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Energy Performance and Life Cycle Costing of Ventilation

University of British Columbia. Campus and Community Planning

Lot E and Site B are two projects under construction with two different ventilation systems. Due to the fact that space conditioning has dominated a great portion of energy consumption, our client - UBC Properties Trust, would like to determine the pros and cons of both ventilation systems for future reference. According to client’s request, we did some studies on both ventilation systems on regulation complexity, energy consumption performance, strategies used in the industry, architectural structure, and life cycle costing. For regulation complexity, 2012 British Columbia Building Code was reviewed. Both designs have met the criterion of the code. Comparing with mechanical ventilation system, natural ventilation system has more requirements. The most significant difference of requirements for natural ventilation system or combination of natural and mechanical ventilation were applied in occupant load during normal use, permits required for use of large openings in the building envelope even during the winter and restriction of occupancy of seasonal buildings. Thus, requirements and regulation for natural ventilation system is more complicated. For information of energy performance of residential buildings in Vancouver, a report about energy consumption in mid- and high-rise residential building in British Columbia published by RDH Building Engineering Ltd. was reviewed. In their study, consumption data from 39 samples were analyzed. As a result, the average energy consumption is 213kWh/m²/yr, and average energy consumption for space conditioning is 37%. Since ventilation system has the most effect on space heating energy consumption, simulation with data from 13 samples shows that with a constant make-up air flow rate, annual space heat consumption can goes up to 108.4 kWh/m²/yr in an environment with high leaky rate (windows open) and it can goes down to 96.7 kWh/mLot E and Site B are two projects under construction with two different ventilation systems. Due to the fact that space conditioning has dominated a great portion of energy consumption, our client - UBC Properties Trust, would like to determine the pros and cons of both ventilation systems for future reference. According to client’s request, we did some studies on both ventilation systems on regulation complexity, energy consumption performance, strategies used in the industry, architectural structure, and life cycle costing. For regulation complexity, 2012 British Columbia Building Code was reviewed. Both designs have met the criterion of the code. Comparing with mechanical ventilation system, natural ventilation system has more requirements. The most significant difference of requirements for natural ventilation system or combination of natural and mechanical ventilation were applied in occupant load during normal use, permits required for use of large openings in the building envelope even during the winter and restriction of occupancy of seasonal buildings. Thus, requirements and regulation for natural ventilation system is more complicated. For information of energy performance of residential buildings in Vancouver, a report about energy consumption in mid- and high-rise residential building in British Columbia published by RDH Building Engineering Ltd. was reviewed. In their study, consumption data from 39 samples were analyzed. As a result, the average energy consumption is 213kWh/m²/yr, and average energy consumption for space conditioning is 37%. Since ventilation system has the most effect on space heating energy consumption, simulation with data from 13 samples shows that with a constant make-up air flow rate, annual space heat consumption can goes up to 108.4 kWh/m²/yr in an environment with high leaky rate (windows open) and it can goes down to 96.7 kWh/mLot E and Site B are two projects under construction with two different ventilation systems. Due to the fact that space conditioning has dominated a great portion of energy consumption, our client - UBC Properties Trust, would like to determine the pros and cons of both ventilation systems for future reference. According to client’s request, we did some studies on both ventilation systems on regulation complexity, energy consumption performance, strategies used in the industry, architectural structure, and life cycle costing. For regulation complexity, 2012 British Columbia Building Code was reviewed. Both designs have met the criterion of the code. Comparing with mechanical ventilation system, natural ventilation system has more requirements. The most significant difference of requirements for natural ventilation system or combination of natural and mechanical ventilation were applied in occupant load during normal use, permits required for use of large openings in the building envelope even during the winter and restriction of occupancy of seasonal buildings. Thus, requirements and regulation for natural ventilation system is more complicated. For information of energy performance of residential buildings in Vancouver, a report about energy consumption in mid- and high-rise residential building in British Columbia published by RDH Building Engineering Ltd. was reviewed. In their study, consumption data from 39 samples were analyzed. As a result, the average energy consumption is 213kWh/m²/yr, and average energy consumption for space conditioning is 37%. Since ventilation system has the most effect on space heating energy consumption, simulation with data from 13 samples shows that with a constant make-up air flow rate, annual space heat consumption can goes up to 108.4 kWh/m²/yr in an environment with high leaky rate (windows open) and it can goes down to 96.7 kWh/m²/yr in an environment with tight rate. Knowing natural ventilation system tends to have a higher air leakage rate, it is believed that mechanical ventilation would perform better on saving annual space heat consumption. Previous studies gave us some strategies that may improve the energy efficiency and consumption for residential buildings. There are three most efficient ways which are improvingyr in an environment with tight rate. Knowing natural ventilation system tends to have a higher air leakage rate, it is believed that mechanical ventilation would perform better on saving annual space heat consumption. Previous studies gave us some strategies that may improve the energy efficiency and consumption for residential buildings. There are three most efficient ways which are improving/yr in an environment with tight rate. Knowing natural ventilation system tends to have a higher air leakage rate, it is believed that mechanical ventilation would perform better on saving annual space heat consumption. Previous studies gave us some strategies that may improve the energy efficiency and consumption for residential buildings. There are three most efficient ways which are improving glazing and wall assemblies, control airflow including make-up air ventilation strategies, and control air leakage. The study also provided some practical improvements. Varying makeup air temperature set-point between 13 to 23 degrees results in a significant difference in energy consumption. The architectural design for natural ventilation has more restricts in floor area, exposed wall area, window to wall ratio, overall wall and roof R-values, window U-value and window solar heat gain coefficient. Decreasing ventilation air flow rates up to 60% of the nominal flow rate would be optimal. Finally, it is very practical to provide heating and ventilation directly to each suite. Using the in-suite approach is more economical considering the cost for ductwork and fire-dampers. The mechanical drawings were reviewed, compared, and checked for conformance to best practices. Lot E had significantly less ducting requirements, which saved material and space use. Also, each apartment was isolated from the main ventilation system, reducing fire risk and stabilizing energy requirements. It had at least three times as many exterior penetrations as Site B, which will likely increase air leakage. Lot E also had more pieces of equipment, which will likely require more maintenance time. One possible improvement for Site B would be to incorporate the dryer exhaust into the HRV, which, while intermittent, presents a significant heat recovery potential. Reports of energy modeling for both projects were reviewed. For Site B, EUI of the building design is 136.6 kWh/m²/year and it meets the energy efficiency target for REAP gold plus certification. The result of Lot E modeling shows that EUI of Lot E (base design) is 176.5 kWh/m²/year which is higher than REAP gold certification EUI target 163.8 kWh/m²/year. Cost calculations with respect to lifetime of ventilation systems (20 years) for the two projects were carried out. Using Net Present Value (NPV) calculations at nominal discount rate of 5% and inflation of 2% the real discount rate was calculated to be 3%. The maintenance cost and yearly energy cost (District Energy System rates) were accounted for. The NPV values were normalized by dividing the results by residential area. This made the results directly comparable (NPV/m²). The residential area was used, rather than total building because the residential ventilation systems are being compared. The results favor the ventilation system Lot E. Disclaimer: “UBC SEEDS provides students with the opportunity to share the findings of their studies, as well as their opinions, conclusions and recommendations with the UBC community. The reader should bear in mind that this is a student project/report and is not an official document of UBC. Furthermore readers should bear in mind that these reports may not reflect the current status of activities at UBC. We urge you to contact the research persons mentioned in a report or the SEEDS Coordinator about the current status of the subject matter of a project/report.”

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UBC Social Ecological Economic Development Studies (SEEDS) Student Report; University of British Columbia. APSC 598G

Vancouver : University of British Columbia Library

10.14288/1.0343221

Applied Science, Faculty of

Graduate

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