This paper presents a case study of a neighbourhood low carbon energy system designed for five off-gas rural dwellings in the UK. The employment of the neighbourhood system aims to improve energy efficiency of the whole site, reduce dependency on heating oil or LPG for off-gas houses, maximize renewable energy usage on site, and minimize fuel poverty through affordable investments. System design is discussed and built on site survey, ongoing monitoring and validated modelling. Simulation is carried out in dynamic model HTB2. A ROI analysis is used to examine the long-term cost-effectiveness, taking into account any maintenance and replacement cost, degradation of system performance and discounting of money over time. The neighbourhood system scenario is compared with an alternative scenario of separate systems for individual houses, in terms of energy reduction, energy self-sufficiency, CO2 reduction and pay-back time. The simulation results indicate the designed optimal neighbourhood system can achieve similar self-sufficiency as that of a separate system scenario, with more than 70% of its electricity demand met by onsite electricity production. Both the neighbourhood system approach and the separate one can achieve carbon negative for the whole site, with the former contributing to 31% more carbon reduction than the latter. The neighbourhood system can be paid back within its lifespan, while the separate system approach can't. The payback time of the neighbourhood system can be reduced to 14 years if traditional bolt on PV system is used instead of building integrated PV. The outcome of the research demonstrated the affordability and replicability of the neighbourhood low carbon energy system, which can decrease fuel poverty, and meet government targets for CO2 reduction.

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This paper presents the results for the operating energy performance of the smart operation for a low carbon energy region (SOLCER) house. The house design is based on a ‘systems’ approach, which integrates the building technologies for electrical and thermal energy systems, together with the architectural design. It is based on the concept of ‘energy positive’ buildings, utilising renewable energy systems which form part of the building envelope construction. The paper describes how the building energy model HTB2, with a range of additional ‘plugins’, has been used to simulate specific elements of the design and the overall energy performance of the house. Measurement data have been used in combination with the energy simulation results to evaluate the performance of the building together with its systems, and identifying the energy performance of individual components of the building. The study has indicated that an energy-positive performance can be achieved through an integrative systems approach. The analysis has indicated that the house, under normal occupancy, needs to import about 26% of its energy from the grid, but over the year its potential export to import ratio can reach 1.3:1. The paper discusses the performance gap between design and operation. It also considers the contribution of a transpired solar air collector (TSC) to space heating. The results have been used to gain a detailed understanding of energy-positive performance.

This paper presents an evaluation of the economic and technical feasibility of a renewable-led low carbon house in the UK. A holistic systems-based approach to achieve energy positive house has been taken. Long-term economic and technical feasibility analysis have been carried out based on a validated thermal and energy model of the house. The economic analysis employs the Return on Investment (ROI) method and considers changes to government financial support and technology progress over time. Results show that the extra investment on the house, compared with that for building a standard social house of similar size, can be paid back within the system lifespan under both the old Feed-in Tariff and its proposed replacement with reduced financial support. Variants examined in the technical feasibility analysis include housing type, orientation and location. Results show that the house can be replicated to achieve an energy positive performance for all variant combinations. Among the variants, location has the highest impact on building performance including annual electricity import, CO2 emission and electricity self-sufficient ratio, with South UK performing better than North UK. This implies that more efficient or advanced technologies would be needed to achieve similar building or system performance in areas of unfavourable climate. The outcome of the research has demonstrated the affordability of the energy positive house, and the technical feasibility of its replication with different housing types, orientations and locations in the UK. This study supports the wide scale replication of this affordable systems-based approach in domestic building design and construction when incorporating appropriate technologies.

European governments have set ambitious retrofitting targets driven by the commitment to reduce the greenhouse gas emissions by at least 80% by 2050. The United Kingdom has the oldest housing stock in Europe, with over 2/3 of dwellings built before 1976, when building regulations started to include energy efficiency. This raises concerns over carbon emissions, health, comfort and running costs, and government’s set targets and initiatives for significant improvements. Deep retrofitting by using innovative technologies with respect to aesthetics has considerable and measurable benefits, while it can be a costly and challenging process. This study examines a combination of measures undertaken in a pre-1919 dwelling in south Wales, including reduction of energy demand and the application of renewable energy supply and energy storage. A whole house performance and a systems breakdown evaluation is presented comparing the pre and post intervention status. Both monitoring and modelling tools where used, and the performance gap is also discussed. An annual reduction of 34% in space heating and 78% in electricity import was monitored with an additional electricity export of 3217kWh. This represents a total annual cost saving of £1115, at 2019 UK gas and electricity prices. The total cost of the retrofit was £55K.