Low Temperature Energy Recovery Designs

Abstract

This article discusses low temperature energy recovery systems that are being installed on three Federal buildings in the Washington, DC, area. The three projects discussed use simple systems that deliver low cost heat to buildings in innovative ways. Each uses a source of low temperature heating available from within the building to reduce fossil fuel use. One system recovers heat from the ventilation return air to heat water for the hydronic reheat loop serving variable air volume boxes in the building. The second system recovers heat from an attic space below a plywood roof deck covered with asphalt shingles to heat a domestic hot water loop for a barracks. The third system recovers heat from the solar re-roofing of a building to supply heated air for swimming pool heating and for a heating, ventilating, and air conditioning system. The purpose of this article is to demonstrate the versatility of these low temperature heat recovery systems.