This research project was undertaken to review detailed energy and water consumption monitoring data which has been collected for 34 multi-unit residential buildings. The project used the data to determine annual energy and water consumption as well as hourly, weekly and monthly energy and water use patterns. Concurrent natural gas and electricity consumption is also detailed. An analysis was undertaken to determine if there was any correlation between the characteristics of the buildings and energy or water use patterns observed. The research revealed that significant variations exist in the normalized energy and water use from building to building and that patterns in the variations were difficult to predict based on building characteristics and occupancy type.

Energy used in residential buildings is a major energy use in Canada (21% of all energy) and presumably in most areas in the Northern hemisphere. A substantial fraction of this energy (24%) is used in multi-residential buildings. However, very little attention has been given to examining the patterns of energy and water consumption, let alone how they can be improved. This report suggests that significant savings and improvements in the efficiency of multi-residential systems are achievable, and this could go a long way toward reducing energy usage and fulfilling Canadian Kyoto obligations. Watershed Technologies Inc. and OZZ Energy Solutions Inc. have been monitoring energy and water usage in multi-residential buildings in the Toronto area since 1996. The present analysis looks at detailed (hourly) gas and electricity loads in 34 buildings and water consumption in 21 buildings over a two-year period from May 2001 to April 2003. An earlier report by OZZ documented the different physical features of these buildings and presented an overall summary and a preliminary analysis of gas, electricity and water consumption data along with daily and seasonal summaries. A more detailed analysis is offered in the present report. A new model is developed which describes the building's energy consumption for cooling and heating more effectively than the traditional degree-day model. The new model quantifies not only the changes in energy load per unit change in temperature but also its effective thermal capacity, the heating system overhead and system response to other weather factors, namely wind, relative humidity and solar access. More than two fold differences in the energy per unit area or water used per apartment unit among the buildings are observed. A study of seasonal and daily variability suggests that at least a part of these differences in the building energy efficiency can be attributed to poor or complete lack of energy management in many of the buildings. The data also suggests that in-suite electric heating is 2.5 times more efficient than central gas heating systems in multi-residential buildings. The same appears true of in-suite air conditioning, when compared to centralized cooling systems.

Implementing energy and water efficiency is a crucial consideration for today's property managers and building owners. Energy and water costs in multi-residential buildings can account for anywhere from 25% to 50% of total operating costs. While amendments to building codes and standards over the past 20 years have improved energy and water performance in newer buildings, over 50% of housing was constructed prior to 1980. Few of those have been upgraded to today's standards of energy efficiency. Improving energy and water efficiency can decrease operating costs, reduce maintenance fees, lower tenant turnover rates, increase the asset value of property, and extend the life of the building. CMHC, in partnership with the Ontario Ministry of Municipal Affairs and Housing (OMMAH), has developed a manual that details energy and water efficiency measures for existing multi-unit residential buildings. The document is based on a manual originally developed by the Ontario Ministry of Housing in the early 1980's. The new manual offers proven, current energy efficiency measures for the building envelope, mechanical, electrical, and domestic hot water heating systems. Both the User Guide and Technical Manual are designed to assist property managers in implementing an energy and water conservation program in mid- and high-rise residential buildings. They can be used to help organize activities, develop detailed energy and water conservation plans, and provide an understanding of which energy and water efficiency measures are best. The User Guide provides advice on how to manage activities, from conducting an energy/water preliminary assessment, determining appropriate conservation measures, estimating payback and the development of an energy/water plan. The Technical Manual outlines in detail more than 60 energy and water conservation measures for multi-unit buildings. Each provides basic details on assessing the viability of measures in relation to the specific requirements of buildings, as well as recommendations on integrating measures into ongoing maintenance, repair and/or renovation/retrofit work. Each measure can be used in isolation, in selected groupings, or integrated into any maintenance, repair and/or renovation/retrofit work on the building. Note: Individual energy and water efficiency measures have been placed on the CMHC high-rise website as the energy and water efficiency "Tip of the Week". The manual will form a part of the reference material for a series of energy management seminars being organized by the Ontario Non-Profit Housing Association in the spring of 2004.