6.1 The Building as an Energy System
Modern buildings are complex structures; there are significant interactions among the various systems of which they are comprised. The energy auditor needs to look holistically at the building when recommending efficiency measures to ensure that these interactions are taken into account.
6.1.1. Energy interactions of building systems
Among the interactions that need to be considered are the following:
- A lighting retrofit from incandescent to fluorescent lighting, because of the improved efficiency, will reduce the internal heat gain of the building; therefore, in the heating season, the building heating plant may experience an increased load, and in the cooling season, the AC system will experience a decreased load.
- Because the AC system not only cools, but dehumidifies the building, the same lighting retrofit could result in a now over-designed cooling plant to operate less frequently to maintain temperature, but as a result, allow humidity to increase.
- Building envelope improvements to increase insulation and decrease infiltration will have effects similar to those noted above on the heating and cooling plant; also, reducing infiltration could require an increase in fresh air supply in order to maintain occupant comfort and meet indoor air quality standards.
- What are some other interactions that you need to consider?
6.1.2. The impact of measures on power quality, IAQ, and GHG emissions
Some efficiency measures may have negative impacts on some operational factors, as well as positive side-effects on others. The auditor needs to take both into account.
- Modern high efficiency lighting systems, while delivering more illumination for the same power consumption as incandescent fixtures, may introduce harmonics into the electrical distribution system, and adversely affect the operation of electronic equipment such as computers. Power quality effects such as this need to be considered when measures are recommended so that design features can be added to overcome them.