Climatic and internal factors affecting future UK office heating and cooling energy consumptions

There is a large consensus concerning the expected trend, if not the magnitude of change, of the UK climate in the coming decades [Climate Change 2007: Impacts, Adaptation and Vulnerability, Intergovernmental Panel on Climate Change, April 2007]. This study aims to quantify how such changes will have a direct effect on heating and cooling energy use in future office environments (i.e. by the year 2030). When considering future offices, it is also necessary to account for a change in the small power and lighting equipment being used, in this case by assuming an improved efficiency in both categories. This will also have a significant effect on the balance of heating and cooling an office. Furthermore, the subtle effect of a change in location within the UK can affect results further, with northern cities having substantially higher heating loads (and lower cooling loads) than southern locations. Such factors can influence approaches towards reducing future office energy demands and, in some cases, be the difference between a heating-dominated or cooling-dominated building. This study should also inform future choices for supplying energy to office buildings, in particular microgeneration options. It confirms the importance of dealing with demand-side changes before assessing the supply-side opportunities, with buildings having very different heating and cooling needs post-refurbishment. The study also highlights the importance, and possibilities, of adapting to future climates, and the benefits of promoting heating-dominated buildings instead of cooling-dominated.     

The performance of air-source heat pumps in current and future offices

A typical UK office is used as an exemplar for office energy use in the UK. The effect of replacing existing boilers and air-conditioning systems with air-source heat pumps (ASHPs) is investigated for a “current” version of the office, with typical equipment/lighting usage, fabric and internal gains, and also for a “2030” office, where fabric is improved, equipment/lighting made more efficient and, as a result, internal gains reduced. The ASHPs, as a potential carbon-saving technology, performs slightly differently for the two office scenarios. Furthermore, after removing the boiler, it is found to be important whether electric hot water or gas hot water point-of-use heaters are adopted with the ASHPs (assuming that the existing boiler would not be used if the ASHPs is satisfying all space heating requirements). This can be the difference between ASHPs reducing and increasing the carbon emissions of the office. Finally, the carbon intensity of the grid has a large effect on the success of ASHPs technology. This is quantified through a sensitivity analysis, indicating the external conditions for which ASHPs might reduce CO₂ emissions for office buildings. The results suggest that an ASHPs has the potential to reduce CO₂ emissions for certain conditions, but should not be seen as a guaranteed low-carbon technology for all scenarios. As well as assessing the ASHPs as a carbon-saving technology, potential economic benefits are also estimated based on running costs and predicted reduction in energy bills.     

A future bamboo-structure residential building prototype in China: Life cycle assessment of energy use and carbon emission

In this study, the material-based energy use and carbon emission over the life cycle of a bamboo-structure residential building prototype with innovative insulation technologies are analyzed. In comparison with a typical brick-concrete building, the bamboo-structure building requires less energy and emits less carbon dioxide to meet the identical functional requirements, i.e., envelope insulation and structure supporting. In order to systematically assess the energy use and carbon emission, several scenarios are designed based on the LEED standard and the technical potentials. The results indicate that there is a potential to reduce 11.0% (18.5%) of the embodied energy (carbon) for the use of recycled-content building materials and 51.3% (69.2%) for the recycling of construction and demolition waste, respectively. However, the practical effect of the potentials varies significantly depending on project management levels and available technologies in the current market. The analysis provides an insight into the assessment of the material-based energy use and carbon emission over the life cycle of a building.     

Energy impact assessment for the reduction of carbon dioxide and formaldehyde exposure risk in air-conditioned offices

Treatment of fresh air in ventilation systems for air-conditioning consumes a considerable amount of energy and affects the indoor air quality (IAQ). In this study, energy impact on ventilation systems was examined against certain IAQ objectives for indoor formaldehyde exposure risk in air-conditioned offices of Hong Kong. Thermal energy consumptions for ventilation systems and indoor formaldehyde exposure concentrations based on some regional surveys of typical offices in Hong Kong were reviewed. The thermal energy consumptions of ventilation systems operating for CO₂ exposure concentrations between 800 ppmv and 1200 ppmv for typical office buildings and the corresponding formaldehyde exposure risks were evaluated. The results showed that, for a reference indoor environment at a CO₂ exposure concentration of 1000 ppmv, the average thermal energy saving of ventilation system for a unit increment of the acceptable formaldehyde exposure limit of 1 h (loss of life expectancy of 0.0417 day) was 280 MJ m⁻² yr⁻¹; and for a unit decrement of the exposure limit of 1 h, an additional average thermal energy consumption of 480 MJ m⁻² yr⁻¹ was expected. This study would be a useful source of reference in evaluation of the energy performance of ventilation strategies in air-conditioned offices at a quantified exposure risk of formaldehyde.     

Evaluating greenhouse gas emission reductions in a synthetic fibre industrial plant with a PET-recycling processing unit

ABSTRACT

This paper reports a greenhouse gas inventory of a synthetic fibre industrial plant from 2008 to 2014. Using long-term inventory data, a mathematical model was designed to forecast tCO₂e emission on a monthly basis, which is important for the company’s business with others that set emission targets for suppliers. Based on the inventory results, statistical analyses were carried out to evaluate the effectiveness of greenhouse gas emission reductions resulting from boiler fuel changes. The inventory methodology follows the Clean Development Mechanism. Indirect emission reductions are calculated. These are not considered in the methodology. The viability of the company’s entering the voluntary carbon credit market is calculated on the basis of successful emission reductions.     

Carbon print studies for the energy conservation regulations of the UK and China

The recently published building energy conservation regulation of China (GB50189-2005, 2005 [1]) was compared with the latest UK building energy conservation regulation (Part L) (Building Regulation Approved Document L2A, 2006 [2]). The UK regulation appeared stricter in its requirements and standards than the Chinese regulation. In two case studies, the design of a sample building is altered to fulfil the minimum requirements of the two regulations. The energy consumption and Carbon print of the virtual building under the two set of regulations are estimated by computer based models in the two case studies based on a building in the Cold regions. The building under the UK regulation showed higher energy efficiency and less Carbon emissions per year. The high level estimate in the case studies discovered a potential energy savings of 29% by strengthening the design requirements in the Chinese regulation to the UK level. The improvement on energy efficiency of buildings can be achieved in strengthening the proactive design aspects on building envelope, efficient HVAC, lighting and lighting control system. The software used was SBEM which is the default tool in the UK Part L regulation.     

The reality and future scenarios of commercial building energy consumption in China

While China's 11th Five-Year Plan called for a reduction of energy intensity by 2010, whether and how the energy consumption trend can be changed in a short time has been hotly debated. This research intends to evaluate the impact of a variety of scenarios of gross domestic product (GDP) growth, energy elasticity and energy-efficiency improvement on energy consumption in commercial buildings in China using a detailed China End-Use Energy Model.China's official energy statistics have limited information on energy demand by end-use. This is a particularly pertinent issue for building energy consumption. The authors have applied reasoned judgments, based on experience of working on Chinese efficiency standards and energy-related programs, to present a realistic interpretation of the current energy data. The bottom-up approach allows detailed consideration of end-use intensity, equipment efficiency, etc., thus facilitating assessment of potential impacts of specific policy and technology changes on building energy use.The results suggest that: (1) commercial energy consumption in China's current statistics is underestimated by about 44%, and the fuel mix is misleading; (2) energy-efficiency improvements will not be sufficient to offset the strong increase in end-use penetration and intensity in commercial buildings; (3) energy intensity (particularly electricity) in commercial buildings will increase; (4) different GDP growth and elasticity scenarios could lead to a wide range of floor area growth trajectories, and therefore, significantly impact energy consumption in commercial buildings.     

HVAC system strategies for energy conservation in commercial buildings in Saudi Arabia

In recent years, there has been a dramatic increase in energy consumption in Saudi Arabia. The building sector being the largest consumer of electric energy represents a major potential contributor for reducing energy consumption. Due to their functional and operational characteristics, commercial buildings relatively consume more energy (per unit area) than other types of buildings. The heating, ventilating and air-conditioning system (HVAC) is one of the largest end-users of energy in these buildings, particularly in harsh climates. Energy efficient design and operation of HVAC systems in commercial buildings can offer major opportunities for reduced energy consumption and contribute to sustainable development. However, improper utilization of energy conservation measures can result in reduced environmental quality. This in turn exposes the occupants to thermal discomfort and health risks, and consequently diminishes the economic value of the facility. Therefore, a well assessed and balanced energy conservation strategy is required to achieve energy efficiency while maintaining desired level of thermal comfort. In this study, major design and operational parameters for different types of HVAC systems influencing energy consumption are investigated utilizing the Visual-DOE program. Results indicate that energy savings of up to 30% can be obtained while maintaining acceptable level of thermal comfort when HVAC systems are properly selected and operated.     

The limited role for Carbon Capture and Storage (CCS) technologies in a sustainable Australian energy future

There is considerable debate regarding the potential role of Carbon Capture and Storage (CCS) technologies in reducing Australia's greenhouse emissions. The latest climate change science suggests that major (60% or more by 2050), rapid (peaking within 20 years) cuts in global emissions may be required to avoid dangerous climate change. There are a number of existing abatement options including energy efficiency, various renewable energy technologies, nuclear power and fuel switching to natural gas; as well as emerging options including CCS. We outline a simple technology assessment framework for policymakers to evaluate these different options given the climate change imperative. This framework includes technology status, delivered energy services, present and possible future costs, potential scale of abatement, potential speed of deployment and other possible social outcomes. Application of this framework to CCS suggests that it should be considered as a promising, but still somewhat unproven, option that potentially offers very significant abatement potential and good integration into the existing energy industry. There are, however, some outstanding questions regarding its effectiveness and safety, its abatement is likely to come at significant cost, and it is unlikely to be able to make a significant contribution for well over a decade. The Australian policy implications are that while government support for R&D and Demonstration of CCS is appropriate and should in our view be expanded, the major priority should be to support greater deployment of existing abatement options including energy efficiency, efficient gas-fired generation and cogeneration and renewable energy. Such policy support is noticeably lacking at present.     

Effects of energy and carbon taxes on building material competitiveness

The relations between building material competitiveness and economic instruments for mitigating climate change are explored in this bottom-up study. The effects of carbon and energy taxes on building material manufacturing cost and total building construction cost are modelled, analysing individual materials as well as comparing a wood-framed building to a reinforced concrete-framed building. The energy balances of producing construction materials made of wood, concrete, steel, and gypsum are described and quantified. For wood lumber, more usable energy is available as biomass residues than is consumed in the processing steps. The quantities of biofuels made available during the production of wood materials are calculated, and the cost differences between using these biofuels and using fossil fuels are shown under various tax regimes. The results indicate that higher energy and carbon taxation rates increase the economic competitiveness of wood construction materials. This is due to both the lower energy cost for material manufacture, and the increased economic value of biomass by-products used to replace fossil fuel.     

Reduction of greenhouse gas emissions from UK hotels in 2030

The feasibility of halving greenhouse gas emissions from hotels by 2030 has been studied as part of the Carbon Vision Buildings Programme. The aim of that programme was to study ways of reducing emissions from the existing stock because it will be responsible for the majority of building emissions over the next few decades. The work was carried out using detailed computer simulation using the ESP-r tool. Two hotels were studied, one older and converted and the other newer and purpose-built, with the aim of representing the most common UK hotel types.     

The future of nuclear power in Europe: a response

Two interlinked and complex problems face energy policy‐makers: future energy supplies and climate change. The choices made on energy mix will lock development pathways for some considerable time ahead. Climate change is a challenging problem. Decarbonising the energy system requires sustainable and environmentally friendly technologies that work within the context of the planetary environment and do not cause “collateral damage”. Several approaches are available. But nuclear power is an unsustainable technology that has already caused “collateral damage” and will leave a toxic legacy of waste, for which there appears to be no solution. Including nuclear in a future energy system is a step in the wrong direction.     

Clean-energy policies and electricity sector carbon emissions in the U.S. states

State governments in the United States have enacted various clean-energy policies to decarbonize electric utilities, diversify energy supplies, and stimulate economic development. With a panel data set for 48 continental states from 1990 to 2008, fixed-effect panel regressions are estimated to test the impacts of clean-energy policies on total carbon emissions, electricity consumption, and carbon intensity. The results indicate that supply-side policy tools, such as RPS and EERS, are negatively correlated with carbon intensity in the electricity sector. More aggressive policies are needed to reduce total carbon emissions.     

A review of the impact of climate change on future nitrate concentrations in groundwater of the UK

This paper reviews the potential impacts of climate change on nitrate concentrations in groundwater of the UK using a Source-Pathway-Receptor framework. Changes in temperature, precipitation quantity and distribution, and atmospheric carbon dioxide concentrations will affect the agricultural nitrate source term through changes in both soil processes and agricultural productivity. Non-agricultural source terms, such as urban areas and atmospheric deposition, are also expected to be affected. The implications for the rate of nitrate leaching to groundwater as a result of these changes are not yet fully understood but predictions suggest that leaching rate may increase under future climate scenarios. Climate change will affect the hydrological cycle with changes to recharge, groundwater levels and resources and flow processes. These changes will impact on concentrations of nitrate in abstracted water and other receptors, such as surface water and groundwater-fed wetlands. The implications for nitrate leaching to groundwater as a result of climate changes are not yet well enough understood to be able to make useful predictions without more site-specific data. The few studies which address the whole cycle show likely changes in nitrate leaching ranging from limited increases to a possible doubling of aquifer concentrations by 2100. These changes may be masked by nitrate reductions from improved agricultural practices, but a range of adaption measures need to be identified. Future impact may also be driven by economic responses to climate change.     

Personalized dynamic design of networked lighting for energy-efficiency in open-plan offices

Electric lighting consumes 19% of total electricity production worldwide. Open-plan offices constitute the majority of office stock, in which most office workers perform their daily tasks, and hence the lighting in those offices has significant impact on, not only energy usage, but also occupants’ productivity. This paper presents a unique lighting optimization approach for open-plan offices that is capable of tuning task lighting to each occupant's preference in the most energy-efficient fashion. Exploiting individual controllability of the advanced networked lighting systems, each luminaire can be dynamically actuated at a different level to realize various lighting configurations without any physical rewiring. This research formulates lighting actuation into a linear programming problem and finds the optimal light outputs for each of the luminaires that collaboratively deliver specified lighting to each workstation while using the least amount of energy. Simulations using our lighting optimization approach have shown its versatility in providing proper workstation-specific task lighting under different requirements compared to business-as-usual practices. Energy savings are generated from tuning the light levels to occupants’ needs as well as keeping unoccupied areas unlit or minimally lit with this approach.     

Variability in energy and carbon dioxide balances of wood and concrete building materials

A variety of factors affect the energy and CO₂ balances of building materials over their lifecycle. Previous studies have shown that the use of wood for construction generally results in lower energy use and CO₂ emission than does the use of concrete. To determine the uncertainties of this generality, we studied the changes in energy and CO₂ balances caused by variation of key parameters in the manufacture and use of the materials comprising a wood- and a concrete-framed building. Parameters considered were clinker production efficiency, blending of cement, crushing of aggregate, recycling of steel, lumber drying efficiency, material transportation distance, carbon intensity of fossil fuel, recovery of logging, sawmill, construction and demolition residues for biofuel, and growth and exploitation of surplus forest not needed for wood material production. We found the materials of the wood-framed building had lower energy and CO₂ balances than those of the concrete-framed building in all cases but one. Recovery of demolition and wood processing residues for use in place of fossil fuels contributed most significantly to the lower energy and CO₂ balances of wood-framed building materials. We conclude that the use of wood building material instead of concrete, coupled with greater integration of wood by-products into energy systems, would be an effective means of reducing fossil fuel use and net CO₂ emission to the atmosphere.     

Overcoming barriers to implementation of carbon reduction strategies in large commercial buildings in China

With an economic growth in GDP of around 10% per annum in recent years, energy consumption in the building sector in China now accounts for 25% of the total energy use in the whole nation. In large buildings in Beijing and Shanghai the consumption rate, at approximately 190 kWh/m² per annum, is around five times the energy use in residential buildings in those cities. Addressing this ever increasing energy consumption and the consequential green house gas (GHG) emissions must be a priority to achieve low carbon sustainability in China.     

Adaptive Comfort Degree-Days: A metric to compare adaptive comfort standards and estimate changes in energy consumption for future UK climates

This paper introduces the concept of the Adaptive Comfort Degree-Day, a temperature difference/time composite metric, as a means of comparing energy savings from Adaptive Comfort Model standards by quantifying the extent to which the temperature limits of the thermal comfort zone of the Predicted Mean Vote Model can be broadened. The Adaptive Comfort Degree-Day has been applied to a series of climates projected for different locations (Edinburgh, Manchester and London) under different emissions scenarios in the United Kingdom for the 2020s, 2030s, 2050s and 2080s. The rate at which energy savings can be achieved by the European adaptive standard EN15251 (Category II) was compared with the ASHRAE 55 adaptive standard (80% acceptability) during the cooling season. Results indicate that the wider applicability of the European standard means that it can realise levels of energy savings which its counterpart ASHRAE adaptive standard would not achieve for decades.