Church HVAC Efficiency


At this point, you may have read the past two blog posts:

  1. Church Energy Improvements, Part One
  2. Continued Church Energy Improvements

Those posts were written about my home church in Georgia.  From the previous articles, you probably already know that the Broad Street church has along way to go in terms of facilities efficiency.

In the continuation of the series, we’re going to examine the HVAC efficiency using the current heating/cooling schedules of the facility.

Church HVAC Efficiency

We will presume that all components of the HVAC systems of the building are in a proper working order. In practice we know this is a false presumption. The “new” units aren’t well-maintained and the “old” units are in bad shape.

In a recent examination of thermostats in the “new” section of the building, I found that they’d never been set. For four years, this building has heated/cooled itself on the priorities of never-before-adjusted thermostats. The whimsical wants and wishes of church members have resulted in cooler/warmer spaces for weird or long periods of time.

Let’s give some breakdown of the thermostatic control of the building.

  1. Old Building
    1. Auditorium: There are two 5+1+1 thermostats–one for each side of the auditorium. The space is gas heated/electrically cooled. The 2006 programmable thermostats (Honeywells) only begin heating/cooling at the specified time and do not take into account the amount of time required to heat/cool the space to the desired temp.
    2. Balcony: There is one manually-operated thermostat for the balcony space. A separate HVAC unit to itself, that unit is really only required in the summer when hot air (rising) has turned the balcony into a comfortably-seated oven. (It should be noted that black slate (yes, real slate!) shingles are in use on top of the building.)
    3. Basement: Once containing the classroom, kitchen, and fellowshipping spaces of the building, the basement now is basically underused and underappreciated space waiting for something fantastic to happen. There is one 7-day programmable thermostat for the entire, relatively unused, space.
  2. New Building
    1. Foyer: There is one 5+2 programmable thermostat for a large hall/foyer space.
    2. Room 105: A multi-purpose room. There is one 5+2 programmable thermostat for that space which is often used for community events and meetings. It seats about 35 people comfortably.
    3. Gymnasium: There are three 5+2 programmable thermostats for the gymnasium space
    4. Kitchen: There is one 5+2 programmable thermostat for the kitchen. There are lots of heavy-duty appliances running in there, so that space is automatically warm.
    5. Office space: There is one 5+2 programmable thermostat for the office space. This space is well-used all week long.
    6. Upstairs: There are three 5+2 programmable thermostats that ultimately control zones which include hallways, bathrooms, and classrooms.

The thermostats in the new section of the building have the option to transition automatically from heat to/from cool. I’ve left this setting as manually adjust now in case of seasons of unusual warmth (we just had some 80-degree January, 2013 days) or unusual coolness. All thermostats EXCEPT 1-3 (old) and 2-5 (new) have had schedules reset. Thermostat 1-3 is under close supervision by conscientious office staff–more conscientious than the schedules would permit. Thermostat 2-5 has remained unset simply because of humidity controls for the basement. However, thermostat 2-5 will soon enjoy a program.

Several dilemmas occur when trying to set a temperature policy. For instance, our church has a Wednesday evening service. But, if we set the auditorium controls to be 68/75 (heat/AC) for those times (6:30-7:30 PM), that means that Monday, Tuesday, Thursday, and Friday also unnecessarily enjoy those temperatures. Similarly, the gymnasium houses our Wed. evening meals and congregational Sunday Dinners (lunch on Sundays) on the third Sunday of each month. The Wednesday night temperature problem is the same as in the auditorium and the Sunday settings mimic an identical problem. The classrooms also have the same Wednesday woes. The solution: someone goes about and manually adjusts the temperatures as they would have before any temperature was set. This is certainly not easier, but it is less costly.

The kitchen is its own temperature schedule. With multiple appliances running 24/7 and a gas pilot light, the kitchen is cozy–even on cold days. The “empty” temperature setting reflects that artificial heat. The gymnasium remains on an “empty” schedule 24/7. If people wish to adjust temperatures, they may do so in unison between all three thermostats. The foyer space presets to the “in-use” setting only on Sunday mornings for 9:30 am-10:30. The upstairs classroom/hall/bathroom spaces all are set to be “in-use” from 10:30-11:30. All other times are “empty”. The auditorium heats/cools from 8:30 (to warm up the space) until 11:30. Room 105 is conditioned from 10:30-11:30 on Sunday mornings only. Any other changes are fine. The program will revert to preset temperatures at the scheduled shift change.

Currently, the “empty” temperature settings are 58/83 (heat/AC). We will readjust the empty heat setting to be 55 and the empty AC setting to be 85. The “in-use” settings are 68 and 75. Although this does not follow the guidelines as set by DeVries (2002), it does adhere more strictly to the AASHE guidelines for academic buildings.


So far, we’ve only locked the three thermostats in the gymnasium and have requested that anyone changing the thermostat settings NOT hit the “hold” button. The schedules are spread out throughout the day so that anyone changing them may have a few hours of relative comfort–we don’t want them continually changing the temp.


DeVries, S. (2002). Energy conservation reference and management guide for churches. Lansing, MI: Michigan Energy Office. Retrieved from