When the STANDARD team assigned to compute energy savings and quotations appraises the cost of a project, it often finds it necessary to calculate the cross-effect of an energy study in order to obtain a precise evaluation of the annual savings following a lighting conversion. But what factors are evaluated when calculating these cross-effects?
To discover the savings associated with a lighting conversion, we need to do more than simply estimate the difference in wattage before and after the installation of new luminaries; true savings are often far lower than this figure might lead us to believe. In point of fact, lighting systems produce heat, which contributes to the heating process during winter months, but can be harmful to air conditioning during the summer. This is what we call a “cross-effect”; it needs to be taken into consideration when computing energy savings. For example, a lighting energy savings program will result in a reduction of heat given off by lamps. This causes an increase in heating needs in winter and a lowering of air conditioning needs in summer.
A Multitude of Cross-Effects
Cross-effects vary according to a number of factors: the building’s insulation, its geographic position, and its ventilation, the ceiling height, heat recovery as well as the building’s purpose and its heating source.
An good example of the factoring of cross-effects in the choice of luminaries is the arena of a municipality. A cooling system freezes the ice of the arena and thus, uses a significant amount of energy; by the same token, the lighting system of this facility diffuses heat that must be counteracted by the use of a refrigeration system. With the installation of an efficient lighting system, the municipality can expect a decrease of operating costs; it can also expect a reduction of the refrigeration’s energy costs as the unit’s compressors will require less power.
Hydro Québec has implemented a program to support energy efficient projects; it takes the cross-effects into account in the lighting industry. To learn more about this program consult the “effets croisés en éclairage” on the Hydro Québec Website. At STANDARD, we have a dedicated team of people whose job is to calculate energy savings on lighting conversion projects. Please don’t hesitate to contact us to learn more about this factor, and ask for a free estimate.