2016 ASHRAE Annual Conference

Energy retrofits provide an economically attractive solution to reduce the carbon footprint of existing buildings. However, indoor environmental quality and occupant comfort are often overlooked in the retrofit process. In this paper, we present the results of pre-retrofit monitoring of several multi-unit residential buildings in Toronto, Canada. The temperature, relative humidity and mean radiant temperature were measured in over 70 units across seven social housing buildings (built between 1960 and 1980) currently undergoing an energy retrofit process. Occupant thermal comfort was estimated using the Graphic Comfort Zone Method outlined in ASHRAE Standard 55-2013 and excess moisture was calculated as the vapour pressure excess during non-air conditioning periods. The major finding was that on average, the units were uncomfortable more than 70% of the time, with overheating being the main cause of discomfort. Location within a building (e.g., upper vs. lower floors) and building-specific effects showed little impact, although there was a weak seasonal effect with more overheating in the winter and spring. These findings are consistent with an occupant survey taken early in the project.  There was no consistent evidence of excess moisture, although this may be due to the observed overheating in the units. The results were used to inform the energy retrofit design process and are currently being monitored to ascertain how the retrofits affect occupant comfort in these buildings.

Advances on manufacturing processes and the use of new materials are increasing the efficiency and reducing the cost of energy efficient and renewable energy technologies to a point that their deployment will reach desired levels for the sake of energy security and environmental concerns. Along these advances, the demonstration of the cost-effectiveness of this technology is vital to educate people and promote deployment of these technologies. In this sense, at the University of Texas at Tyler, two research and demonstration houses were built. House #1 is a conventional design with some advanced features, and House #2 has more advanced design features. In this study, House 2 is considered, which has relevant characteristics such as net-zero energy with 7.4 kW of solar photovoltaic system, advanced wall framing with open-cell foam insulation (R-24), unvented attic with open-cell foam insulated roof deck (R-24), vinyl-frame windows with double-pane, low-E glass (U=0.33, SHGF=0.23), ducted single-split system in attic (19.0 SEER, 9.0 HSPF), high solar reflectance shingles, and heat pump water heater. Since building energy performance depends on many factors, different scenarios or design characteristics can be assessed by using an energy model. In this study, the software OpenStudio is used to develop a model for House #2. OpenStudio, developed by the National Renewable Energy Laboratory, is a user interface for the well know whole building energy simulation engine EnergyPlus. This paper shows the more relevant steps on model development including definition of the constructions in the model for the walls and roof, development of performance curves for the air source heat pump installed in the house, roof elevations development technique, and weather file. As a means of validation of the model, energy consumption from the model is compared against utility bills data in a calibration approach that is available in the software. The model is used to evaluate some design parameter that can reduce energy consumption during one season (cooling or heating), but increasing energy consumption during the other, such as the high solar reflectance shingles and the use of a heat pump water heater.