Energy Efficiency Guide for Congregations

Nov 24, 2021 | Blog

By Jerry Bernstein and Anne Gerrietts

This planet is our only home and many congregations of all faiths, Interfaith Power and Light (IPL) members and non-members, are committed to safeguarding it for the present and future generations.  Congregational efforts typically include one or more carbon reduction projects, reduced resource consumption programs and habitat restoration.  This guide provides a summary of carbon reduction strategies used by congregations and others to improve energy efficiency (to reduce operating costs while reducing carbon emissions).   

The phrase “reduce then produce” remains relevant in many locations.  In our experience, we’ve found energy efficiency improvements such as LED lighting systems have 1 ½ – to 3-year payback (i.e., cost-recovery) periods compared with solar photovoltaic (PV) systems which require a 6- to 10-year payback.  

Energy consumption is influenced by numerous building features; these can be identified and opportunities for efficiency improvements assessed whether the building is a sanctuary or one of ancillary use such as a school or multi-purpose facility.  The building “envelop” itself (insulation, air circulation, window quality) as well as all systems within (heating, ventilating & air conditioning (HVAC); lighting; water heating; and office and kitchen equipment) can provide opportunities for improved efficiency.  In some cases, rebates for specific upgrades are available; their availability can be checked by checking with your local utility.

Energy Audits

A logical start to understand a building’s energy use is an audit.  Unfortunately, this logical and appropriate first step is perhaps the most confusing and misunderstood as all audits are not equal.  The following table summarizes our perspective of alternatives.  The table reflects differing levels of comprehensiveness identified by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE).

“Free” audits are often available (typically Benchmark or Level 1 quality), but these provide the least actionable information.  Exceptions may exist if a local utility or non-profit is funded to provide a more thorough audit at reduced or no cost to the recipient. The more comprehensive audits can cost hundreds of dollars.  An auditor’s affiliation with the Building Performance Institute (BPI) or ASHRE should be a plus.  Home Energy Rating System (HERS)-qualified auditors can be useful if your building(s) are not much more complex than a standard residential structure.

Least ComprehensiveBenchmarkNo on-site review; comparison of energy bills with like buildingsLocal benchmark data is most useful, but least likely available*.  Average national data is available, but of marginal usefulness for each region.
ASHRE Level 1 Audit or equivalentBenchmark and walk-throughWalk-through to identify obvious inefficiencies
   ASHRE Level 2 Audit or equivalentLevel 1 plus identification of consumption by end-use to identify the greatest opportunities for improved efficiencyMay also review utility rates; test equipment may be utilized. Possible benefits of new lighting, HVAC equipment and/or EnergyStar appliances.
Most ComprehensiveASHRE Level 3 Audit or equivalentLevel 2 plus cost analysis of possible changes for investment decisions.Detailed cost analysis permits consideration of which investments have more rapid paybacks.

 * This is changing as more cities and states undertake Benchmarking and Transparency (B&T) programs. There are
    over 2 dozen such programs at this time (2021).

Interior of UCC – Urbandale following lighting retrofit.

Energy End Uses

Our experience and national data suggest HVAC, lighting, and appliances (cooking and refrigeration) are the greatest energy end-uses in houses of worship. The U.S. Energy Information Agency (EIA) 2012 Commercial Building Energy Consumption Survey (CBECS) reports for Religious Worship Buildings:

  • 60% of energy (consumption, not cost) is used for heating, cooling and ventilating.
  • 8% is used for cooking and refrigeration
  • 5% is used for lighting
  • 27% is used for office equipment and (unidentified) “other.”

(Source:  Table E1, https://www.eia.gov/consumption/commercial/data/2012/index.php?view=microdata ;

Comparable 2018 Survey data will not be available until Spring 2022)

It’s appropriate to start with a review of HVAC systems, air circulation and building weatherization.  We reference the discussion above about using trained professionals.  Regrettably, in our experience, many HVAC contractors claim to be “energy experts,” but their finished work is of highly variable quality.  Checking on-line references like YELP is suggested if you choose a contractor to conduct the analysis. 

Weatherization, especially insulation, weather-stripping, and better insulated windows and doors with double paned glass, can be high return investments. Fixing cracks around doors and windows is a low-cost solution which could save you hundreds of dollars in energy costs. First Lutheran Church in Decorah, IA made changes to target these issues and saw immediate results. They had already replaced all of their windows and doors to be energy efficient but after an energy audit they found they were still losing 48% of their heat through the walls and 18% through the attic, both due to lack of insulation. Addressing this contributed to energy cost savings in the first year. To learn more about what all they did see https://iowaipl.org/first-lutheran-decorah/. Making these changes along with other items, some mentioned below, helped them cut their energy costs by 49%.

One item First Lutheran Church addressed was their HVAC, but there are also some smaller things you can do to help efficiency in this area. You want to keep your current HVAC system as energy efficient as possible, no matter its age or type. Regular maintenance including changing filters and cleaning coils has been known to reduce energy use by 5%. Numerous congregations have reported savings with simple improvements in sensors and thermostats!  The percentage of congregations that have installed Programmable Thermostats (26%) is the same as the percentage installed in all types of commercial and public-use buildings (2018 CBECS).

Changes to cooking and refrigeration typically involve replacements with modern EnergyStar-rated appliances. An audit that identifies their consumption and associated utility cost will help identify the payback period for such a change as well as the carbon emission reduction benefits. Other impactful changes you can make are keeping freezers and refrigerators well maintained, with condensers/coils clean and unclogged, and keeping them relatively full. You can do this by adding jugs of water which fills the empty space with something that helps keep the temperature down thus allowing the freezers and refrigerators to run more efficiently.

Most buildings have centralized hot water heaters that distribute the water to the kitchen and the restrooms throughout the building. To maximize existing systems, consider wrapping any hot water heater that is more than 5 years old with an insulating blanket. You also want to insulate the first 3 feet of the output pipe. This is where the most heat is lost on all ages of water heaters. Decentralizing the hot water makes the largest impact because the shorter the distance the hot water has to travel, the less heatit loses. Changing to on-demand water heaters, especially for restrooms that uses less water, save energy because you are then not paying to heat a large tank of water that loses heat as it sits.

The national data suggests lighting is 5% of total energy use, though it is likely a much larger share of a congregation’s electric bill (as compared with heating oil or natural gas).  Studies conducted by IPL in the San Francisco Bay Area suggest lighting is a far more significant share of utility costs than this national survey indicates.  (Perhaps in part due to a moderate climate and reduced HVAC-related charges.)  Light Emitting Diodes (LEDs) are a low-consumption type of lighting that has been implemented by numerous IPL Cool Congregation awardees in recent years. Indeed, according to the 2018 CBECS, 51% of congregations have adopted some level of LED lighting compared with only 44% of all commercial!  Unfortunately, congregations have been slightly less pro-active adopting other cost-reduction measures such as Occupancy Sensors (12% versus 17% of commercial building types). In this case, electrical contractors should be able to accurately identify the cost and cost-savings of a change in lighting. While lighting may represent a small share of the total electric bill, it is likely the one area where low-cost and immediate benefits are realized. 

If you are looking at how to get started funding larger projects, many religious institutions have established building funds that provide loans for capital improvement projects, including energy efficiency measures. Check with your greater faith-based organization or your local IPL chapter to see if there is one for your congregation. Some examples are the Mission Investment Fund of the ELCA (mif.elca.org), UCC Cornerstone Fund (cornerstonefund.org), Disciples Church Extension Fund (disciplescef.org), and the Presbyterian Church Investment & Loan Program (pilp.pcusa.org). They vary on loan terms, project types, etc. but all provide loans to their prospective religious bodies and can be resources to allow you to start your energy saving projects right away.

Yet, changes need not be complex.  Examples of actions congregations have taken are available on IPL’s Cool Congregation website at https://www.coolcongregations.org/the-challenge/meet-previous-winners/  Some congregations have indeed been able to build entire new houses of worship with a zero net energy target.  Conversely, projects can be as simple as congregants building thermal window inserts to help winter-weatherize their own house of worship, with added units provided to low-income neighbors. There is likely a carbon-reduction (and cost savings) opportunity for most congregations waiting to be found.


Anne Gerrietts is a freelance Church Building Consultant who advises congregations as they discerned building needs with a focus on their ministry. She holds a degree in Civil Engineering and an accreditation as a LEED AP along with being a life-long Lutheran. She previously spent 12 years working for the Mission Investment Fund of the ELCA as a church building consultant. You can reach her on LinkedIn or at amgerrietts@outlook.com.

Gerald Bernstein is a volunteer at IPL’s office in Oakland, CA.  Following 30 years providing engineering consulting services to companies in the transportation and energy industries, he spent 10 years at City College of San Francisco initiating solar PV installer courses, adding energy efficiency curriculum to construction courses, and supporting hybrid and EV additions to the Automotive Technology curriculum. He has degrees in Aeronautical and Civil Engineering.

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