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Retrofitting a high-rise residential building to reduce energy use by a factor of 10



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This thesis details the ways in which energy is consumed in an existing Canadian high-rise apartment building and outlines a strategy to reduce its consumption of grid purchased energy by 90%. Grid purchased energy is targeted because the building is located in Saskatchewan where energy is predominantly generated from fossil fuels that release greenhouse gas emissions into the environment. Greenhouse gas emissions are targeted because of the growing consensus that human activities are the cause of recent global climate destabilization and the general trend towards global warming. Energy consumption is also a concern because of anticipated resource shortages resulting from increases in both global population and average per capita consumption. Many researchers are beginning to claim that a factor 10 reduction in energy use by industrialized nations will be required in order for our civilization to be sustainable.The building that was studied is an 11 story seniors high-rise with a total above ground floor area of 8,351 m2. It was constructed in 1985, in Saskatoon, SK, and it is an average user of energy for this region of the world and for a building of its size and type. Numerous field measurements were taken in the building, both during this study and previously by the Saskatchewan Research Council. These measurements were used to create a computer model of the building using EE4. After the computer model of the building was created different energy saving retrofits were simulated and compared. Over 40 retrofits are presented and together they reduce the annual grid purchased energy of the building from 360 kWh/m2 (based on above ground floor area) to 36 kWh/m2, a factor 10 reduction. Natural gas consumption was reduced by approximately 94% and grid purchased electrical consumption was reduced by approximately 81%. As a result of these energy savings, a factor 6.6 reduction (85%) in greenhouse gas emissions was also achieved. The goal of factor 10 could not be achieved only through energy conservation and the final design includes two solar water heating systems and grid-connected photovoltaic panels. These systems were modeled using RETScreen project analysis tools.Capital cost estimates and simple payback periods for each retrofit are also presented. The total cost to retrofit the building is estimated to be $3,123,000 and the resulting utility savings from the retrofits are approximately $150,000 per year. This is a factor 6.0 reduction (83%) in annual utility costs in comparison to the base building. While the typical response to proposing a “green” building is that financial sacrifices are required, there is also research available stating that operating in a more sustainable manner is economically advantageous. This research project adds to the “green building economics” debate by detailing savings and costs for each retrofit and ranking each retrofit that was proposed. The most economically advantageous mechanical system that was added to the building was energy recovery in the outdoor ventilation air. It should also be noted that there was already a glycol run-around heat recovery system in the building and even greater savings would have been obtained from installing the energy recovery system had this not been the case.While the goal of factor 10 required economically unjustifiable retrofits to be proposed, the majority of the retrofits had simple payback periods of less than 20 years (30 out of 49). This research shows that certain retrofits have highly desirable rates of return and that when making decisions regarding investing in auditing a building, improving energy efficiency, promoting conservation, or utilizing renewable energy technologies, maintaining the status quo may be economically detrimental. This would be especially true in the case of new building construction.



Heat Recovery, Energy Recovery, Mult-Unit Residential, Energy Consumption, Energy Efficiency, Apartment, High-Rise, Building Energy Audit, Solar Energy, Renewable Energy, MURB, Greenhouse Gases



Master of Science (M.Sc.)


Mechanical Engineering


Mechanical Engineering


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