To save money in this area you need to know and control several things:
- What the temperature is when it comes into the room
- How long the conditioned air is on
- Where conditioned air leaves the room
- To control the temperature for the air coming into a room, I set all the thermostats at
- Occupied Heat (people using the room during heating season), 68 Fahrenheit
- Unoccupied Heat (the room not used during the heating season), 60
- Occupied Air Conditioning, 74
- Unoccupied Air Conditioning, 80
- You don't want to set the unoccupied temperature too high or low - that will cause the unit to have to work extra hard to get to the occupied temperature when it is called for. The occupied temps are just inside the "uncomfortable" zone - the temps are still comfortable but because they are at the limit, they save large amounts of money than if they were right in the middle of the comfort zone. Frankly, there is no comfort zone that meets everyone's needs - I hit the edges of the range and then rely on people to dress accordingly, but they still complain. Keeping your building temps within these ranges will save your budget thousands of dollars - I highly encourage you to do this.
- To control how long the conditioned air comes into the room, there are several cool pieces of technology
- Programable thermostats
- These are great because they can turn a unit on and off when the room is being used according to the program that is keyed into it. This ensures that the units are running only when someone has told the unit to run. Most programmable units have some sort of temporary override button or control. The override is to ensure that when there is an unscheduled meeting, the unit can be turned on in order to get the room to the occupied temp (whether heat or A/C).
- The bad news about programmable thermostats is that they rely on humans. Humans have a tendency to want to mess around with thermostats. I've found thermostats with the date and time changed (which plays havoc with the schedule that was originally programmed). I've also seen thermostats with the programmed temp and run times completely changed. And it doesn't matter if the thermostat is behind a locked casing or a locked screen, that is just a challenge to some people to figure out how. The human factor is pretty frustrating.
- The latest piece of technology which I plan to try in a few places pretty soon is a thermostat with a motion sensor. The idea is that when the motion sensor comes on due to movement, it turns on the thermostat which in turn may (or may not) call for the unit to bring the room to an occupied temp.
- There are several good things about this:
- You only need to program the thermostat (these motion sensor stats are also programmable) for the times of the week when people will definitely be in the room. The rest of the week the unit will turn itself on when it senses motion in the room.
- The thermostat will keep the unit on so long as movement is sensed and when it comes on, it will stay on for 15-20 minutes (whatever is programmed when it is setup).
- This device completely eliminates the human error element and that is a huge relief.
- You will see immediate savings because the unit is running only when it needs to run - not when the room is empty (even though a meeting was scheduled).
- There are several bad things (or perhaps I should say, "unknown things"):
- The unit will turn on whenever a custodian comes into the room to get one chair or when kids are playing "hide and seek" in the room.
- If the unit turns on and off several times a day, it can shorten the life of the unit by several months or even years. That can be mitigated by lengthening the "on" time for the unit to 20-30 minutes but that will also decrease the savings.
- These thermostats are not cheap. And, if the thermostat controls temps in several rooms, you'll need to install a sensor in each major room controlled by the stat so that if someone enters a room, that sensor will "see" the person and turn on the unit (even though the actual motion sensor thermostat is a couple of rooms away). Installing the extra sensors is not cheap either.
- There are only just so many places conditioned air can leave a room
- Ceiling - most commercial buildings have drop ceilings for the convenience of accessing equipment and running wires without destroying a hard ceiling. However, some amount of conditioned air is lost above the drop ceiling. The good news is that it is not that much and it is usually is a layer of hot air (because hot air rises)
- Doors - every time a door is opened, air rushes out (or in). If the room's thermostat is in occupied mode, then it is a great idea to keep doors closed. Hallways may or may not have conditioned air but hallways, by definition, lead to doors that go to the outside.
- Walls - yes, walls leak air. If you can, insulate them in order to keep conditioned air inside the room. Insulating a wall after it is built is not cheap and it is very messy. But it can lead to energy savings.
- Windows - this is probably the place in a room where conditioned air is lost the fastest. Windows leak like a sieve. I highly encourage you to get double-paned, energy efficient windows in all your openings.
- That is a huge expense to most churches - let me suggest that you begin phasing in the windows over a 5 or 10 year time period. Divide the church up into 5 or 10 sections and begin replacing windows one section at at time. Doing it in phases will not consume your maintenance budget in one year but spread the cost over several years.
- The best time to do all energy efficiencies, is at the beginning of your budget year. If you don't have a capital budget (and most churches don't), then spend the money in the first month of your fiscal year. Charge some of the expense to your maintenance budget and the other part to your utility budget (because your utility budget will decrease that year due to energy savings).
- One way to fund capital needs, is to take any "leftover" budget money at the end of the fiscal year and put that money into a fund to pay for capital items. I'll explain this concept in another post - it's one of my favorite ways to get things paid for without hurting the budget.
There are significant and real savings is in controlling the temperature in the building.