Permeable paving systems can absorb rainwater, rather than increasing runoff, demonstrating the value of designing with nature. Collecting rainwater from the roof in a clear acrylic tank which can then be piped to exterior hose bibs for watering the lawn or flushing toilets can demonstrate how much water is wasted in non-green facilities and is used for such everyday functions as hand washing. Treating a natural, or man-made, drainage swale as a wetland and planting native wetland plants can demonstrate how water is cleansed and returned to the environment after a rainstorm and can also attract animals and birds to the more natural environment.
Contrary to popular belief, well-designed, sustainable schools can be built for approximately the same construction budget as an ordinary, non-sustainable school; the benefits include long-term savings in operation and maintenance costs as well as minimizing the impact of the construction on the environment.
Energy Conservation: Science lab facilities use significantly more energy than standard classrooms for several reasons: (1) fume hoods use the most energy, (2) higher outdoor air requirements for safe occupancy require more energy to condition the air (heat, cool, dehumidify, etc.), and (3) electrical plug loads in science facilities are 4-5 times higher than in standard classrooms. Thus it makes financial as well as environmental sense to design school science facilities to be as energy-efficient as possible.
During tours of many schools around the country, we have noticed that fume hoods are often kept running all the time – usually because the general ventilation system of the science area is inadequate. Often these fume hoods are also used as storage spaces and the sash of the hood is left open. Since the exhaust fans for fume hoods are designed to create a certain “face velocity” of air flow across the hood opening, the larger the opening, the more energy is expended by the fan to create this face velocity. Further, since air from the fume hood is exhausted directly outdoors, new outdoor air must be introduced into the school to replace it. This air must be heated or cooled, humidified or dehumidified to obtain the appropriate comfort level in the classroom. Both these activities waste energy. The solution is to design the science area’s HVAC system to provide adequate ventilation when the fume hoods are not operating, to design the supply fans in that system so that they provide additional outdoor air when the hood is turned on (a variable volume or “VAV” system), and to operate the hoods only when needed for classroom demonstrations or investigations.
Because science facilities use chemicals that create unpleasant and, sometimes, unsafe emissions, the ventilation system serving the science areas should be separate from the system serving the rest of the school. Science facilities generally require between 4 and 12 air changes per hour (ASHRAE Laboratory Design Guide, p. 32); a good general level for high school science lab/classrooms would be six air changes per hour (ACH) which means that all the air in a space is replaced by fresh air every ten minutes. All this fresh air must be conditioned (heated, cooled, humidified or de-humidified) which takes energy. Concentrating science facilities in a central area can minimize the need for duplicate, energy consuming HVAC equipment and can allow straighter and shorter air supply duct runs (which increases air flow and uses less energy). Further, with fewer machines required to heat, cool and move the air, there are fewer machines to maintain, which should reduce maintenance costs.