• Energy Research

Building ‘zero carbon’ homes will be essential for achieving the carbon reductions within industrialised countries required to meet their commitments under the 2015 Paris Agreement on climate change. Such high performance buildings may need a combination or ‘cluster’ of micro-generators to be installed, such as a heat pump to provide heating and a solar photovoltaic (PV) array to produce electricity. When sized and installed appropriately, these technologies have lower emissions than the conventional systems they displace (centralised grid electricity and gas-fired boilers). However, if the ‘embodied’ energy and carbon is not recouped from that saved during the lifetime of the micro-generator, then there is no net saving overall. This study therefore assesses a range of clustered micro-generators using an ‘integrated approach’ that combines energy analysis, environmental life-cycle assessment, and an indicative financial appraisal. Eight clusters of micro-generators were designated to meet the heat and electricity requirements of five different dwelling types, each one specified to two different UK performance standards (2006 building regulations and a zero-carbon specification). For these 80 scenarios, various combinations of heat pumps with solar hot water and/or PV systems yield the most attractive performance metrics with all of the clusters having energy and carbon paybacks (4.5–5.5 and 5.0–7.0 years respectively) within their operational lifetimes, and would hence create net savings overall. But the clusters were generally found to have unattractive financial payback periods (50–80 years), although this result will be sensitive to the discount rate and prevailing energy prices and support mechanisms. The focus is on the use of clustered micro-generators in the context of UK transition pathways to a low-carbon economy out to 2050, but the lessons learned are applicable to many industrialised countries.

Approximately 38% of current UK greenhouse gas emissions can be attributed to the energy supply sector. Losses in the current electricity supply system amount to around 65% of the primary energy input, mainly due to heat wasted during centralised production. Micro-generation and other decentralised technologies have the potential to dramatically reduce these losses because, when fossil fuels are used, the heat generated by localised electricity production can be captured and utilised for space and water heating. Heat and electricity can also be produced locally by renewable sources. Prospects and barriers to domestic micro-generation in the UK are outlined, with reference to the process of technological innovation, energy policy options, and the current status of the micro-generation industry. Requirements for the main technology options, typical energy outputs, costs to consumers, and numbers of installed systems are given where data is available. It is concluded that while micro-generation has the potential to contribute favourably to energy supply, there remain substantial barriers to a significant rise in the use of micro-generation in the UK.

The validation after HERS BESTEST contains a base model for a single zone, single storey building isolated in Colorado (USA). This base model (ID L100A) is then modified in a series of scenarios targetting different building properties, like glazing ratios, insulation levels, or shading conditions (IDs L110A to L324A and P110A to P150A). The examples are domestic buildings in the UK built with a desire to deliver a space heating demand better than the average of the national stock. These houses are described with the information that would be typically available early in the design process, following a first sketch of solutions that is meant to be influenced with ZEBRA. The dataset corresponds to (1) the ZEBRA tool, (2) its validation and (3) built-in examples. The ZEBRA tool is a novel, super-reduced, pedagogical model for scoping net zero buildings. The validation is after ASHRAE Standard 140-2017 for space heating demand intensity after HERS Bestest (Judkoff & Neymark 1995). The built-in examples are domestic buildings located in the UK and are described in the PDF files and implemented in ZEBRA. The ZIP file contains a blank version of the ZEBRA tool; a readme file; a folder containing example tasks (as PDF files) and solutions using the ZEBRA tool; and a folder containing a validation suite for the tool. The data is stored in plain-text files (either CSV or MD files, encoded in UTF-8) and spreadsheets (xlsx, Microsoft Excel 365, Version 2107 Build 14228.20226).

This dataset reflects our two-stage investigation into the stakeholder perceptions of Active Buildings. In the first stage, we collected thoughts on the future of the built environment through a series of online focus group discussions with 30 industry experts. In the second stage, we quantified the ideas that arose from the first stage through an online survey of 30 academics and researchers. The recently launched Active Building Code (ABCode) offers guidance on minimising the environmental impact of the next generation of buildings termed Active Buildings (ABs). This dataset reflects our two-stage investigation into the stakeholder perceptions of ABs and, in particular, their statistical analysis using a logistic regression model in R. Further relevant documentation may be found in the following resources. Nikolaidou, E., Walker, I., Coley, D., Allen, S., and Fosas, D., 2022. Going active. CLIMA 2022 conference, 2022: CLIMA 2022 The 14th REHVA HVAC World Congress. Available from: https://doi.org/10.34641/CLIMA.2022.325. Additional information can be found in the associated paper "Going active: How do people envision the next generation of buildings?'', included in the CLIMA 2022 Conference Proceedings.

In most industrialized countries, the buildings sector is the largest contributor to energy consumption and associated carbon emissions. These emissions can be reduced by a combination of energy efficiency and the use of building integrated renewables. Additionally, either singularly or as a group, buildings can provide energy network services by timing their use and production of energy. Such grid-aware or grid-responsive buildings have been termed Active Buildings. The recent UK Government investment of £36m in the Active Building Centre is a demonstration that such buildings are of considerable interest. One problem with the concept, however, is that there is no clear definition of Active Buildings, nor a building code to design or research against. Here we develop and test an initial novel code, called ABCode1. It is based on the need to encourage: (i) the minimisation of energy consumption; (ii) building-integrated generation; (iii) the provision of grid services; and (iv) the minimisation of embodied carbon. For grid services, we find that a lack of a precise, quantifiable measure, or definition, of such services means that for the time being, theoretical hours of autonomy of the building is the most reasonable proxy for these services within such a code. Practical application Buildings have a special role in the transition to a sustainable energy infrastructure and a decarbonised society. They can become an active part of energy networks by leveraging strategies and technologies that are already available, but are not yet articulated in an integrated scheme that facilitates their uptake at scale. This work provides a review of the issues and opportunities, and introduces a practical framework aimed at helping designers and researchers study and deliver such buildings, and in particular the buildings that will form the exemplars in the first wave of Active Buildings.

Buildings in the Global South are expected to drive a tripling of global cooling energy demand by 2050. In countries such as India, growth in energy use far outstrips growth in population, often to the ratio 3:1. While several building-level technologies exist that could help reduce peak and total demand, the technologies, or combination of technologies, that would offer the greatest peak reduction in the range of climates in the Global South is unknown as previous work has focused on mid latitudes. Hence, we use computer simulations to study, for the first time, six different cooling-driven peak-shaving technologies covering 19 different climates in the Global South. Using Latin Hypercube Sampling to account for the uncertainties arising from building variants and technology performance, we conduct a total of 266,000 annual hourly simulations. While thermally activated building systems and phase change materials deliver the largest reductions in peak and total demand, water storage is the most consistent in reducing the peak, yet had a possible increase in annual demand. We also develop technology combinations, or “recipes”, which suggest that the range of attainable peak and total demand reduction is between 19% - 95% and 20% - 99% respectively, depending on the climate. Given the scale of the potential reduction, our results justify the investment in such technologies by governments and others to deliver major reductions in energy demand and peak load in the Global South, but if incorrectly designed, it is clear they may result in reduced energy security and increased carbon emissions.

To assess the potential benefits and impacts of circular bio-based buildings, life cycle assessment (LCA) is a valuable method to identify systems or elements that have negative effects on the environment during the whole building life. To achieve low carbon buildings, LCA should be performed during the early design stage of buildings, to influence the choice more environmentally led solutions. In this paper, LCA was used during the early design stage of a circular bio-based wall panel prototype to guide the decision-making process for the improvement of the panel’s design. A cradle-to-cradle life cycle assessment was performed to compare the circular wall panel against other prefabricated wall panels, assembled using common construction materials and techniques. Results indicated that a circular design and some bio-based materials are not always synonymous with low environmental impacts.The first iteration of the circular panel had a GWP100 of 231.1 kgCO2e/m2 in the base case with one life cycle. This compared to 116 kgCO2e/m2 and 181 kgCO2e/m2 for the timber and steel frame panels respectively. The LCA was able to identify materials and components which contribute most significantly to the panels environmental impact. The identification of highly impacting materials in the initial panel design, LCA was used to guide the re-designof the circular bio-based panel. From investigating alternative materials for the insulation, cladding and internal substrate the environmental impact of the new design of the circular panel was lowered to 122 kgCO2e/m2. This research demonstrates how LCA can be used in the design process to reduce carbon emissions in circular buildings by using bio-based materials.

Thermodynamic ( energy and exergy) analysis can give rise to differing insights into the relative merits of the various end-uses of electricity for heat and power. The thermodynamic property known as ‘exergy’ reflects the ability to undertake ‘useful work’, but does not represent well heating processes within an energy sector. The end-use of electricity in the home, in the service sector, in industry, and the UK economy more generally has therefore been examined in order to estimate how much is used for heat and power, respectively. The share of electricity employed for heat and power applications has been studied, and alternative scenarios for the future development of the UK energy system were then used to evaluate the variation in heat/power share out to 2050. It was found that the proportion of electricity used to meet these end-use heat demands in the three sectors examined were likely to be quite high (∼50–60%), and that these shares are insensitive to the precise nature of the forward projections (forecasts, transition pathways or scenarios). The results represent a first indicative analysis of possible long-term trends in this heat/power share across the UK economy. Whilst the study is the first to consider this topic within such a timeframe, some of the necessary simplifying assumptions mean there are substantial uncertainties associated with the results. Where end-use heat demands are met by electricity, energy and exergy analysis should be performed in parallel in order to reflect the interrelated constraints imposed by the First and Second Laws of Thermodynamics. An understanding of the actual end-uses for electricity will also enable policy makers to take account of the implications of a greater end-use of electricity in the future.