Mechanical matters
The pool house’s HVAC unit was a stand-alone system, disconnected from the main house. Supply registers were placed above the windows to keep warm air flowing over the surface, preventing condensation. Because of the airtightness of the structure, controlled mechanical ventilation (at rates defined by American Society of Heating, Refrigerating and Air Conditioning Engineers [ASHRAE] Standards) was provided via a heat-recovery ventilator (HRV). Lastly, the design team set out to control humidity by installing a separate dehumidification system decoupled from the heating and cooling systems. The target relative humidity range was 50 to 60 per cent.
Occupant behaviour
In addition to the careful design and construction of the project, the builder also coached the homeowner on how to keep relative humidity down and lower the run time and energy usage of the dehumidification system. First, to minimize evaporation, the clients were counseled to use the pool cover whenever the pool is not in use. They were also advised to set the pool water temperature one to two degrees ( lower than the pool house air temperature and keep it lower than 26.6 C (80 F) to slow the evaporation rate.
Conclusion
By managing the moisture hazard on multiple levels, MZO Group designed an enclosure that will ensure the client’s indoor pool will last a long time. By providing an effective air barrier, along with a moisture vapour retarder to the warm side of the insulation, the probability that moisture will enter the wall assembly (where it could condense and cause mould or rot) is minimized. The proper amount of insulation and high-quality windows ensure condensation does not occur on the interior surfaces.
By designing the indoor space as though it were outdoors, bringing in the mechanical contractor early in the design process and ensuring high-quality, detail-oriented work by subtrades, the project team was able to design and build an outstanding structure that will withstand the challenges of a difficult environment.
Jason Smith is the market development specialist in the Americas region for the Spray Polyurethane Foam (SPF) team within the Polyurethanes Division of Huntsman. Jason has eight years of experience in the chemical industry, including both technical and commercial roles. He can be reached via e-mail at jason_smith@huntsman.com.
