Estimation of energy savings potential through hydraulic balancing of heating systems in buildings

Abstract

Hydraulic balancing of heat distribution systems in buildings plays an important role in improving indoor thermal conditions as well as reducing energy consumption for space heating. Building energy models typically do not incorporate thermal comfort while it is essential for hydraulic balancing to do so. This paper proposes a methodology that assesses the impact of hydraulic balancing on the energy savings potential while ensuring thermal comfort of the occupants. The proposed methodology is composed of three parts, i.e. characterization, estimation and scenario analysis. First, we characterize indoor air temperature level of each individual flat in buildings belonging to the same central heating system to examine temperature variation among the flats. Second, thermal comfort under given indoor conditions is predicted by means of the PMV-PPD model (predicted mean vote-predicted percentage of dissatisfied) and the optimal indoor air temperature where most of the occupants feel comfortable is estimated. We calculate potential energy savings assuming that hydraulic balancing ensures ideal conditions where the indoor air temperature stays at the optimal level, thereby maintaining thermal acceptance of at least 94% of the occupants. A scenario analysis covering different types of occupant behavior allows to estimate the energy savings potential under different conditions. We test the applicability of the proposed methodology by applying it to a group of existing buildings in Geneva, Switzerland during the cold season. The case study demonstrates that there is an energy savings potential between 2% and 14%. We also discuss how the simulation results can guide practitioners operating hydraulic balancing programs.