CCP 01-13-2003 - Laserfiche WebLink

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, . . . Pinewood Elementary School Final Commissioning Report Systems Overview 20 August 2002 Displacement Ventilation, a relatively new concept in this area, was chosen by the Mounds View School District as its primary school ventilation system. The design accepted by the District provides quality indoor air at a controlled temperature and dewpoint. The Commissioning Team has found when systems are operating within design perimeters they met the design intent of the School District. Prior to the remodeling, each classroom had its own unit-ventilator, which provided a certain amount of conditioned air to the space. This was adequate for heating but lacked the ability to cool the space and provide the required outside air for ventilation. The new design not only allows for cooling but also delivers the required amount of outside air to each classroom. Now each classroom has its own small air-handling unit called a Fan Powered Variable Air Volume Box. This is similar to a home heating system. It takes air back from the space and re-circulates it through the fan back into the space. However, this is where the similarity ends. Each of the new FPV A V Boxes also has the ability to receive a pre-designed amount of outside air. This is delivered by two new rooftop air handling units. This outside air is then mixed with the re-circulated room air and sent back into the space. A slightly less amount of air is exhausted from the building. Nearly 20,000 cubic feet of outside air is entering the building every minute just from the two new air handling units. Under the current guidelines of 15 CFM per person, this would be enough to meet the requirements of over 1300 students and staff. This constant flow of outside air meets current State guidelines. In addition, a desiccant drying system is reducing the moisture in the outside air to levels required to maintain a low dewpoint in the building. This allows for higher space temperatures while still maintaining comfort levels. As with any new system, problems have occurred. During commissioning, control sequences for the desiccant system were discovered to be wrong for this application. This has resulted in higher then designed building dewpoints. The sequences are being revised and will be operational before school begins. Large unconditioned spaces, such as gyms and cafeteria, have adversely affected the conditioned spaces, occasionally causing coils to sweat in the FPV A V boxes. School officials have instructed all personnel to keep gym and cafeteria doors closed at all times to alleviate this condition. Outside temperatures and humidity have exceeded the design limits for the installed equipment on numerous occasions last year and this year. This has resulted in coils sweating and high space temperatures. These conditions are being addressed by the design team and measures will be taken to prevent past problems from returning. 4