Creating an efficient environment
The project design comprised a luxury pool that could be enjoyed year round in a pleasant, yet energy-efficient environment. A number of design methods and elements were used to achieve this goal, including:
An indoor pool requires the use of dehumidification equipment to maintain air quality. There is a constant battle between evaporating pool water and maintaining a tolerable level of humidity in the enclosed building. One solution is to turn off dehumidification equipment and open the enclosure, which allows the pool to be operated like an outdoor pool. In this case, the unique glass enclosure has automated, motorized roof panels that open and sliding doors in the vertical walls, which enable air to flow freely. On the hottest summer days, natural convection currents draw the hot air out of the enclosure and up through the roof. This particular pool enclosure is equipped with automated rain sensors, which close the roof panels during inclement weather. In the winter months, solar gain during the day is captured by the geothermal system and held for use during cold, dark nights.
In the spring and fall, the building is opened during the day and closed in the evening. This allows solar heat to be captured during daylight hours, while preventing the rapid nighttime cooling effect. There is a net gain in energy efficiency by the intelligent use of the flexible pool enclosure.
The overall esthetics of allowing in natural light, keeping out insects and providing an open air concept, while maintaining the ability to enjoy the pool any time of the year, are an added bonus for the client.
The most important item to add to a pool with regard to energy efficiency is an automated pool cover. Constructing an indoor pool without a cover will result in increased energy costs throughout the pool’s life. Various studies indicate upwards of 70 per cent of a swimming pool’s heat loss can be saved simply by installing an automated pool cover. In an indoor pool setting, this heat loss is further compounded, as evaporated water must be removed from the air by the heating, ventilating and air conditioning (HVAC) system. It is critical to keep the pool, chill pool and spa covered when not in use to maintain maximum efficiency and the ‘Thermos effect.’ For this project, the automated cover was installed in the underground bunker.
Ground temperature, a mere 1.2 m (3 ft) below the earth’s surface, is generally around 13 C (55 F) degrees. For this installation, the goal was to maintain the pool at 28 C (82 F), the chill pool at 14 C (58 F) and the hot spa at 39 C (102 F). To do this, rigid foam insulation was used beneath the building’s foundation, the full depth of the pool bunker’s interior walls, and the entire shell of the pool, chill pool and hot spa. It was also decided against using closed-cell spray foam on the bunker walls and pool shell for esthetic reasons, as it is unattractive compared to the clean, crisp lines of rigid foam insulation. (Note: Some building codes require insulation to be covered with drywall in an indoor environment when connected to a living space.) In this case, the insulation in the change and steam rooms, as well as the bathroom were covered with tile. Self-closing steel doors separate the mechanical room from the living space. As with all insulation, there is a diminishing return on investment (ROI). For example, twice the amount of insulation does not double energy efficiency results.
In addition to the foundation, shell and bunker walls, all of the plumbing lines were insulated, both inside and outside the concrete shell. All geothermal and water supply lines inside the building were also insulated. There was no compromise in energy efficiency by not insulating the project’s waste and drain lines.