11 September 2018 The most acceptable method of water heating for Badock – a University of Bristol Hall of Residence. A Thermal and Financial Model Naomi Knight - University of Bristol - 2013-2016

11 September 2018 Background Hot water accounts for 18% of domestic energy use in the UK. Halls of Residence are unique University of Bristol target - 38% reduction in emissions.

11 September 2018 Aims and Objectives Find the cheapest method of heating water in Badock Hall of Residence, with consideration of the environmental impact of the system. Objectives: Undertake site visit to identify current systems and suitability for alternate systems. Produce thermal model of the current system and a solar thermal system. Produce financial model of both systems Compare results with those of Yingpei Gao

09 May 2016 Current System Simple schematic of current electric immersion heater system.

Current System (2) System with WWHR and insulation Current system 11 September 2018 Current System (2) System with WWHR and insulation Current system Varying tank temperature over the course of the day for different system configurations

09 May 2016 Solar Thermal Varying tank temperature over the course of the day for different system configurations

Solar Thermal (2) Data set Find time Panel and HX heat addition 09 May 2016 Solar Thermal (2) Data set Find time Panel and HX heat addition Electricity and heat loss Left: simple flow chart of thermal matlab model, Above: Stratified tank model, water returns via manifold diffuser. Mass and Heat balance for tank

09 May 2016 Solar Thermal (3) Monthly solar fractions for each system. 33% - 41% annual solar fraction - increases to 35% - 44.7% for PV pumping.

Includes energy tariffs – FIT and RHI - and maintenance costs. 09 May 2016 Financial Model Includes energy tariffs – FIT and RHI - and maintenance costs. Solar thermal ROIs £102, 000 and £146,000. (Highest ROI for small FPC system with PV pump.) ASHP ROI £200,000.

Financial Model (2) Do nothing scenario ASHP 09 May 2016 Financial Model (2) Do nothing scenario ASHP Annual cost of each system configuration, including amortised CAPEX and predicted maintenance costs.

Environmental Impact Gas emissions higher than grid emissions ASHP 09 May 2016 Environmental Impact Gas emissions higher than grid emissions ASHP Annual CO2 emissions for each system, 70% reduction for solar thermal and 90% reduction for ASHP.

09 May 2016 Conclusions Mitsubishi ASHP is the recommended heating method. (Limited) Potential for solar thermal Worst possible outcome – is do nothing.

Thank you d Any Questions? 09 May 2016 Thank you d Any Questions?