Energy savings
The engineer’s specification of a dual-compressor dehumidifier and an automatic pool cover will save the homeowner thousands of dollars annually in energy costs, as both strategies take into account the homeowner uses the pool area a small percentage of the day.
The dual compressor strategy operates one 8-ton compressor to maintain RH during idle times and the majority of family swim periods. The second compressor is automatically activated by the dehumidifier’s command centre if the temperature of the space or RH levels are not satisfied (e.g. during extremely cold days, start-ups after retractable window closing, or the party mode). The automatic pool cover significantly reduces water evaporation, thus the compressor has significantly less run-times during idle periods.
Air distribution design is critical
The engineers’ air distribution design is equally as important as the dehumidifier for keeping windows clear of condensation. A 711-mm (28-in.) diameter spiral metal rooftop drop and metal tee supply two 609-mm (24-in.) white fabric duct lines. The duct, mounted 3 m (10 ft) high, nearly encircles the perimeter and is supported by custom-fabricated white architectural wall-hanging brackets. The engineer ordered a linear air diffusion pattern angled to keep the windows above and below bathed evenly in warm, dehumidified air that is above the outdoor dew point.
A sustainable building envelope
The homeowner felt the best complement to the grandeur of the early 1900s marble-and-brick three-storey home would be a modern concrete and steel roof pool enclosure. The design evolved into an eclectic, contemporary addition using sustainable building materials. For example, the heavily insulated foundation/deck and steel roof deck have an R-value of 35 and 52, respectively. The windows carry a solar heat gain coefficient (SHGC) of 0.24, a U-factor (rate of heat loss) of 0.17, and a visible transmittance (VT) of 0.21.
An interesting design aspect is the windows above the ductwork are vertically aligned with the windows below the ductwork, even though they do not open and subsequently their custom millwork frames are smaller.
The pool support equipment is also state-of-the-art and anchored by a diatomaceous earth (DE) filter and back-up pool heater, which only activates during extremely cold days when the dehumidifier cannot maintain free pool water heating through compressor waste heat recovery, or when the dehumidifier is operating in a fan-only mode during outdoor pool modes. The pool is also equipped with an ultraviolet (UV) water sanitation system.
Keeping connected for sustainability
The homeowner uses the dehumidifier’s proprietary web browser-based monitor and control interface to help keep the HVAC system operating efficiently. Older dehumidifiers can run inefficiently for months between annual service check-ups; however, the homeowner’s smartphone app allows him to log-in on real-time and view historical data reported from the command centre for more than 60 operating parameters or receive an alarm within seconds of an operational inefficiency.
This is also an important reason to run the dehumidifier’s fan only in its lowest speed during outdoor operation so all the sensors are continually transmitting data to the web browser-based software in the event the homeowner wants to review any humidity or temperature readouts.
Thanks to modern technology, intuitive engineering, and a well-built building envelope, the homeowner will reap hundreds of thousands of dollars in energy savings during the indoor pool lifecycle, while also experiencing the ultimate of indoor air comfort. Further, it also functions successfully as an outdoor pool due to querying the homeowner on the pool’s foreseeable uses, which is critical in its design.
Ralph Kittler, P.Eng., is vice-president of sales at Dehumidified Air Solutions (DAS) based in Montreal, Que. He is the co-founder and former vice-president of sales/marketing at Seresco Technologies, an Ottawa-based mechanical dehumidifier manufacturer brand of DAS. Kittler is an American Society of Heating, Refrigerating, and Air-Conditioning Engineer (ASHRAE), distinguished lecturer, and the reviser responsible for Chapter 25 (‘Mechanical Dehumidifiers and Related Equipment’) for the 2012 ASHRAE Handbook: HVAC Systems and Equipment. Kittler can be reached via e-mail at ralphkittler@dehumidifiedairsolutions.com.
