consumed less gas and were tighter pre-retrofit. The households that used more natural gas before the retrofit saved more (Figure 3).

Though there was a lot of scatter and the correlation was weak, households with higher air infiltration with measured CFM50 values greater than the median of 5,478 CFM50 demonstrated higher gas savings (P-value =.049). These findings are consistent with national evaluations, such as the weatherization program evaluations. In addition, two- to four-person households were likely to save more gas than either single-person households or large households (Figure 4). The program serves many retirees, and 32% of the participants in this sample were single-person households.

Finding 4: Bungalow sample representative of local datasets, but not national datasets. The pre-retrofit gas use in the bungalow sample was significantly higher than other comparative data sets. For instance, the 370 sample bungalows consumed 17.5% more natural gas than the Chicago single family home median (n = 200,037); 77% more than the Residential Energy Consumption Survey’s five state East North Central region (Illinois, Indiana, Michigan, Ohio and Wisconsin); and 85% more than typical homes in the Residential Energy Consumption Survey’s Midwest climate region (Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, South Dakota, and Wisconsin). This finding implies that bungalows as a housing type in Chicago, both by its pre-retrofit gas use and their prevalence, offer significant energy savings opportunities.

Finding 5. HCBA is targeting its EnergySavers program in areas where energy affordability is an important issue. Elevate Energy mapped the distribution of participant homes across the city by pre-retrofit gas usage and found that the pre-retrofit gas use of the bungalow sample was evenly distributed across the city with the exception of the highest gas users—defined as homes with use greater than 2,154 therms annually (well above the median Chicago single family home gas use of 1,382 therms per year). Many of these high gas use homes cluster in a three communities—Auburn Gresham, Washington Heights, and South Chicago—where area median income ranges from $30,000 to $50,000. HCBA is active in these communities, targeting grants to homeowners in areas where energy costs consume a higher percentage of household income. This has a huge impact on affordability for homeowners struggling to stay afloat with low to moderate household incomes.

Follow-up Interviews

Although HCBA had hoped for greater gas savings, they recognized the findings of the utility analysis provided by Elevate Energy as an opportunity to learn more about homeowners’ experiences with the program. Because all the bungalows received similar measures and the organization’s goal is to make these energy-intensive houses more affordable, HCBA hoped to find explicit areas where homeowners could be encouraged to take action to save more.

Accompanied by contractor DNR Construction, HCBA staff members visited 14 homes over four days in May and June 2012 to interview homeowners and test the mechanical systems. They visited 7 homes with savings greater than 10%, 4 homes with savings of 0–10%; and 3 homes with negative savings. As a membership organization, HCBA has an extremely engaged community and homeowners amenable to the additional site visits. Homeowners were asked questions about changes in occupancy, type of thermostat, temperature settings, and so forth. Notes about the layout of home (finished attics or basement, number of bedrooms, and so forth) were also recorded. In addition, DNR Construction tested the gross and net efficiency of the boiler or furnace and clocked the gas meter to verify that the ductwork was sized correctly and that heat was coming out of the heat delivery system appropriately.

Some of the trends that were found during the 14 site visits further explain the energy- intensive homes that demonstrate significant savings post-retrofit, as shown in the energy use analysis. For instance, of the homes visited, pre-retrofit high energy users who saved significantly often had heating systems that were only 80–90% efficient, but their thermostats were set at a consistent temperature throughout the day and night. For example, Bobbie F., who used 1,732 therms annually pre-retrofit, reduced her use by 29.3%, and kept her thermostat set at a constant temperature. However, she did have a new boiler installed just after the retrofit, which may have contributed to her significant energy savings.

Interestingly, other pre-retrofit high energy users who saved significantly also had either newer or frequently serviced mechanical systems. After these site visits in 2012, HCBA began incorporating boiler and furnace tune-ups into the EnergySavers grant, in effort to increase potential energy savings. However, homeowners’ active attempts to save energy—for example, by turning down the thermostat at night and when the homeowner was away—had not significantly changed since the retrofit. Encouraging homeowners to take small steps like this could make the difference in increased energy savings that programs such as these strive for.

Next Steps

HCBA would like to continue to track the performance of EnergySavers program recipients’ energy use post retrofit, to examine potential changes in homeowners’ role in energy saving habits, and at a later time determine whether these homes recapture value at time of sale. Additionally, HCBA hopes to administer a comprehensive occupant survey that will address occupant comfort and other non-energy-related benefits as well as changes in occupancy and other occupant behavior, and will continue to monitor post-retrofit utility results in order to improve its programs in the future. Possible improvements may include adjusting or replacing the mechanical system, educating homeowners about additional ways to reduce energy use, and perhaps testing advanced air-sealing and insulation measures to achieve deeper savings.

In conjunction with the measures installed through the EnergySavers grant, HCBA will continue to promote additional measures that clearly help homeowners save energy. These measures include installing high-efficiency HVAC systems and educating homeowners on small steps that they can easily take, such as using programmable thermostats and installing pipe insulation, faucet aerators, and so forth. HCBA hopes that all of these measures, taken together, will make additional savings available to grant recipients.

Program Take-Aways

At a program level, analyzing homes by building type can be used to direct cost-effective outreach and target clusters of homes in specific neighborhoods, much as HCBA has done in Auburn Gresham. Many municipalities have their equivalent of the Chicago bungalow—Philadelphia row houses, New Orleans shotgun cottages, Harlem brownstones, California atomic ranches, and so forth. While the vernacular architecture may vary across the United States, this methodology can be replicated. Municipalities can use this approach to target limited efficiency resources to the housing types that are most able to provide deep savings. This approach can also be used to combine energy efficiency with other municipality priorities, such as redevelopment zones, neighborhood stabilization, housing preservation, tax increment financing districts, and so forth, coordinating and maximizing the impact of public dollars.

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Get more information on HCBA.

Learn more about Elevate Energy.

Bungalows are energy intensive, and low-income homeowners feel it the most. Knowing this, HCBA continues to focus its outreach efforts on helping bungalow owners save energy and preserve their homes. The analysis described in this article may help residential efficiency program implementers and policymakers to approach energy efficiency at a community scale and explore programs that not only install energy conservation measures and encourage changes in behavior on the part of the homeowner, but also preserve the existing housing stock.

Emily Bailey Burns is the grants manager for HCBA. Rachel Scheu is Elevate Energy’s research director.

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