Issue link: http://digital.canadawide.com/i/354800
E Blowing Hot & Cold THE HVAC SECTOR IS DEVISING AND DEPLOYING A RANGE OF QUASI- RENEWABLE SYSTEMS by Godfrey Budd The grid-based design allows for an expanding network to optimize heating and cooling sources and reclaimed water for the planned 210-hectare community. Another HVAC system that is geared to cut energy costs sharply is from Thermenex. The company uses well-known refrigeration principles and a patent pending technology to create a thermal gradient within a pipe, which has hot water at one end and cold at the other. "Large buildings are a thermal resource. Unlike ground source, which extracts heat from the ground by cooling the ground, we optimize the inherent build- ing thermal energy to heat the building. We take heat from the building spaces themselves – the exhaust or the sanitary waste. The header pipe directs water that has the minimum required thermal content to satisfy the load at the required location in the building. We do not make water any hotter or colder than the demand. No external resources are used for heating until the building has re-used all of its own energy. The pipe typically loops around the mechanical room and functions as an energy hub," says Ian Hall, a principal at TC Thermenex Inc. Nearly a dozen Thermenex systems have been deployed or are under construction, including buildings at the Univer- sity of British Columbia and a sports and leisure centre in Coquitlam. "The system works well for large buildings and complexes with varying load profiles. We are doing a curling and aquatic complex in Cochrane." says Hall. He notes that the system is also being applied as a District Energy Solution. Distances between buildings in a munici- Energy efficiency continues to be a prior- ity and a driver of innovation in the Cana- dian HVAC sector, but the promise of at least one type of system – ground-source- based geothermal – may have fallen some- what short. Other technologies, however, have been succeeding at cost-effective systems with a renewable component. With this geothermal approach, often called geo-exchange, the ground beneath and/or adjacent to a building is used as a heat sink in summer and a heat source in winter. Hot rocks, thousands of feet below the surface, are typically not part of the picture in this scenario. In the 2004 to 2005 period, when natural gas prices tripled, interest in geothermal alternatives spiked. "Geo- exchange technologies sprung up all over B.C. and other provinces. It was a natural evolution as owners and operators were faced with rising and unbudgeted utility costs," says Steve Woodmass, regional director for B.C. with Williams Engineering Canada. But the bloom was soon off the geo- thermal rose. Gas prices had cratered after 2009 and have stayed low since then, cutting the potential utility bill savings of the alternative heat and cool- ing source. Also, costs for electricity, essential for geo-exchange pumps, have drifted steadily upwards. "The reality is that geothermal-based HVAC solu- tions are only financially advantageous when utility cost structures align, like they did in 2004. Back then, a coefficient of performance for a heat pump could generate a 10-year or simple payback or even less," Woodmass says. With today's current prices, though, payback times might be better counted in decades. "Ground source geo- exchange payback can be 30, even up to 50 years," says George Steeves, presi- dent of Sterling Cooper Consultants Inc. As Woodmass points out, however, higher natural gas prices could return if and when B.C.'s proposed liquid nat- ural gas export industry to Asia ever gets off the ground. "In addition, full dependence upon electricity or natural gas is most likely not a great concept because time has shown that utility rates change, and so the operation of the building must adjust, assuming operat- ing costs matter," he says. Ground source geo-exchange may be less favoured for now, but other thermal exchange technologies are seeing the light of day, as some owners and HVAC specialists are taking steps to address Woodmass's point about utility costs. A District Energy Sharing System (DESS) is one such technology. It was developed by principals at Titus Infra- structure Services Limited, a company that partners with developers to utilize multiple local potential energy sources to set up integrated energy and water sharing systems. "I got involved when an owner wanted to make a renewable project profitable in the areas of energy and water," says Erik Lindquist, a principal at Titus Infrastructure Services Limited. He makes the point that a conventional district system supplies hot water at 65 to 80 degrees Celsius because of domestic hot water requirements. "But that's only 10 per cent of demand. So they supply 100 per cent of their product to address 10 per cent of demand. With a Titus sharing sys- tem, we provide a warm pipe at 15 to 30 degrees Celsius and a cool pipe around 10 degrees, so a building takes heat from the warm pipe and rejects the cool water," says Lindquist. DESS uses energy sources available within a community, including geo-exchange (if conditions are favourable), lake water, wastewater treatment, ice rinks and buildings. At its Westhills project in Whistler, there are approximately 350 single family homes connected to the DESS, but the number is growing, according to the Titus website. The project has reduced community energy supply requirements by "over 40 per cent" and is anticipated to exceed 50 per cent energy sup- ply reduction as commercial areas are developed. A geo-exchange borefield beneath a soccer pitch currently meets almost all the new subdivision's energy requirements between April and October. Heat pumps provide homes with heating and cooling – only 50 per cent of peak capacity, but 95 per cent of annual heating and 100 per cent of cooling. The remaining energy requirement is provided by conventional heat. Also, the system and homes are designed to utilize and distribute reclaimed water when a source becomes available. Curling ice at the Poirier Sport & Leisure Complex, Coquitlam, B.C. Photo courtesy IMEC Mechanical Ltd. AUGUST 2014 /47 Mechanical and HVAC Systems