This paper presents some of the results of an ongoing research project that examines the relationship between current building
practices and space heating in mid- to high-rise multiunit residential buildings (MURBs). The actual energy records and characteristics
of the building enclosure are analyzed in detail for 39 mid- to high-rise residential buildings constructed over the past
40 years, located within the Lower Mainland of British Columbia. Several of the buildings in the study underwent complete building
enclosure rehabilitations, primarily to address moisture damage, and this has provided an opportunity to examine the actual
energy savings resulting from enclosure improvements. The effective R-value for all building enclosure assemblies have been
calculated in detail and overall building R-values have been determined and compared to Standard 90.1 (ASHRAE 2007)
and other performance criteria. The magnitude and significance of air leakage on space heating has also been assessed.
Significant conclusions include the following:

• Space-heating and total energy consumption in high-rise condominium MURBs appears to have increased over the past
  30 to 40 years despite perceived improvements in energy efficiency.
• Building enclosure rehabilitations to address moisture damage have demonstrated measurable reductions in space heating
  loads. Further reductions would be possible if incentives were available to improve energy efficiency at the time of
  necessary enclosure repairs.
• The overall effective R-values of high-rise MURBS have improved very little over the past 40 years, and current practice
  still remains significantly lower than current expectation for low-energy consumption buildings.
• Individual metering is an essential component of managing energy consumption in MURBs.
• Air leakage control has improved due to increased attention to wall and interface detailing; improved window performance,
  however, is still below expectations for current standards and low-energy consumption buildings.
• Airflow within the buildings is an issue for energy consumption and underscores the need for internal compartmentalization
  of suites in MURBs.
• A better understanding of occupant behavior and how buildings are actually operated is needed in order to design more
  efficient buildings.

These conclusions also represent the best opportunities to improve building enclosure performance as part of achieving an
overall net-zero energy goal in multiunit residential construction.