Reducing Hot Water Energy Consumption in Existing Buildings David Micallef Technical Marketing Manager Rheem Australia Pty Ltd
Reducing Hot Water Energy Use • Sources of energy use • Traditional methods of providing hot water • New options • Considerations for each option • Signature projects • Questions
Reducing Hot Water Energy Use • Sources of Energy Use – Domestic Hot Water • • • •
Restrooms Showers Kitchenettes Cleaners sinks
– Heating – Ring Main – Heating Plant Losses
Reducing Hot Water Energy Use • Traditional methods of providing hot water Boilers with DHW calorifiers (oil or gas) for combined heating and hot water Dedicated gas or electric centralised plant Localised electric water heaters and boiling water units
Reducing Hot Water Energy Use • New Options – Centralised solar • with gas or electric in series boost
– Centralised heat pump – High efficiency gas boilers – Co and Tri-generation
Reducing Hot Water Energy Use • Solar Considerations – Small scale Technology Certificates (was RECs) – Available roof and plant room space – Access for plumbing infrastructure – Shading of collectors – Aesthetics – Ring main recirculation – Frost
Reducing Hot Water Energy Use • Be wary of collector efficiency claims Solar irradiance G=800W/m2
1.0 0.8
0.8
0.6
0.6
0.4
0.4
0.2
0.2
0.0
0.0 0
Reference
0.02
0.04
0.06
Gross Aperture
Typical Flat Plate
0.08
Solar irradiance G=800W/m2
1.0
Tm
Absorber
0.02
0
Reference
0.04
0.06
Gross Aperture
0.08
Tm
Absorber
Typical Evacuated Tube
Reducing Hot Water Energy Use • Heat Pump Considerations – 3 phase availability – Plant room space / ventilation – Locate near a source of heat energy – Access for plumbing infrastructure – Not eligible to generate STC’s in commercial applications
Reducing Hot Water Energy Use • Condensing Boiler Considerations – Condensing occurs below approx 55oC – Australian systems designed for 80oC/60oC – Treatment of condensate Thermal Efficiency vs. Return Water Temperature for – Condensing Water Heaters
100
Low Fire
98
Mid Fire
Thermal Efficiency %
96
High Fire
94 92 90 88 86 84 15:C
25:C
35:C
45:C
55:C
65:C
Return Water Temperature Australia 20⁰C ΔT
75:C
85:C
95:C
Reducing Hot Water Energy Use • Co-Generation Considerations – Compare the waste heat output of the plant with the peak and daily demand hot water requirements – Determine the amount of DHW contribution required – Storage depends on the ratio of waste heat recovery versus peak demand contribution and available plant space
Flagship Projects Saadiyat Island – United Arab Emirates Construction Workers Quarters • 85 Commercial Solar systems • Providing over 2 millions litres of hot water at 38oC per day for construction workers
Flagship Projects Saadiyat Island – United Arab Emirates • 3,500 Bt solar collectors • 85 Heat Store storage tanks • Electric in tank boosting
Flagship Projects Gorgon Project – Barrow Island, WA • LNG mining project • Accommodation for 3,000 workers • Environmentally sensitive design
Flagship Projects Gorgon Project – Barrow Island, WA • Heat Pump System – 76 blocks each housing 40 people – 2 Commercial Heat Pumps, 5 storage tanks per block
Questions?
Thank you
