Potential retrofits in office buildings located in harsh Northern climate for better energy efficiency, cost effectiveness, and environmental impact

Abstract

The current study evaluates the potential measures for enhancing energy efficiency in a commercial building application. It is directed towards addressing Northern climate conditions that are scarce in literature. To highlight the recommended measures, a case study involving a two-storey office building that was built in the late 1970s in Ottawa, Canada is presented. As typical for commercial buildings in Northern climates, building heat is provided by natural gas. Cooling, lighting, and other building needs are supplied by electricity. The building current operational condition deviates from what is recommended by the building code. The authors were consulted to propose energy efficiency measures for the building. The building was simulated using the eQuest software. Verification of the simulation results was performed against historic site data. The model highlighted several parameters that can reduce energy consumption and greenhouse gas emission. Major influencers on energy consumption were: building envelope, water heating system, and building air tightness. Amongst them, increasing building air tightness is the cheapest to implement. On the other hand, the parameters that are functions of occupancy had minor effect on the reduction of energy consumption. A detailed economic analysis has been conducted to evaluate the feasibility of the proposed retrofit strategies. The analysis quantified that the wall, roof insulation, boiler upgrade and building air tightness have a high impact on reducing energy consumption by more than 52%. The improvements have the potential to reduce the emissions by around 82 tons of CO2 per year. The return on investment was found to be 5 years. The incorporation of renewable energy to the building was also investigated. Solar energy is not commonly integrated in cold climates in most of the reported research. For the current study, a solar heating system was installed to supply needed hot water and a PV system is used for electricity generation. This causes the payback period to increase to 5.6 years if solar water heating is added and to 9.1 years with solar water heating and photovoltaic integration. Debt ratio and interest rate have detrimental effect on return on investment for the project. The results of the current study are valuable recommendations for people interested in retrofitting commercial applications in Northern climates.