Increasing the energy efficiency of buildings Chris Cirone PhD Candidate, Agricultural and Biological Engineering

Hot Water Heater Mixing Valve Cold Water Supply Drain Water Shower Billable Energy Hot Water System—How it Works Shower drain water contains 80-90% of the thermal energy imparted by the hot water heater.

Energy Flow Diagram for Shower Water Primary Energy Conversion and Distribution Losses Losses to the Environment Heater Conversion and Storage Losses Hot Water Distribution Losses Losses Enjoyed by User Losses due to Evaporation Losses to Building Drain Lines Water Heating Electricity Generation 3

Waste Heat Recovery from Shower Water Hot Water Heater Heat Exchanger Thermostatic Valve Cold Water Supply Drain Water Shower 4

Heater Conversion and Storage Losses Primary Energy Conversion and Distribution Losses Electricity Generation Energy Flow Diagram for Shower Water Primary Energy Conversion and Distribution Losses Losses to the Environment Heater Conversion and Storage Losses Hot Water Distribution Losses Losses Enjoyed by User Losses due to Evaporation Losses to Building Drain Lines Electricity Generation Losses Recuperated by Heat Recovery Water Heating with Drain Water Heat Recovery (DWHR) 5

Vertical Recuperators 6 Vasile & Vasile (1986) Commercialized Independently tested by several labs, however most Natural Resources Canada at the forefront of this effort. (Zaloumn et. al. 2007) Independent Testing

Benefits of Drain Water Heat Recovery Reduced utility bill for water heating Reduces carbon footprint Typically positive returns on investment (ROI) Increased hot water capacity for water heater Increases available hot water duration (storage heaters) Warmer supply temperatures (tankless heaters) Allows for smaller hot water heater to be installed Can limit the energy throughput and increase service life of heating equipment Reduce peak electrical demands

What’s holding us back? Economic benefit is directly felt only by energy consumer Property owner is not necessarily the energy consumer rental properties neighborhood developers Length of ownership does not justify the investment. Lack of public knowledge regarding the technology Limited independent source performance data long-term performance data field studies to verify laboratory results secondary benefits not well understood Limited financial analysis to support the investment decision Lack of tradesperson knowledge regarding technology Potential plumbing code restrictions Limited or non-existent municipality incentives Energy prices are too cheap to justify the capital cost Cost-prohibitive retrofit Unit not compatible with house type.