UBC Graduate Research

Analysis and concept design for grey water heat recovery to preheat domestic water supply for multi-unit residential high rise building : a way to reduce energy consumption Rushya, Senthil Kumaran Vellore


An analysis of grey water in multi-unit residential buildings was performed followed by a concept design for deployment of the GWHR system with SITKA building as the case study. In MURBs, most of the energy is used for space heating and water heating. Energy conservation measures such as deploying GWHR system in the path of waste water drainages will help in reducing energy consumption in MURBs. A literature review was conducted to review different GWHR systems and also to review different water heating techniques in MURBs. The review indicated that most of the MURBs use boilers for their hot water needs and natural gas for heating up the water in boilers. Most of GWHR systems (from different manufacturers) are more or less similar in operation, effectiveness, size and cost. A concept design is proposed for deploying the GWHR systems for high rise MURB (SITKA) for effective capture of heat from waste grey water. Calculations for energy, dollar and GHG savings were made along with payback period for two different mass flow rates. It was observed that the calculations mostly depended on the mass flow rates of drained waste grey water. It was also noticed that when mass flow rates increase, energy, dollar and GHG savings also increase and the payback period decreases. The energy savings ranges from 27.91 GJ/year to 83.72 GJ/year; the dollar savings ranges from $150.69/year to $452.07/year; and the GHG savings ranges from 1.56 tonne of CO2/year to 4.69 tonne of CO2/year. The above values do not include deployment of GWHR systems for the shower drainages. It was concluded that GWHR systems need to be deployed for shower drainages for high energy savings and they could be deployed for other drainages if subsidies were given by the government for GWHR systems. For a worthwhile investment, one GWHR system can be installed for the whole SITKA building as the investment of one system can be covered by the energy savings obtained by deployment of one GWHR system. Disclaimer: “UBC SEEDS provides students with the opportunity to share the findings of their studies, as well as their opinions, conclusions and recommendations with the UBC community. The reader should bear in mind that this is a student project/report and is not an official document of UBC. Furthermore readers should bear in mind that these reports may not reflect the current status of activities at UBC. We urge you to contact the research persons mentioned in a report or the SEEDS Coordinator about the current status of the subject matter of a project/report.”

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