Make your mechanical systems do the right thing
In building or renovating a performing-arts venue, HVAC (heating, ventilation, and air-conditioning) and sprinkler systems can be problematic if not carefully planned for and watched throughout construction to make sure that changes, for whatever reason, don't have a negative impact on your needs for future productions. Working out space for sound cables, electrics cables, DMX, Ethernet, and expansion in the future must be done while saving enough space for all the mechanicals needed. Why does it seem like everyone is always fighting for space when it looks like there was enough crucial space on stage and in the grid, and enough front-of-house lighting positions during the design phase?
Sprinkler pipes are part of the mechanical engineer's work, including water, sprinklers, sewage, and steam (if that's the heat source). In New York, you can buy steam directly from Con Ed. This can be an easy space-saving method of heating without needing a large heating plant in your building, but that's not always the case in some cities. I'm sure you've been to theatres and other entertainment venues where you ask: Why is there a column there, why is there a catwalk there, why is there an air-conditioning duct there, or why isn't the stage air conditioned? Proper planning in renovating or building a new performance space can help avoid these problems.
In the meantime, your acoustician must keep track of sound isolation and other acoustic requirements for performance and rehearsal spaces. I'm sure you've been in buildings that have banging radiators, blowing air noise, and breezy spaces. To achieve a quiet space, you want to use a forced-air system that will deliver low-velocity and high-volume air, which generally means very large ducts. During schematic and design phases of any renovation or creation of a new space, the sprinklers and the HVAC ducts must be given ample space.
Asif Syed, a partner at AKF Engineers, is an engineer who worked with me on the renovation of the Biltmore Theatre in NYC. When it comes to air conditioning, he presents the pros and cons of displacement and conventional systems: “Displacement is supply from the bottom and return from the top, while conventional is supply from the top and return from the bottom. Displacement is useful in theatres,” he says. The difference is in the temperature between the two systems, as conventional supplies 55° air, and with displacement, you supply 65° air. The lights in a theatre also play an important role. “In a conventional system, you have to cool the air past the lights; in the displacement system, the air in the ceiling does not matter because you're cooling from below,” Syed points out.
“There are a number of ways to use a displacement system,” he continues. “You can put it in the rise of each step, or you can blow it up from the floor. Some seats are built so that you can blow it out the standard of this seat. Or you could put it in front of each seat more like a car air-conditioning system.” Syed cites Carnegie Hall in NYC as an interesting historic example. “The cooling system was a grate in the sidewalk; an ice truck would dump slabs of ice into a vault,” he says. “Fans would blow the cool air under the seats cooling the house, and there was a fan off the top of the roof, which exhausted the hot air out into the open air.”
Another issue is focusing on where the load is, the people. “Each person creates a plume of heat around themselves due to body heat,” says Syed. “The contaminants generated by each person rise up and do not contaminate the rest of the area in a displacement system, where they don't go into the other person's plume. In a conventional system, you mix up all the air and make a big soup that's very hard to regulate, and here the contaminants mix and people breathe a soup of mixed air.
“Part of this plume that people exhaust contains a lot of moisture. You need to get rid of the moisture in the air to return it as cool air,” he continues. “To do this, you need to cool the air, and by cooling only the right amount, you can save energy. You can save 15 to 20% of energy by using a displacement system, where you have a 10° difference in the air you have to cool between 55° and 65°. The lifecycle of an AC unit is 20 years, which is a lot of energy-saving.”
The 20 years is just what an engineer looks at to determine energy savings. The AC unit, depending on maintenance, could last longer than that. A displacement system also helps with the acoustics of the theatre because the lower velocity makes less noise than the conventional system.
“In the Biltmore, when everyone started talking about re-raking the house, that gave us the ability to create a plenum in the theatre; this made it a perfect candidate for a displacement system,” recalls Syed. “This gives us an integrated design, and everybody has to work together, which ultimately is a more efficient use of space. On many projects, you end up doing your own work and not coordinating all of the elements, which is not very efficient in the end. But it takes a lot more work coordinating everything in the design phase.”
Displacement can be useful in theatrical and non-theatrical spaces. In New York City, the just-built New York Times building has a displacement system in the auditorium and offices. The Hearst Building in New York City will have a displacement system in the theatre and lobby. According to architect Chris Garvin from the firm Cook + Fox, “In the reconstructed Henry Miller Theatre in the Bank of America Tower at Bryant Park in NYC, all the HVAC is being supplied by a plenum from underneath, and, in fact, the entire building has a raised-floor system of legs and panels where you can pull out panels to change wiring or cover any future need for moving offices.”
This all leads to efficiency of space and energy, as well as having a green building, which will save you money and maybe even get you a financial reward, depending on your area. I recommend going to the LEED website, www.usgbc.com.
Todd Hensley, a theatre consultant at Schuler Shook, has many stories about deluge curtains or proscenium protection from fire. According to Hensley, “We see this a lot — deluge proscenium protection that goes off for the wrong reasons [component failure, mistaken testing procedure, etc.], creating a flood on stage and in any spaces below the stage. Who has one of these systems without a horror story?”
Hensley also notes that fire protection trunks and branches that run right through the active fly loft space need to be avoided. “‘What do you mean scenery goes up there? I don't see any scenery.’ You will often hear this from engineers,” he says. “Other problems are plumbing lines installed in the path of the rigging cables, causing the cables to act as slow-motion band saws. Or sprinkler heads installed right into active stage-lift zones, ready to be sheared off with the first use. Duct work that is installed as per the detailed drawings but sticks into the rigging should be moved by a few inches.” Hensley points to another problem — that of “HVAC systems on stage that produce too much air velocity blowing onto the scenery or on the stage. The mark of failure: big, clear baggies taped onto the supply grilles,” he says.
Chris Buckley of Production & Performance Facility Consulting LLC notes, “Deluges in a proscenium theatre are notorious for malfunction and causing massive amounts of water damage. You can point to many theatres that have a deluge system, and they have had an accident with it. They are there because they replaced asbestos curtains. Consider a Xetex fire curtain if at all possible.” Based on Buckley's advice, put your foot down early in the process about getting approval for a Xetex fire curtain. (Xetex is also used as a heat shield to protect lights that are near curtains.)
“In general, sprinkler locations need to be carefully coordinated in all production areas. Normally, stage sprinklers would have a layer of heads under the grid and one above the grid — on the ceiling — as well as under the galleries,” Buckley adds. “They should be located so they cannot be struck by moving equipment, and all heads should have protective cages.”
Sprinkler heads should have high heat vials. (These are the glass ampoules that boil, shatter, and then trigger the head.) With the engineer, you should discuss temperature settings, as they may be subject to heat from lighting fixtures. “A normal sprinkler head triggers at a fairly low temperature — 140°F — so it's a decision the engineer needs to be involved in,” advises Buckley.
It is also important to remember that HVAC ducts more than 5' wide are often required to have sprinkler coverage underneath them. In areas such as pits and trap rooms, sidewall heads may be possible, which eliminate the need for overhead pipes in low-ceilinged areas. In trap rooms, valves and removable sprinkler branches should be considered.
In short, make sure that the mechanical engineer is doing what everybody wants: keeping stuff clear of the scenery, orchestra pit covers, or lifts, and making sure you have a separate control on the stage from the house for heating and air conditioning. This should give you a very workable theatre that you will enjoy for many years.
As production director and director of capital projects for Manhattan Theatre Club, Michael Moody supervised the company's renovation of the Biltmore Theatre, completed in 2003.