Lighting Heat Gain Parameters: Experimental Results (RP-1282)

Abstract

The ASHRAE cooling load procedures employ a simple lighting heat gain model to account for the energy dissipated by lights. The simple lighting heat gain model requires knowledge of the conditioned space/ceiling plenum split in order to estimate how much of the lighting energy is transmitted to the conditioned space as heat gain. The model also requires the radiative/convective split in order to estimate how much of the lighting heat gain in the conditioned space is transferred as radiation and as convection. Experimental measurements of the lighting heat gain parameters were conducted for a range of contemporary luminaires in a full-scale test facility under realistic operating conditions. This paper presents experimental results along with their estimated uncertainties. The paper also discusses effects of various test parameters on the measured data. It is found that the lighting heat gain parameters are typically more sensitive to the luminaire type and the room airflow rate than to other parameters. Using different luminaires can result in an increase of 0.20 for the space fraction, which is higher than the typical uncertainty in the space fraction. Similarly, doubling the airflow rate can cause an increase of as much as 0.30 in the space fraction. On the other hand, other test parameters typically cause changes in the lighting heat gain parameters that are smaller than experimental uncertainties. This paper presents design data and application guidelines based on these findings. A companion paper discusses in detail the experimental method used to determine the lighting heat gain parameters.