Air conditioning

[hmhyde]

After begging for air conditioning/ heat for years, the school has finally agreed to put it in, but seeing as the head of maintenance originally wanted to put in a loud exhaust system instead, I'm a little wary of what they might try to put in on the cheap, any ideas of what to look for?

 

[museav]

After begging for air conditioning/ heat for years, the school has finally agreed to put it in, but seeing as the head of maintenance originally wanted to put in a loud exhaust system instead, I'm a little wary of what they might try to put in on the cheap, any ideas of what to look for?

A Mechanical Engineer who is familiar with designing systems for peforming arts venues and that either has in-house acoustical expertise or that uses a qualified acoustical consultant. And that is not an idealized approach, a Mechanical Engineer will likely have to be involved in the design of the system and unless they have the expertise internally then for this type of application somebody needs to be addressing the acoustical aspects, even if just to review what is planned, point out potential concerns and offer general recommendations.

If you do not approach it that way then your concerns may be well founded as there will be code compliance factors that will be involved in the mechanical design while there are only recommendations regarding acoustics. Unless someone is there to address and fight for the acoustical considerations then if budget constraints or Value Engineering become a factor the impact on acoustics may not be much of a consideration in the information presented or the decisions made.

This reminded me of a project years ago when I was with a MEP consulting firm and an Owner hired us to provide acoustical consulting for a competing Mechanical Engineer they had selected for the mechanical system design work. What was interesting is that we had bid on and lost the mechanical consulting portion of the work to that firm because our fee was $1,500 higher - and included the same acoustical consulting services for which they then ended paying us $3,000. One example of when looking at the low bid for individual portions of the work actually resulted in a greater overall cost.


Added: I'm avoiding getting into specifics as there are likely some 'big picture' aspects that will greatly impact everything else. Things such as the condition and design of any existing heating and ventilation systems, whether the school has a central plant with sufficient capacity to also support the theater, whether the changes may entail incorporating new energy codes that in turn affect the existing installation, what the existing HVAC controls system supports and so on.

However, there may be a few aspects for you to think about such as whether there are areas such as shops or booths that may operate different hours than the auditorium and thus need to be controlled separately, whether there are spaces such as shops or paint booths that may require special ventilation, and whether there are equipment spaces or similar where the equipment in them represents significant heat loads and/or that require certain temperature or humidity conditions. This is focusing more on defining the needs and goals than the solutions, but such considerations could have an impact on the solutions developed or may have to be coordianted with the limitations of what can be done.

 

[tdeater]

the overall design idea they used on our theater was high volume, low velocity (aka move a lot of air slowly) Get the equipment isolated from the space. Compressors and such can add a lot of vibration to things. In our space, every piece of mechanical equipment with a fan or spinning motor in it has vibration isolation on it's mounting and duct work/piping. Also remember the heat load of an audience and lights. What is good enough to cool the space during the day, or rehearsal times may not be close once you put a few hundred heaters, aka audience in the space.

 

[FMEng]

I agree with everything that Brad said. This is not a situation where contractors can be asked to do a design-bid process. You might get cold air that way, along with excessive amounts of noise that renders the space useless when it is running. This requires a mechanical engineer working together with an acoustical engineer to be successful.

Then, the engineer's completed design can be put through the competitive bid process. Not only will you get a system that'll work properly, but all of the bids will be for comparable systems if they meet the specifications.

 

[marmer]

Another thing to watch out for is supply duct location and air speed on stage. Depending on what kind of performances you present, you may want a lot of air flow (for costume dramas) or little air flow (for classical music and lectures). If audience members or performers feel a lot of air movement they are likely to complain about being either too warm or too cold. If it's really fast or in the wrong place it will blow their sheet music or lecture notes away. Some big halls (like mine) can't catch up with cooling if they get too warm from large audiences plus lots of light on stage. You'll have to plan for pre-cooling.

 

[Lambda]

I can tell you two things to watch out for, because they are two things that were done wrong in our theater.
Placement of ducts, for one. The way our HVAC system is installed, a meter-square duct runs right through the middle of the flyspace, rendering that entire area unusable in terms of rigging.
Secondly, placement of intake and output vents. In our space, the intake vent is backstage. The output vents are FOH. That creates issues when the curtain is closed.
One thing that is convenient about our system is that it is separate from the school's central furnaces. You may want this, because if your school is anything like mine, then any time it isn't arctic freezing the furnaces are likely shut down.

 

[museav]

The last couple of posts indicate why it is important to get parties specifically familiar with theatre applications, a factor that can be challenging if the work is approached as a 'qualified low bid' public bid as many of those involved do not understand the implications and thus may trivialize the importance of such directly relevant knowledge and experience.

 

[hmhyde]

Thank you all so much, this has been quite informative! Hopefully now I'll be able to negotiate something that is more beneficial to the space

 

[Robert]

You will likely have smoke detectors installed in the return air ducts and the supply lines from the blower. This may affect your ability to use smoke effects on future productions. A system designed with by-pass switches and a procedure for monitoring them can help. This typically involes a fire-watch which will cost money.

 

[tdeater]

A bypass switch is something we have in place for our theater. it works well. We have a Simplex system. We where able to have Simplex program in a psudo point in the system that disables all of the ductwork detectors related to the theater for 3 hours. It does generate trouble points in the system, so we have to call our alarm company before we do it, and we do task a supervisor, usually myself, to the firewatch duty. It does not disable any other detectors or anythign else, only theater related smoke sensors. Heat sensors are still active.

To prevent people from messing with that bypass, it is password protected, and only supervisors have access to that password. (although it is such a pain to navigate the menus in the simplex system that I doubt anyone would be able to figure it out with a password)

 

[marmer]

Your AHJ is going to have an opinion about bypassing venue duct detectors, especially during performances. If they let you do it at all it may well require actually having a firefighter or fire marshal present for the firewatch. It does for us here in Houston.