Acoustics, Daylighting and IAQ
- By Larry Wente
- February 1st, 2010
School administrators are under immense pressure to provide the best of everything — the highest test scores, the best learning environment and the most energy- and cost-efficient facilities. And with budgets being squeezed more than ever, building a new school facility — the best facility, of course — can seem an impossible task right now.
As architects, we’ve worked with school administrators who face the daunting challenge of designing and building a much-needed facility when budgets are tight. The good news is that in our experience, a school can build a high-quality facility on even the tightest budget. The key is to balance the budget against end-user needs by setting clear priorities, making tough decisions early in the design phase and implementing some creative measures.
When designing a great facility on a tight budget, there are three key areas of indoor environmental quality on which to focus: acoustics, daylighting and indoor air quality (IAQ). With the right design efforts, all three elements can improve student performance, occupant health and comfort, and cost and energy efficiency.
When building a new facility, good acoustics start with site selection. Ideally, the location will be situated away from external noise sources such as highways, airports or railroad tracks.
Often, an acoustically perfect site is not an option. If your budget dictates that a site near traffic or other noise sources is most practical, then decisions must be made during the design phase to minimize detrimental effects.
We recently wrapped up such a project in Teaneck, N.J. Having shared a cramped space with an all-girls high school since 1998, the Teaneck Community Charter School was ready for its own facility. Operating on a very modest budget, we worked with school administrators to make some hard choices, starting with site selection.
The chosen location was a perfect site for the new school, in many ways. It was in a quiet neighborhood, offered sufficient space and was within the school’s budget. But it also sat adjacent to regularly used railroad tracks.
When an acoustic challenge such as this presents itself, window glazing systems and sound-attenuation insulation can be an effective and cost-efficient solution. Windows provide varying degrees of sound and thermal insulation. Laminated glass, which has a protective vinyl interlayer, is a good choice for safety purposes, and also serves to dampen some sound.
A more difficult issue is choosing the number of glass sheets used to assemble the windows. Double-glazed windows will cost less, and depending upon the proximity of the external noise source, they may offer sufficient protection from sound. But if the planned facility sits directly adjacent to a noise source such as a high-traffic road, triple-glazed windows will likely be a wise investment. Although more expensive, the sound insulation will be far more effective — and the greater thermal insulation can translate to saved energy costs.
Conscious of the school’s budget in designing the Teaneck school, we knew that using triple-glazed windows throughout the facility wasn’t an option. Instead, we planned for laminated triple-glazed windows along the side facing the railroad tracks, thereby effectively minimizing the exterior sound intrusion while keeping costs reasonable.
A drab and rundown former warehouse from the 1940s, the Teaneck building itself presented unique design opportunities. Adaptive reuse projects such as this can be a cost-effective choice, and former industrial buildings generally have many of the qualities sought in a school facility, such as high ceilings, fireproofing and a generous base with fewer columns, which allows for more flexible layouts. When design begins, it is little more than a shell; but it can provide an ideal framework for the systems and infrastructure that a school requires.
The Teaneck building’s concrete warehouse construction, with no insulation, allowed for some cost-saving creativity. We installed sound-attenuation insulation on the outside of the concrete and then clad it with bright red metal, producing an important element of the insulation system that doubled as a striking design feature. You can create a powerful and cost-efficient impact just through the use of color. For example, Teaneck’s rooms are color-coded by grade, which minimized the need for signage.
In addition to exterior disruptions, interior noise will inevitably spring from sources that include children and teachers in neighboring classrooms, HVAC and plumbing systems and hallway activity. Thoughtful design in systems placement and interior materials can minimize distracting noises in classrooms.
Sound attenuation insulation between rooms is an effective way of preventing classes from disturbing each other, but the placement of HVAC and plumbing systems is a key design decision that, if poorly planned, can result in maddening rattles, groans and reverberations. It is vital to isolate plumbing in hallways in order to prevent classroom interruptions. Reverberations from hard surfaces should be dampened with overhead panels. At Teaneck, we paid particular attention to this in two-story areas such as the library, cafeteria, kindergarten area, common area and some hallways. The result was a quiet facility whose environment promotes studying and learning.
For decades, the prevailing belief among school designers was that windows distracted students and increased heating and air conditioning costs. The result was tiny windows.
But since the late 1990s, studies have repeatedly shown that ample windows and natural daylight correlate directly to increased student performance, while also influencing occupants’ comfort and health. Advances in window glass have reduced the problem of insulation. And as sustainable design and LEED certification become increasingly important, effective daylighting is an important tool for reducing a school’s dependence on artificial light, boosting energy efficiency and cutting costs.
An often-overlooked element of daylighting is, simply, proper planning. Poorly designed daylighting can result in glare, shadows and bright spots. Daylighting can be an extremely effective and cost-efficient way to improve energy savings and occupant well-being, but it is crucial that the project architect accurately model the effects during the design phase to avoid costly mistakes later.
In its previous location, Teaneck’s space had been confined to the interior of the building — there was not a single window, forcing the school to rely entirely on artificial lighting. We challenged ourselves to bring natural light to every corner of the new facility. Keeping the budget in mind, we decided that larger window area was crucial, and we gave classrooms the greatest possible amount of window space while planning carefully to avoid any negative effects from the daylighting. In interior spaces, where windows were not an option, we used skylights and atriums to bring in “borrowed” light, fulfilling our goal of supplying natural light to every room.
In addition to using the windows’ location and size, a design can incorporate sunscreens and external fins to control daylighting. When installed at the proper angle, sunscreens and fins block heat gain from the high summer sun while allowing light from the lower winter sun to enter the room.
But even in a daylight-flooded facility, energy and money can be wasted if lights are not switched off or are brighter than necessary. Light sensors are an affordable and easy way to ensure that artificial light is only used as necessary. When there is sufficient natural light coming in, the sensors will automatically dim the lights to the appropriate level.
Indoor Air Quality
On a tight budget, IAQ is a factor for which tough decisions absolutely must be made early in the design phase if budget is to be balanced with needs. The type of HVAC system (Heating/Ventilation/Air Conditioning) chosen will have a major impact on both budget and indoor environmental quality.
The most important decision regarding HVAC systems is whether to use a Continuous Air Volume (CAV) or a Variable Air Volume (VAV) system. A CAV system is cheaper, but offers only one temperature setting for multiple rooms. Essentially, you trade cost for controllability. A VAV system, on the other hand, can allow separate thermostats for multiple rooms. So while it is more expensive in upfront costs (by as much as 20 percent), a VAV system offers greater control in each room. This leads to increased efficiency in heating, cooling and maintaining humidity levels in the facility, which translates to greater cost efficiency.
Another tool to improve IAQ is the inclusion of operable windows. After decades of fixed windows as a standard feature in school design, there is finally a movement to have greater operability. Operable windows allow for natural ventilation and can go hand-in-hand with daylighting to improve student performance and reduce stress. For those reasons, Teaneck Community Charter School now has operable windows in every classroom.
The Teaneck project demonstrates that it is, in fact, possible to design a school facility with terrific indoor environmental quality, even on a tight budget. It simply calls for advance planning and early decisions that promote good acoustics, daylighting and indoor air quality. Students do best when they do their studying ahead of time; when it comes to design, smart schools should do the same.
Larry Wente is a co-founder of Gertler & Wente Architects in New York City. He can be reached at firstname.lastname@example.org or at 212/273-9888.