Energy conservation opportunities related to improvements of the building envelope are generally easy to identify, but difficult to quantify in terms of potential savings. The reason for this is that buildings are dynamic structures, experiencing transient rather than steady-state heat flows.

The large thermal mass of most construction types in Pakistan (e.g., heavy masonry or concrete walls and roof decks) create a thermal lag in the transfer of heat between the outdoors and indoors. Tests conducted have indicated that the peak inside ceiling temperature may occur 4 hours or more after the peak outdoor temperature has been reached. An additional problem occurs in trying to estimate savings through reduction in infiltration or exfiltration. These sources of energy waste depend heavily on prevailing wind direction and are variable from moment to moment.

The general approach in the estimation of energy savings potential is through the use of computer building energy load simulation models. These models rely on detailed meteorological data and a fairly complex description of the building under consideration, including its dimensions, orientation, materials of construction, placement of windows in the building shell, interactions with the building's surroundings, and a number of other factors. The building simulation  models allow the impact of changes to one or more of the buildings construction details to be analyzed and compared to a base case. The computer simulation models carry out a complex series of calculations on an hourly basis to account for the various heat transfer mechanisms in the building and their interactions (e.g., building shell conduction, convection, and radiant heat transfer; solar heat gain through windows; heat transfer through infiltration, natural ventilation and mechanical ventilation; heat gains caused by the activities of building occupants; heat gains caused by the use of equipment in the building).

Low Cost Energy Conservation Opportunities

There are many energy conservation opportunities that can be implemented by simple changes in operating, maintenance, and administrative procedures. In conducting the preliminary energy survey, a number of these measures can be identified as follows:

• Improper alignment of windows and doors allows excessive infiltration.

• Ceiling/roof insulation is inadequate or has been water damaged.

• Weather stripping or caulking around windows, doors, conduits, etc. is worn, missing or broken, or damaged mortar allows infiltration of outside air.

• Excessive expanses of glass areas on exterior exist on exterior walls.

• Outside air leaks through mechanical ventilation systems.

MEConsult staff were attached with ENERCON's Building Energy Conservation Program throughout its various phases. Among other things the staff was responsible for conducting infiltration tests utilizing methods that, as yet, have no parallels in the local energy consultancy domain. Further, they were involved in the monitoring of key building energy data with the objective of utilizing it in a Building Energy Simulation computer program DOE-2.