The efficient collection and long term storage of solar energy in the UK, using air as the working fluid

This thesis describes the results of four years work on the design, construction, testing and evaluation of a high performance air heating collector designed to supply heat to a communal interseasonal store, which could heat many houses all the year round in the U.K. Interseasonal storage utilizing a pebble bed was investigated but shown to be costly both in terms of money and energy. The performance of medium to high temperature storage is shown to improve with high performance collectors. The level of insulation specified in the 1978 Building Regulations is found to be inadequate for solar heating with long and short term storage, because it is more economic to add more insulation than to install solar heating. While investigating the interseasonal storage of solar energy in pebble beds, data on the design and operation of air heating solar collectors was found lacking. Therefore the development and testing of both a high and low performance solar air heater was undertaken. The standard methods of testing collectors and in particular high performance collectors are shown not to provide an adequate method of comparing the daily efficiency of various types of collectors. Methods of testing air collectors are presented under transient conditions more representative of collector operation in the U.K. The parameters affecting high performance collectors are examined, in particular the reduction of heat loss between cover and absorber, and the effect on performance of diffuse and transient radiation. Results are also presented for testing a low cost plastic collector

Building energy use in COVID-19 lockdowns: did much change?

The UK national lockdowns introduced to prevent the spread of COVID-19 had huge impacts on daily lives, as people were largely confined to their homes. It could be expected that residential energy use would drastically increase while non-residential decreased, however the picture is not so clear. In this paper three complementary datasets on different scales are used to explore changes in building energy use during two national lockdowns (spring 2020 and winter 2021): the complete building stock of Great Britain, a sample of ~1000 residential buildings, and a sample of ~24,000 residential boilers. Energy signature analysis was used for the building data to estimate the changes in energy consumption for space heating and otherwise, with the boiler data able to separate space and water heating and explore changes in these. In the 2020 lockdown residential energy consumption for water heating and appliances increased, with decreased use for heating, resulting in a reduction in total energy use during the heating season. In the 2021 lockdown total energy consumption changed little, however a decrease in the use of gas space heating was observed. These residential changes counteracted any non-domestic changes, resulting in little difference in national energy consumption

The over-prediction of energy use by EPCs in Great Britain: A comparison of EPC-modelled and metered primary energy use intensity

This analysis compares the difference between the Energy Performance Certificate (EPC)-modelled and smart-meter measured annual energy use on a like-for-like basis in 1,374 gas-heated British households from the Smart Energy Research Lab (SERL) Observatory. EPCs and metered energy use were converted to primary energy use intensity (PEUI) to provide a comparison of the same quantity for the first time. We show that EPCs predict significantly more energy use than metered in homes in Great Britain. EPC bands A and B show no statistically significant difference, but all other bands show a significant gap which increases as EPC rating worsens. The PEUI gap widens from -26 kWh/yr/m2 (-8%) for band C to -276 kWh/y/m2 (-48%) for bands F and G. Unlike previous research, we show that the difference persists in homes matching the EPC-model assumptions regarding occupancy, thermostat set-point and whole-home heating; suggesting that occupant behaviour is unlikely to fully explain the discrepancy. EPCs are a core tool in the residential energy sector, and the gap between EPC-modelled and metered energy use could have a significant impact on policy, research, and industry. Future research should investigate disaggregated components of energy use, the underlying thermal model, and assumptions regarding building characteristics