I'm trying to reduce my church's utility bill.

Our HVAC works in four zones of 1500 square feet each. Two of the zones are the sanctuary, two are offices. We get a bill for each. The sanctuary zones cost us around $250 each, the office zones $130. They keep the air on 68 except Saturday night they turn it to 60 so that it will be cooler for Sunday. It's always freezing cold when the building is in light use, and burning up hot when it's full of people.

It's a storefront-type building with acoustical tile ceilings that are 10' in most places, 8' in the offices, and 15' in the tallest part of the sanctuary.

Any suggestions?

I'm trying to reduce my church's utility bill.

Our HVAC works in four zones of 1500 square feet each. Two of the zones are the sanctuary, two are offices. We get a bill for each. The sanctuary zones cost us around $250 each, the office zones $130. They keep the air on 68 except Saturday night they turn it to 60 so that it will be cooler for Sunday. It's always freezing cold when the building is in light use, and burning up hot when it's full of people.

It's a storefront-type building with acoustical tile ceilings that are 10' in most places, 8' in the offices, and 15' in the tallest part of the sanctuary.

Any suggestions?
Change SP 68 to 74 and put in some fans, you have drop ceiling? Put insulation on top

Not all is equal, I'm sure. We don't know age, efficiencies, or size of the equipment. Four separate A/C units controlled by 4 separate thermostats? Is the equipment properly maintained? Heat load, sun exposer, and actual cubic footage for each zone appears to be differing from offices to santuary. Insulation as stated above can help. I'm not so sure of the fans though. If the cielings are quite high in the sanctuary, it may be better to let the heat statusfy up there.

For another 68 is quite a cool temperature for most dwellings, if I where at home I would have to put a wool blanket on, in the winter time most customers would complain about such a cool home.

And lastly, in a unique situation such as a church, where the occupancy goes from 12 to 1200, staged equipment is the solution. First stage will keep the area cool and dehumidified using as little energy as possible, then when the demand is greater, the second stage can come on and maintain what the first stage had begun.

Best of luck

First let me say I agree with the above posts. It sounds as though the sanctuary air conditioning units do not keep up with the load in the building during Sunday services and some one is trying to compensate by turning the thermostats down to 60 degrees, this is very inefficient as well as detrimental to the a/c equipment and may freeze up the evaporator coil thus reducing its capacity due to restricting the air flow. You should never set the cooling set point below 70 degrees unless it especially designed to cool at lower temperatures such as in a computer room.
I have a suggestion, if you could install motor operated dampers in the office a/c duct work and divert this air to the sanctuary on Sundays to help carry the load you could save money by operating the a/c equipment at a more comfortable setting (74 degrees or higher) instead of running it continuously when it is unoccupided. This may not be possible but it's a thought. Good luck, Mike

I'm sorry, I should have phrased my question better.

We're not in a position to invest any money into the HVAC system.

How can we best OPERATE it to save on our utility bills, and still be comfortable for services Sunday?

I did install four ceiling fans in the sanctuary and they help greatly.

The sanctuary seats about 200, however it was originally a retail space, and while it is enough square feet for 200 people, I'm sure the HVAC and air handling were not installed with that in mind.

Thanks for all the answers.

In response to acetc, you're saying turning it down to 60 can damage it, should we leave it set to a lower temperature throughout the week?

Turning a thermostat down to 60 degrees can cause the evaporator coil to freeze if the room temperature gets below 70 ,because 69 degrees is the number that the freezing starts to take place, once the coil ices over it blocks the air flow, but what happens in the system is the refrigerant does not change state completely and will return to the compressor as a saturated vapor meaning it is part liquid and part vapor, this saturated vapor can chase the oil out of the compressor causing it to run without lubrication or can wipe out the valves in the compressor because a compressor cannot pump liquid.
Hope this is helpful, Mike

Ok, so what should we do then?

With out spending money the best thing you can do is to set thermostat to come on about 2 hours before the Sunday services and set to 74 degrees, then set thermostat to 80 degrees during unoccupied periods so that the area does not get so hot that the equipment can't pull it down to occupied temperature when you need it . You my friend are looking at a fine ballancing act, between efficiency and comfort. Mike

That would be way too hot. When we have it set to 72-75, it still ends up 90 when people fill in.

Wouldn't it be better to leave it on one temperature all week?

Last night we set it to 68, once service got underway it was still close to 90. AND it was cool outside today, in the 60s I believe. When I checked the thermostats during service, they had cranked them back down to 60.

Pictures are worth many words.

http://www.bandwidthcrazy.com/mr_spiffy/church.jpg
http://www.bandwidthcrazy.com/mr_spiffy/church3.jpg
http://www.bandwidthcrazy.com/mr_spiffy/church4.jpg
http://www.bandwidthcrazy.com/mr_spiffy/church8.jpg

It appears there is a lack of supply registers for such a large number of people, without spending any money there is not much you can do, Mike

So I guess my question is, are we better off leaving it on a lower temperature, or keeping it on a comfortable temperature throughout the week and lowering it Saturday night?

Also is it best to keep the doors between the different areas closed, or open?