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AUGUST 2017 | 43 Mechanical & HVAC Systems PHOTOGRAPHY COURTESY THERMENEX A focus on Passive House is changing the world of mechanical and HVAC systems by NATALIE BRUCKNER-MENCHELLI I t has been well documented that mechanical systems providing indoor environ- mental control and domestic hot water functions generally represent the larg- est consumer of energy in Canadian high-rise multi-unit residential buildings. However, as government, owners and end users shine a spotlight on the sec- tor, leaders in the field have taken it upon themselves to drive mechanical and HVAC systems towards a more sustainable future and are participating in R&D efforts to ensure buildings are optimized and can actually achieve the energy goals of not just today, but 30 years from now. "New buildings are becoming more and more energy efficient based on munici- pal policies and regulations, however this only accounts for a minor percentage reduction of the overall energy consumption. Existing buildings designed and con- structed are not subjected to the same rigid energy requirements," says Vancouver- based engineer Gideon Loh from Norman Disney & Young (NDY). However, Loh adds that between the lack of incentives to upgrade existing buildings to improve energy performance and municipal policies, and regulations to meet energy standards, reduction of energy consumption is not a high priority of building owners. Over the past 12 months Loh says modifications to the local/municipal code to meet benchmark energy targets and ultimately achieve significant reductions in carbon emissions has resulted in a greater focus on the integration of individual mechanical systems (such as space cooling/heating, domestic hot water and sew- age waste) to share "waste" heat. Examples of this include the extraction of the heat generated from electrical motors, transformers, elevator machine rooms and electrical rooms to preheat domestic hot water. For one project, the heat extracted from the sewage waste gen- erates 85 percent of the domestic hot water requirements, thus reducing natural gas consumption and carbon emissions. In addition, there is increasing focus on the utilization of excess heat from cooling plants to preheat domestic hot water prior to discharge to a cooling tower, as well as the use of ocean sea water to extract or reject heat based on building requirements. Measuring and managing energy consumption is key, says Loh: "The design and installation of the most advanced system does not equal an efficient building. Metering is a means to determine the actual performance of the building based on the occupant demand," he explains. "The biggest influence I see on the mechanical/ HVAC sector will be the modification to the operation of the systems to meet the occu- pant demand based on peak and non-peak requirements during different seasons." Over at Williams Engineering Canada Inc., the highly skilled team of mechani- cal engineering specialists are constantly optimizing key strategies in an effort to maximize efficiencies and minimize wasted energy, and are investing in new tech- nologies and education to take the sector towards a lean and sustainable future. "The City of Vancouver's Zero Emissions Building Plan has a new green build- ing policy to achieve zero emissions for new buildings by 2030. This is driving the building industry to revisit conventional ways and be creative to meet those goals," explains James Y. P. Lee, regional director at Williams Engineering. Turn Up The Heat One way to achieve this is through heat recovery ventilators (HRVs) that use a heat recovery ventilator, heat exchanger, air exchanger, or air-to-air heat exchanger that employs a cross flow or counter-flow heat exchanger between the inbound and outbound air flow. "The City of Vancouver is at the forefront of this movement," explains Peter Kuo, mechanical team lead at Williams. "HRVs offer improved efficiency and superior ventilation, and are the shortest path to meeting new Code requirements. But they have to be installed properly." Williams is currently working on a groundbreaking new project in Vancouver due to be completed by 2022. The project will feature a 45- and 50-storey build- ing and consist of HRVs, as well as a number of other new technologies to meet many stringent targets set by the City (such as Green Building Policy for Rezoning, General Policy for Higher Buildings and City of Vancouver Neighbourhood Energy Interpretation Guide for Rezonings). "The building will demonstrate leadership in sustainability, and we are using mechanical systems to help achieve those targets," says Lee. "In addition, the under- ground parkade has a ventilation tunnel using a concrete wall on one side with a cavity behind that has a metre space in between. The air drawn from the outside into the tunnel will be preheated and pre-cooled prior to entering into the building ventilation system. This mimics a geoexchange system as we use the ground tem- perature, and is quite a unique and simple way to take advantage of relatively con- sistent ground temperature throughout the year." Kuo adds that Vancouver's plan for all new city-owned and Vancouver Affordable Housing Agency projects to be built to certified Passive House standards is also hav- ing an impact on the sector. Heat recovery from the waste water, such as the bath- room and kitchen sewer heat recovery, is becoming more common. Passive House buildings must have an annual heating and cooling demand of not more than 15 kilo- watt hours per square metre of building (15 kWh/m²) per year, and total primary energy (calculated as source energy, not metered energy at the building) must not exceed 120 kWh/m² per year. Passive House buildings typically require a mechani- cal ventilation system with HRV to run 24 hours a day. This leap to Passive House standards means that conventional heating systems design needs to evolve, and buildings can be heated with considerably minimal amounts of heat input with the ventilation air distribution system or other low energy input systems. Kuo adds that technologies are evolving every year and he expects to see other alternative energy sources such as solar energy having a greater influence on mechanical and HVAC systems in the near future. B.C.-based Thermenex, which uses patented technology to fabricate thermal energy plants for HVAC systems in large buildings, has always taken a holistic approach to building reclaim. "As an industry we need to understand that every heating system is a cooling system and vice versa. When you cool a building, you are heating the outside. The traditional design approach focuses on one side of thermal exchange, but we believe the future is optimizing both sides of energy exchange for every system," says Jeff Weston from Thermenex. "Every HVAC engineer can design a boiler system to heat a building, but how many think about designing a building to cool a boiler?" The Thermenex system has been shown to reduce greenhouse gas emissions (GHG) by as much as 93 percent, and energy cost savings up to 59 percent. Thermenex-In-A-Box system at the NexSource Centre, Sylvan Lake, AB. 2:55 PM

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