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This paper presents an exploratory analysis of microgeneration installer businesses in the UK during a period of intense change in policies supporting microgeneration from 2010 to 2012. The research examines the influence of installer businesses on rates of uptake and standards of installation, and the interplay between business practices and the policy environment. The research developed new detailed datasets through a nationwide survey, to which 388 installers responded, and follow-up interviews with 22 installers. Focusing on solar photovoltaics and air source heat pumps installed in households, the results show the fundamental dependence of installer businesses on government financial incentives and on the quality assurance scheme in operation. Market confidence was compromised by the sharp reduction in the Feed-In Tariff (FIT) for residential solar PV in 2012 and long delays to the equivalent Renewable Heat Incentive for residential installations. Nevertheless, more modest FIT levels have reduced the risk of sub-optimal installations and inappropriate specification of microgeneration systems. The findings underline the need for consistent policy to allow installer businesses and their supply chains to develop and mature, and thus facilitate commercial deployment of microgeneration of high quality, raise its competiveness with incumbent forms of energy supply and contribute to decarbonisation goals. [ABSTRACT FROM AUTHOR]

The electrification of home heating is proposed as a low carbon solution in climate change action plans. It is therefore important to understand the energy efficiency and capability of heat pumps when deployed in the homes of end users. This paper presents a systematic literature review of Air Source Heat Pumps (ASHP) field studies. The papers are reviewed with respect to the field study focus, and analysed in terms of the field study design, and the analysis methodologies applied to the gathered data. The review finds three main areas of focus: defrosting management, ASHP system management, and ASHPs as smart grid demand response components. The review also identifies what ASHP data is publicly available to assist other researchers in building, testing and analysing ASHP efficiency models. Finally, future research topics on the use of ASHPs in home heating are identified. • Systematic Literature Review of ASHP Field Trials. • Three key themes identified: defrosting, whole ASHP system management, and ASHPs as smart grid components. • Variable range of Coefficient of Performance values in field trials. [ABSTRACT FROM AUTHOR]

• Forecast analysis of the behavior of air source heat pumps for the next 50 years for all climate zones. • The winter heating season is expected to shorten and the summer season to lengthen. • Winter operating hours will increase in very cold climates and decrease in temperate climates. • Rising temperatures will force air source heat pumps to work in extreme conditions for longer periods in hot climates. • Under extreme winter conditions, exceeding the TOL (operating limit temperature) occurs for an increasing number of hours. Climate change will impact the building sector, but the related consequences are not fully known, especially at energy system level. This paper investigates the effect of a changing climate on heat pumps, worldwide recognized as one of the most promising technology to decarbonize the building sector. Being highly dependent on outdoor temperature, the research aims to understand how air-source heat pumps (ASHPs) will perform within climate change depending on locations and scenarios. ASHPs are considered in several locations around the world selected to cover the climate variability of the Köppen-Geiger climate classification. Future projected climate scenarios to the years 2030, 2050, and 2070 are studied under three Representative Concentration Pathways (RCPs: 2.6, 4.5, 8.5) that reflect an increasing climate change severity. The forecast analysis is conducted in terms of ASHPs seasonal coefficients of performance, working hours, seasonal and annual energy consumption. Results show how a rising average temperature facilitates, in winter, the energy transition to the use of electric heat pumps to replace fossil fuels. However, differences are found among locations, scenarios, and RCPs. The research illustrates how the two effects of heating decrease and cooling increase offset or whether one seasonal consumption prevails and where this occurs. The general trend foresees a noteworthy reduction of winter energy consumption in all climate zones. Higher decreases are found for RCP 8.5 compared to RCP 2.6 and RCP 4.5 scenarios, for both radiant floor panels and fan coils, with most variations in Hanoi (-48,24 % in 2070) and Cairo (-39,59 % in 2070). Concurrently, a major rise is estimated in cooling consumption in almost each climate zone, with wider differences within RCP 8.5. In this scenario, the increase in summer energy consumption is more extreme, ranging from a minimum in Singapore (+4.20 %) and Mombasa (+4.66 %), to a maximum in Anchorage (+87.31 %), Reykjavik (+49.89 %) and Lethbridge (+56.53 %). This increase is only partly offset by the reduction in winter energy consumption, with an overall net increment in the forecasted building's energy consumption. [ABSTRACT FROM AUTHOR]

As a widely used technique, vapor injection plays an important role in air source heat pumps (ASHPs) which operate across a wide range of ambient temperatures. The one of primary solutions has been reported to be vapor injection based on flash-tank (FT) and intermediate heat exchanger (IHX) loops respectively. In this paper, vapor injection and its two typical configurations are experimentally investigated in an ASHP prototype. The results show that in the vapor-injection based ASHPs, the performance of FT based ASHPs is better than that of IHX based ones, and injected vapor improves mass flow rate and distribution of working fluid, with a hidden decreasing effect of exhaust entropy. In order to explore theoretical reasons, a whole system model is presented that quantifies performance enhancement potential of FT based and IHX based ASHPs respectively. The calculation results show increased refrigerant mass flow rate, its optimum distribution, and moderate injected vapor entropy contribute to performance improvement of vapor-injection based ASHPs. Further, we also visualize synergy between refrigerant mass flow and injected entropy from perspective of negentropy. At the negentropy level, FT based rather than IHX based loop brings higher heating capacity and efficiency, which is consistent with measurements from experimental research. • Refrigerant mass flow has a significant incentive effect on ASHP performance. • The positive impact of injected entropy toward ASHP performance is demonstrated. • The synergy between mass flow and injected entropy is dominant in RI loops. • The impact of flash-tank based and sub-cooler based RI is quantitatively measured. [ABSTRACT FROM AUTHOR]