Indoor Air Temperature

[Darin Steffl]

What do you guys heat and cool your indoors to?

In winter we heat to 69° and cool to 70° in the summer but our humidity is bad at 60-70% in the summer even with AC running so we're going to get a big dehumidifier and see if we can keep it under 50% and bump up cooling temps to 72-73

Anyone else have a humidity issue in the warmer months? What do you do to address it?

We have a very leaky building that we're working to fix and seal up with new roof and siding projects. We have a crawl space under our main auditorium that I'm sure gets humid too. We have two sump pumps already that are working.

An old article about AMC says they heat to 70 and cool to 74 with local managers have minor adjustments available to them.

[James Wyrembelski]

68 in winter & 70 in summer.

I'm not sure how yours is constructed but ours being a cinder block building with most of the auditorium sloping below ground level it stays pretty cool in the winter without much help from the AC. The floor is solid concrete as well so I'm sure that helps.

Michigan is a swamp in summer and humidity does not seem to be an issue in the auditorium at all. The lobby......different story. It's not air conditioned so we suffer after the show starts, but the guests are cool.

Much harder to heat the auditorium than cool for sure. I have yet to turn the AC on and we've already had a few 90+ degree days. It stays about 68-70 until June.

We also have 4 ceiling fans which vastly improve the heating quality in winter. They stay off in summer.

I will add that particularly long, humid spells I'll drop the temp down to 68-69 to help cut any humidity that may creep in.

[Marcel Birgelen]

Over the years, I've seen that keeping the humidity down is often more beneficial than keeping the temperature down. People will dress differently on warm days than on cold days, so you don't need to cool down the room to 19C/66F to keep most of them comfortable.

What I've often heard is that people start to complain about all kinds of "airco allergies" when the temperature gradient is too big between the inside and outside. They suddenly start to develop a cough and whatnot, but if you keep that reasonable and manage to keep the humidity down, you get almost no complaints about the temperature or "airco allergies".

[Buck Wilson]

68/72 here. We definitely have humidity problems in summer. Theater was built on land with kind of a mild spring fed swampiness to it... There have been some summers where water seeps up from the floor through the cracks in the concrete even. It doesn't help that the air returns are on the ceiling instead of ducted down to floor level to pull up the dense humid air. If I were to spec my own theater, I'd use variable speed hvac equipment to maximize dehumidification and duct the returns down to floor level to get proper circulation.

You may look into crawl space encapsulation or at least a vapor barrier over the soil to dramatically cut down on the moisture intrusion. Helps air quality too, less dust/mold spores/etc

[Mike Blakesley]

We have separate systems for heating and AC so the trick is to make sure to turn the heat off when it warms up so they are not competing with each other. It does get kind of humid here in the summer, but for the most part we have a dry climate. I keep the thermostat at 68 for the heat and somewhere in the mid 70s for the AC.

If the outside temp gets into the mid 70s, it is trickier -- too much AC freezes people, and too little, they start sweating. So if it is between 65 and 75 I'll turn on the fan only, not the actual AC just to keep air moving.

[Randy Stankey]

It really bugs me when people won't understand that it takes time to heat or cool a building.

There have been several times when I have been asked to change the temperature when I know that the system is running at maximum already.
I would have already noticed that the temperature was off and would have changed the settings or a quick check tells me so.

I tell them, "Yes, the system is already running at maximum." Sometimes, I'll fib and go check the temperature and, maybe, fiddle with the controls, just to make it look good.

Still, fifteen minutes later, they are complaining again. I don't know how to explain, nicely, that a theater has as much as 125,000 cubic feet of air that all needs to be heated or cooled.

[Mark Lane]

We have issues with humidity here in Mid-Michigan. We have two dehumidifiers to help reduce the issues. We have two air condition units located at the top of the theater since the cold air will travel downwards and a heating unit located at the bottom of the theater since heat raises. This system makes the seating area more comfortable before the auditorium reaching the ideal temp.
I can control the temp with an app on my phone so I can check and adjust the humidity and temp while not at the theater.

One of our dehumidifiers crapped out on us this weekend.

[Marcel Birgelen]

With cooling, you can't do much more than cool the air that flows through the auditorium, but I wonder if it would be more efficient to employ some kind of infrared heating built into the ceiling to warm people up. That would also be much speedier and probably more energy efficient than warming up the entire building.

[Randy Stankey]

Some buildings use heat recovery units as part of their HVAC to pre-warm incoming air in a heat exchanger warmed by exhausted air.

At one place where I worked, we had an incident where people were complaining that it was cold. The heating unit was a two-stage system and both stages were already running but the building wasn't getting warm fast enough.

I called the building engineer who said that it was unexpectedly cold outside, meaning that the cold, incoming air was making the heating units work harder. He came over and made an adjustment to the heat recovery unit and, within the hour, the building was well on the way to warming up.

That only works on newer buildings with more modern HVAC systems, however.

In an older building where I once worked, the system used a steam coil to preheat incoming air. (The building was heated by municipal steam.)
There are some downsides to that. First, it takes more energy to heat incoming air but, I suppose, if you are using municipal steam, the extra cost might not add up to much. The worst problem is that, in a steam coil that's essentially being cooled by cold, wintry air, the steam quickly condenses back to water and, if that water freezes, the coil will explode the next time the system tries to push hot steam through an ice-laden pipe.

I was present for one of those incidents and I saw the aftermath. It looked like a bomb went off inside the ductwork!

In a way of thinking about it, a bomb DID go off inside the duct but, technically, it would have been a BLEVE (Boiling Liquid Expanding Vapor Explosion) which can be even worse than a traditional explosion.

For reference, see the Mythbusters episode on water heater explosions:
https://youtu.be/rGWmONHipVo