The mechanical rooms are a work of art, with ultra violet disinfection units, pumps and high efficiency water filters.

The new 34,000 square foot North Cowichan Aquatic Centre building at Duncan, B.C. uses the latest technology to provide building heating, cooling and dehumidification. Water-to-water, water-to-air and air-to-water heat pumps provide building heating, cooling and humidity control for the 12,000 sq.ft. pool area. Heat loss from pool water evaporation is used for heating other areas of the building during the heating season and the heat pumps reverse to provide cooling during the summer.

Pool, occupied areas

The heart of system, designed by AME Consulting Group of Victoria, B.C., centers around four 30-ton water-to-water heat pumps providing eight stages of control.  Latent heat from pool water evaporation is recovered by cooling the return air using 45ºF (7ºC) water. Return air is cooled to below its dew point and water vapor (latent heat and sensible heat) is removed.

Heat pumps return the sensible heat, as well as compressor motor heat and heat of compression, by transferring it to the "hot side" reheat coil where it is returned to the pool area. Extra heat is circuited though a building hot side loop.  The  hot side loop temperature can get as high as 120ºF (49ºC). It is used by 11 water-to-air heat pumps to heat various occupied spaces throughout the building. When the building's heating load exceeds the recovered heat, a Trane 67-ton rooftop air-to-water heat pump provides additional building heat.

Two 25,000 CFM air handlers provide airflow through the pool area, with up to 20 percent outdoor air. 

Workout rooms

Workout rooms required a different approach to ventilation, heating and cooling. They require far more outdoor air and must be heated and cooled independently of the pool or other occupied spaces. Two Aaon  custom-built five-ton air-to-water heat pumps with an economizer section do the job. They use the hot side loop water to provide hot gas to heat incoming outdoor ventilation. The heat pumps are reversible and will cool outdoor air when required. The system is unique in as far as hot or cold refrigerant gas is used on the air side, eliminating problems often found with water coil freeze up.     

Hot side heat exchangers connected to the hot side loop are used preheat shower and DHW.  When recovered heat is not needed it is rejected through a closed circuit evaporative cooling tower. A gas -fired boiler provides backup heat if needed.

Building management system

Building management systems (BMS) are rapidly developing as all technologies are. Many management systems have been employed for as long as commercial buildings have existed. However, "BMS," as a phrase, is relatively new (past 20 years). The phrase has only really existed since the existence of complex electronic machines that are capable of retaining data written for the purposes of managing power, lighting, heating, etc. It is ideal for controlling heat pump systems.

A building management system is a computer-based control system that controls and monitors the building's mechanical and electrical equipment such ventilation, lighting, power systems, fire systems, and security systems. It consists of software and hardware; the software program can be proprietary using such protocols as C-bus, Profibus, etc. Recently, however, new vendors are producing BMS that integrate with internet protocols and open standards like DeviceNet, SOAP, XML, BACnet, Lon and Modbus.
A BMS is more typical in a large building. Its core function is to manage the environment temperature, and humidity within a building. As a core function in most BMS systems, it controls the production of heating, dehumification and cooling, manages the systems that distribute this air throughout the building, and then locally controls the mixture of heating and cooling to achieve the desired room temperature and humidity. Systems linked to a BMS typically represent 40 percent of a building's energy usage; if lighting is included this number approaches 70 percent. BMS systems are a critical component to managing energy demand.

Pool maintenance supervisor Randy Busch monitors the entire system from a central PC location, with an Atherton building management system supplied and installed by Cougar Pacific Systems of Victoria. The system consists of various pumps and three-way valves to control the flow and mix of treated water and deliver it to heat pumps throughout the building to provide heating, cooling and pool area dehumidification
The mechanical rooms are a work of art, with ultra violet disinfection units, pumps and high efficiency water filters. The heating and dehumidification systems were installed by Westbay Mechanical led by Dean Loewen and his crew. They did a fine job of installing the mechanical systems including piping the various heat pump water circuits, pumps, water treatment, and filtering.

Ed Gravelle is a consultant on refrigeration, air conditioning and heating systems based in Brentwood Bay, B.C. He can be reached at epgco.09@shaw.ca.

Pool maintenance supervisor Randy Busch can monitor the heat pumps from a central PC location.

The North Cowichan Aquatic Centre is a state-of-the-art pool facility designed with energy efficiency in mind.

Large pool projects require a lot of pumps and piping. This is the lower pump room.

Fig. 1: This chart illustrates the wide array of equipment installed in the facility.