Question, what is the biggest factor on a building’s energy use? Is it the HVAC, lighting, building envelope, or behavior?
Of course the title gave it away, but If you answered behavior you are correct.
The following practices that should be considered when operating your HVAC.
- Zoning. As mentioned in the above examples zoning offers a great way to maximize energy-efficiency. The ideal position is to only condition the zones that are occupied, thus the importance of paralleling the church calendar with the HVAC controls.
- Hours of operation. This too is a very important factor in behavior. If your church or zone is only occupied for two hours a day, the area should only be conditioned during those occupied hours. Of course there is some contingency built in because it takes a certain period of time for areas to reach a desired temperature set point.
- Temperature set point. According to the EPA a facility can save 1.5% on the HVAC portion of their utility bill for every degree they change. Example if your average church temperature setpoint is 72° and you adjust to 74°, then the church will see A 3% savings on the HVAC portion of their utility bills.
- Setback mode. The most efficient mode for any HVAC system is off. However certain systems or building envelope will not allow a system to be turned off. For example in colder environments with steam or forced hot water, flow rates are important so pipes do not freeze or burst. In other areas building envelopes are not strong enough to maintain desired temperatures. In these cases we recommend an aggressive set back temperature that match the corresponding seasons.
- Outside air. Per code there must be a certain amount of an outside air that comes into the building during occupied hours. Most of the facilities allow for this practice, however most facilities do not adjust for unoccupied hours. If doable, outside air damper’s should be closed during non-occupied hours. Conditioning outside air is a very expensive habit. However energy can be saved if the outside air damper’s are closed during unoccupied hours.
I have mentioned this in past articles, but it is worth mentioning again, “According to the environmental protection agency, 30 percent of the energy we use today is used inefficiently”. We might have the most energy efficient chiller or boiler, have efficient LED lighting, have triple pane windows, and still be using 30 percent more energy than needed.
There is a common misconception that when installing new equipment, that efficiency takes care of itself. This is not the case. Sure a 17 SEER rooftop unit is much more efficient than a 30-year-old unit. However, if the owner of the 30 year old unit controls the use whereby the owner of the new unit does not control use, the older unit will use less energy. This makes sense.
The goal of any energy management program should be to hug occupancy. Basically I mean that lighting, heating, cooling, plug load, and others should be running in the most efficient manner possible only when the building is occupied. When the building is unoccupied the facility should be in it’s setback or off position.
I would like to focus this article on the importance of scheduling, zoning, and set back temperatures related to heating ventilation and air-conditioning.
It is extremely important to parallel HVAC use to church calendars.
Let me give you an example, say you walk in to church-A and the church has 10 different HVAC zones.
Meaning the church has the ability to independently control separate zones.
Zone one operates at a different temperature set point then zone 10. However instead of maximizing these different zones, the church turns on all 10 zones for 12 hours at 72 degrees regardless of the occupied zone.
This is a very expensive habit. However, say we walk into church-B. We might find a church that is maximizing their system. For example the church is occupied in zones one, two and three on Monday, Wednesday and Friday. Opposed to turning on all 10 zones, the church only conditions the occupied zones for the occupied time (4 hours) while keeping the other seven zones off or in set back mode. We see this type of practice every day during our energy audits, and as mentioned it is an expensive behavior-related practice.
Church-A, given the example, might spend $10,000 a month on the HVAC portion of their utility bills.
On the other hand church-B, might spend $5000 on the HVAC portion of their utility bill.
There are a number of standards and practices that I am glossing over, but the concept is very real and very doable. This is why I believe a church facility manager is one of the most important positions in a medium to large size church.
The facility manager is able to oversee practices such as zoning, which more than pays for itself.
If you have any related questions we highly recommend you consult with your energy management firm, or feel free to reach me at [email protected]