Drake Landing Solar Community

The Drake Landing Solar Community (DLSC) is a planned community in Okotoks, Alberta, Canada, equipped with a central solar heating system and other energy efficient technology. This heating system is the first of its kind in North America, although much larger systems have been built in northern Europe. The 52 homes (few variation of size and style, with average above-grade floor area of 145m2) in the community are heated with a solar district heating system that is charged with heat originating from solar collectors on the garage roofs and is enabled for year-round heating by underground seasonal thermal energy storage (STES). The Drake Landing Solar Community (DLSC) is a planned community in Okotoks, Alberta, Canada, equipped with a central solar heating system and other energy efficient technology. This heating system is the first of its kind in North America, although much larger systems have been built in northern Europe. The 52 homes (few variation of size and style, with average above-grade floor area of 145m2) in the community are heated with a solar district heating system that is charged with heat originating from solar collectors on the garage roofs and is enabled for year-round heating by underground seasonal thermal energy storage (STES). The system was designed to model a way of addressing global warming and the burning of fossil fuels. The solar energy is captured by 800 solar thermal collectors located on the roofs of all 52 houses' garages. It is billed as the first solar powered subdivision in North America, although its electricity and transportation needs are provided by conventional sources. In 2012 the installation achieved a world record solar fraction of 97%; that is, providing that amount of the community's heating requirements with solar energy over a one-year time span. In 2015-2016 season the installation achieved a solar fraction of 100%.. This was achieved by the borehole thermal storage system (BTES) finally reaching high temperature after years of charging, as well as improving control methods, operating pumps at lower speed most of the time, reducing extra energy need as well using weather forecasts to optimize transfer of heat between different storage tanks and loops. During some other years, auxiliary gas heaters are used for a small fraction of the year to provide heat to a district loop. System do operate at coefficient of performance of 30. There are 52 homes in this subdivision that contain an array of 800 solar thermal collectors (2293m2 total gross area). These solar collectors are arranged on the roofs of garages located behind the homes. During a typical summer day these collectors can generate 1.5 mega-watts of thermal power. A glycol solution (an anti-freeze solution; a mixture of water and non-toxic glycol) is heated by the sun’s energy and travels through insulated piping underground through a trench system to the heat exchanger within the community’s Energy Centre. This is known as the Solar Collector Loop. The glycol solution then transfers its heat to water located in the short-term storage tanks. The District Heating Loop begins with water being heated in the heat exchanger to a temperature of 40-50 °C within the Energy Centre. This lower temperature is more energy efficient, as solar collecting is more compatible with lower temperatures. This increases the total amount of heat available to each home. In the warmer months the previously heated water is taken from the short-term storage tank to the Borehole Thermal Energy Storage (BTES). The Borehole Thermal Energy Storage unit is 144 holes located 37 m (121 ft) below the ground and stretches over an approximate area of 35 m (115 ft) in diameter. The water returns to the short-term storage tanks in the Energy Centre to be heated again in order to complete the circuit. During colder months the water from the BTES passes back to the short-term storage tank and is then directed to each home. Similar to a hot water tank, the heated water goes through a heat exchanger that blows air across the warm fan coil. Heat travels from the water to the air and is directed through the house via ductwork. When the temperature reaches that said on the thermostat, an automatic valve shuts off the heat transfer unit. The Energy Centre building is a 232 square metre (2,500 square feet) building which began operation in 2007.. It is located in very close proximity to the all 52 homes that are using it. It is home to the short-term storage tanks and most mechanical equipment such as pumps, heat exchangers, and controls. The Solar Collector Loop, the District Heating Loop, and the Borehole Thermal Energy Storage Loop pass through the Energy Centre. Two horizontal water tanks occupy the majority of the space within the Energy Centre. These tanks are 12 ft (3.7 m) in diameter and 36 ft (11 m) in length. The remaining space within the Energy Centre houses pumps, valves, heat exchangers and other necessary equipment to operate and control the energy system. These tanks are known as Short-Term Thermal Storage (STTS).