Decentralized Drain Water Heat Recovery: Interaction between Wastewater and Heating Flows on a Single Residence Scale

Abstract

This paper studies the potential for drain water heat recovery on a single residence scale, showing its interaction with the space and domestic hot water heating system. The article performs a Monte Carlo simulation based on measured wastewater characteristics, and heat consumption data provided by the Building Energy Ratings database. It shows the necessity of a back-up heating system, on average between 8 and 42% of the demand can be met by recovered heat. This would signify a reduction in GHG emission varying between 7.6 and 22%, but would increase costs ranging from 120 to 130%. Using a hot water reservoir increases the share of recovered heat in the mix, reducing GHG emissions and costs. However at current traditional heating prices, the drain water heat recovery system for a single residence is not financially competitive with traditional systems, showing the need for different strategies.