Steven K. Firth

Challenges for capturing and assessing initial embodied energy: a contractor’s perspective

Initial embodied energy includes energy use during material, transportation, and construction life cycle phases up to project practical completion. Contractors have an important role to play in reducing initial embodied energy levels due to their significant involvement in preconstruction and onsite construction activities. Following an extensive literature review a comprehensive framework was designed to highlight the significance of initial embodied energy levels relative to specific construction packages, activities and subcontractors. This framework was then applied to a new UK industrial warehouse project using a case study approach. Capturing information from a live project during the entire construction phase helped highlight the practical challenges inherent when capturing and assessing initial embodied energy levels. A series of contractor current practices was reviewed to determine their compliance with the framework requirements. The findings revealed that the ground and upper floor, external slab and frame were the most significant construction packages in terms of embodied impacts. Many challenges embedded within the contractor’s current practices in terms of data detail, legibility, and terminology were also revealed. The framework provides a practical approach for initial embodied energy assessment which can readily be adopted by contractors to help highlight opportunities to increase efficiency.

The potential for bioenergy crops to contribute to meeting GB heat and electricity demands

The paper presents a model system, which consists of a partial equilibrium model and process‐based terrestrial biogeochemistry models, to determine the optimal distributions of both Miscanthus (Miscanthus × giganteus) and short rotation coppice willow (SRC) (Salix. viminalis L. x S. viminalis var Joruun) in Great Britain (GB), as well as their potential contribution to meet heat and electricity demand in GB. Results show that the potential contribution of Miscanthus and SRC to heat and electricity demand is significant. Without considering farm‐scale economic constraints, Miscanthus and SRC could generate, in an economically competitive way compared with other energy generation costs, 224 800 GWh yr−1 heat and 112 500 GWh yr−1 electricity, with 8 Mha of available land under Miscanthus and SRC, accounting for 66% of total heat demand and 62% of total electricity demand respectively. Given the pattern of heat and electricity demand, and the relative yields of Miscanthus and SRC in different parts of GB, Miscanthus is mainly favoured in the Midlands and areas in the South of GB, whereas SRC is favoured in Scotland, the Midlands and areas in the South of GB.

Spatial mapping of building energy demand in Great Britain

Maps of energy demand from buildings in Great Britain have been created at 1 km square resolution. They reveal the spatial variation of demand for heat and electricity, of importance for energy distribution studies and particularly for bioenergy research given the significant distance‐based restrictions on the viability of bioenergy crops. Maps representing the spatial variation of energy demand for the year 2009 were created using publicly available sub‐national gas and electricity consumption data. A new statistical model based on census data was used to increase the spatial resolution. The energy demand was split into thermal energy (the heat energy required for space heating and hot water) and electricity used for purposes other than heating (nonheating electricity or NHE) and was determined separately for the domestic and nondomestic sectors. ‘Scenario factors,’ representing the fractional change at national level in the demand for heat and NHE, were derived from scenarios constructed by UKERC. These scenarios represent a range of pathways from the present day to 2050. The present work focused on the two cases of greatest relevance, the ‘low carbon’ and ‘additional policies’ scenarios, and factors for both were derived, for the demand types described, for every 5 years between 2000 and 2050. Approximately, future spatial energy demands can be obtained by applying the scenario factors to the base mapping data for 2009.

Impact of occupant behaviour on the energy-saving potential of retrofit measures for a public building in the UK

ABSTRACT In building refurbishment projects, dynamic building simulation is popularly used to predict the energy-saving potential of various refurbishment scenarios. However, in this process, it is not clear whether occupant behaviour should be carefully modelled due to the lack of evidence about its impact on the prediction results. To answer this question, this study selected a UK public building and used dynamic building simulation to predict the energy-saving potential of common refurbishment measures, under various occupant behavioural conditions. The results revealed that for the case study building occupants’ heating behaviour has a significant impact on the predicted energy-saving potential of all evaluated refurbishment measures: when changing from passive heating users to active heating users, the energy-saving potential was nearly doubled. Although occupants’ window opening behaviour was not shown to be as important as heating behaviour for the refurbishment of the case study building, it has a specific influence on the refurbishment measure of increasing window layers: when windows are opened longer, the effectiveness of increasing window layers on promoting the building energy efficiency is decreased. According to the findings from this study, occupant behaviour should be considered as an important aspect in building refurbishment projects.

Establishing the zero-carbon performance of compact urban dwellings

This paper presents an analysis of the zero-carbon performance of a case-study building which is representative of a growing number of new buildings that are being built on redevelopment sites in inner-city areas in the UK. Compact urban dwellings are apartment style buildings with a floor area of ∼50 m2 per dwelling, often based over two floors. The constraints of this type of building on achieving zero-carbon performance in the context of the Code for Sustainable Homes is discussed and the shortcomings of the code are demonstrated in terms of the target heat and electricity demand targets for the design of the building systems. A graphical representation of the simulation results is used to present the findings. It has been demonstrated that in specific urban contexts, zero-carbon performance as defined within the current UK compliance framework may be very difficult to achieve in practice given the assumptions used in the simulation here. Therefore, it is very likely that zero-carbon compact urban dwellings may require a net off-site import of electrical and/or thermal energy.

Occupant behaviour modelling in domestic buildings: the case of household electrical appliances

This paper presents a new approach to bottom-up stochastic occupant behaviour modelling for predicting the use of household electrical appliances in domestic buildings. Three metrics relating to appliance occupant behaviours are defined: the number of switch-on events per day, the switch-on times and the duration of each appliance usage. The metrics were calculated for 1,076 appliances in 225 households from the UK Government’s Household Electricity Survey carried out in 2010–2011. The analysis shows that occupant behaviour varies substantially between households, across appliance types and over time. The new modelling approach improves on previous approaches by using a three-step process where the three-appliance occupant-behaviour metrics are simulated respectively using stochastic processes to capture daily variations in appliance occupant behaviour. It uses probability and cumulative density functions based on individual households and appliances which are shown to have advantages for modelling the variations in appliance occupant behaviours.

Control of Carbon Dioxide Concentration in Educational Spaces Using Natural Ventilation

Abstract This paper reports on research carried out to develop natural ventilation control strategies for densely occupied learning spaces with the intention of improving indoor air quality and heating energy consumption. Investigations were carried out for two test cases according to the characteristics given in CIBSE Guide A (2006) and Building Bulletin (BB) 101 (UK Department for Education, 2006). The performance of these test cases were assessed using dynamic thermal simulation with fixed CO2set-points, based on which opening dampers are controlled. Improvements to the control strategy are then proposed. The results show that acceptable indoor air quality can be achieved in almost all cases by adopting typical, traditional control strategies. However, energy consumption can be reduced further by applying more advanced control strategies which use two CO2set-points to regulate the opening sizes in a non-linear, but stepwise manner. Simulation results predict savings in heating energy consumption of at least 30%.

Spatial mapping of Great Britain's bioenergy to 2050

In this Special Issue, we present a series of papers arising from two related research projects funded by the UK Energy Research Centre (UKERC), ‘Spatial Mapping and Evaluation of Energy Crop Distribution in Great Britain (GB) to 2050’ and ‘The Disaggregated Scenarios for Demand Studies (DS4DS) project’, conducted by a team from the University of Aberdeen, University of East Anglia, Forest Research, University of Southampton, Centre for Ecology and Hydrology, Scotland’s Rural College, University of Portsmouth and Loughborough University. Despite considerable interest in second generation, nonfood bioenergy crops, such as the giant grass Miscanthus, and short rotation coppice (SRC) species like willow or poplar, to date no attempt has been made to match potential supply with demand. In this project, we have attempted to do this. Currently, energy crops are cofired with fuels like coal in traditional power stations, but the most carbonand cost-efficient way to use biomass energy is to generate heat and power at the same time through Combined Heat and Power (CHP) plants. To make the best use of bioenergy crops, a future infrastructure of small and mediumsized CHP plants using locally sourced biomass would be required. To see where heat and electricity are most needed, and where bioenergy crops are best grown to meet that demand, the papers collected in this special issue describe how the team have generated high resolution (1 km) maps of demand, potential bioenergy supply, and the size and location of the CHP plants that would be required to exploit the resource for energy. The final papers then examine the economics of using bioenergy to supply heat and electricity – i.e. whether it makes sense from an energy price and from a grower’s perspective, and consider the cost of greenhouse gas abatement provided by bioenergy. The first paper (Lovett et al., 2014) examines the land available to grow bioenergy crops. Not all areas are suitable for energy crop production; for example protected areas and peatlands will be unsuitable, and these areas are mapped at high resolution. By applying different constraints, the available area for energy crops is found to be between 8.5 and 9 M ha (37–40% of GB), and the location of current energy crops is compared to these available areas. In Hastings et al. (2014), state-of-the-art, processbased models of Miscanthus, SRC and short rotation forestry are used to simulate potential yield under current conditions, and under future climate (to 2050). These models identify which crop produces the most biomass on land suitable for bioenergy crops. This paper defined the potential supply of biomass at high resolution (1 km) now and in the future, and shows significant technical biomass potential in GB. Having defined potential biomass supply, Taylor et al. (2014), used detailed energy and census statistics to map demand for heat and electricity at 1 km resolution for Great Britain, both now and, using UKERC scenarios, to project these demand surfaces out to 2050. These high resolution demand estimates are the first of their kind in GB, and provide the first opportunity to make a detailed comparison between supply and demand. With high resolution datasets of potential supply of biomass feedstock and electricity and heat demand, an economic optimization model is used in Wang et al. (2014) to determine how much demand could be met by the available supply at competitive energy prices, and where and what size the CHP plant would be needed to make use of the bioenergy efficiently. The optimization model was used by Wang et al. (2014) to map optimal supply and demand for GB now and to 2050 from an energy price perspective. In Alexander et al. (2014a), a farm-scale economic model is used to examine the farm level optimization problem, that is, at what price farmers might consider growing energy crops, taking account of the costs and returns associated with competing crops. In this paper, maps of bioenergy crops that match supply and demand are derived, avoiding unsuitable areas, and that make economic sense from an energy price and a grower’s perspective. The areas for future growth of bioenergy crops are different to where they are currently grown because energy crops are currently grown to cofire in large conventional power plants, rather than in smaller CHP plants, which would be a more appropriate infrastructure for bioenergy use in the future.

ICT-enabled energy efficiency – a lens onto practices of other sectors

Purpose – The potential and opportunity offered by Information and Communication Technologies (ICTs) to enable Energy Efficient (EE) viable operations has been thoroughly laboured with respect to sustainability goals. Often the issue is not a lack of technological options, but rather an issue in understanding what choices will lead to the greatest impact. This paper summarises the outcome of a research work undertaken within Roadmap Enabling Vision and Strategy for ICT-enabled EE (REViSITE), an EU-funded project tasked with investigating migration pathways from current state of the art to a common vision for ICT-enabled EE with respect to four energy intensive sectors (energy grids, built environment, manufacturing and lighting). In this paper the focus is particularly on the built environment and how it might benefit from other sectors. Design/methodology/approach – The REViSITE methodology/framework combined Life Cycle thinking, an adapted capability Maturity Framework and the REViSITE-developed SMARTT ...

UK photovoltaic field trials—observations on buildability

SYNOPSIS Recent interest in UK building-integrated photovoltaic systems has developed a need for the documentation and assessment of UK photovoltaic (PV) projects. The performance and reliability of PV systems is generally well understood. However, as more architects, building developers and planners become involved in PV projects, there is a need for greater understanding of the whole process of PV installation. This paper addresses this need, with a study of the Heron Close Project in the UK Photovoltaic Domestic Field Trial. This is an installation of thirty PV systems onto residential housing. The design and installation of the PV systems, and the constraints on these processes, are described. An assessment of the “buildability” of the PV systems, in terms of architectural integration and the installation procedures, is presented. The initial performance of the systems and the problems encountered are also discussed.