Energy use in non-domestic buildings: the UK government's new evidence base

Policy for reducing carbon emissions from non-domestic buildings in the UK relies at present on survey and modelling work carried out in the 1990s. The UK government's Department of Energy and Climate Change (DECC) is engaged in a programme of new research to update this evidence base. The work has two main components. The first is a database – the National Energy Efficiency Data framework (NEED) – in which floor area and activity data for non-domestic premises are being linked to electricity and gas consumption at the individual property level. The second is a research project of sample surveys designed to elicit information about buildings and energy use, but also opportunities for abatement and the behavioural and organizational factors affecting efficiency improvements. A pilot survey of the food and mixed retail sector has been carried out in advance of further surveys of the entire range of building types. The research programme is described along with some of the methodological problems it raises.     

Modelling a whole building stock: domestic,non-domestic and mixed use

ABSTRACT

Work on energy use in buildings – in university research, professional practice and government – has tended to draw a broad distinction between ‘the domestic stock’ and ‘the non-domestic stock’. A further tendency has been to focus attention on types of non-domestic buildings devoted to single uses (e.g. offices, shops or hospitals). This paper reports an empirical research programme in which the complete building stock in large areas of England and Wales is comprehensively represented in great detail, using a new method and model called 3DStock. The model breaks down activities by floor level and within each floor of every building. The results show that the extent of mixing of uses is much greater than has previously been acknowledged, especially towards the centres and in the older parts of towns and cities. These mixed-activity buildings are sometimes relatively simple combinations of domestic and non-domestic, e.g. urban retail with flats above, while others are complex mixtures of different non-domestic activities. The model can be used to investigate how these complex relationships influence energy use. It is argued that, at the larger scale, explicit account needs to be taken of the mixing of uses in future stock models for research and policy-making.     

The effect of appliance energy efficiency improvements on domestic electric loads in European households

Across Europe domestic electricity consumption is on the rise. In an attempt to counter this increase, various initiatives have been introduced to promote the replacement of less energy-efficient appliances with more efficient ones. Whilst the likely aggregate effect of such measures over long time periods has been modelled extensively, little is known about the affect that a change to higher efficiency appliances will have on the electrical demand profile of individual households at higher temporal resolutions. To address this issue a means by which established approaches to detailed electrical demand modelling can be adapted to simulate the improvements in the efficiency of appliances is elaborated in this paper. A process is developed by which low-resolution empirical appliance demand data can be transformed to produce high-resolution electrical demand data for different periods in the year, factoring in improvements in appliance performance. The process is applied to simulate the effects a changeover to more energy-efficient appliances would have on the minute resolution demand profiles of a group of households. Results indicate that improving the energy-efficiency of appliances in households leads to a significant reduction in electrical energy requirements but does not appear to have a significant affect on the peak electrical demand.     

基于规范型建筑能耗模型对某建筑的节能分析

规范型建筑能耗模型是一种基于国际能耗规范对建筑能耗现状进行评价、分析的方法。相比于详细建筑模型软件(如Energy Plus),规范型建筑能耗模型具有建模快、速度快等优势。基于规范型建筑能耗模型,对中国石油大学(华东)某办公楼的能耗现状进行分析,并对节能方案进行评估。结果表明,规范型建筑能耗模型对于我国办公楼的能耗分析具有较好的应用前景。     

Energy and urban built form: an empirical and statistical approach

The geometrical forms of buildings have important effects on their use of energy. These relationships are explored at the scale of the entire non-domestic building stock of London. A three-dimensional digital model of the city is used to make a series of geometrical measures: building volume, exposed surface area (walls plus roof) and plan depth. These are compared with figures for the consumption of gas and electricity published by the UK Department of Energy and Climate Change (DECC). The comparisons are made at different levels of spatial aggregation, from boroughs to census districts. Strong correlations are demonstrated between exposed surface area and both gas and electricity use. The analysis also provides some evidence of a sharp increase in electricity use in districts with buildings whose depth in plan exceeds 14 m (in which air-conditioning and permanent artificial lighting are typically required). A multiple regression model is used to measure the contribution of these effects to total energy use, as compared with floor area, activities and number of employees.     

Eawag Forum Chriesbach—Simulation and measurement of energy performance and comfort in a sustainable office building

The Eawag's new headquarters “Forum Chriesbach” is an exemplary illustration of a ‘sustainable’ construction design for office buildings. With a unique combination of architectural and technical elements the building reaches a very low 88 kWh/m² overall primary energy consumption, which is significantly lower than the Swiss Passive House standard, Minergie-P. A monitoring and evaluation project shows that the building is heated mainly by using the sun and internal heat gains from lighting, electrical appliances and occupants, resulting in an extremely low space heating demand. Cooling is provided by natural night time ventilation and the earth-coupled air intake, which pre-cools supply air and provides free cooling for computer servers. However, values for embodied energy and electricity consumption remain significant, even with partial on-site electricity production using photovoltaics. TRNSYS computer simulations show the contributions of individual building services to the overall energy balance and indicate that the building is resilient towards changes in parameters such as climate or occupancy density. Measurements confirm comfortable room temperatures below 26 °C, even during an extremely hot summer period, and 20-23 °C in the winter season. An economic analysis reveals additional costs of only 5% compared to a conventionally constructed building and a payback-time of 13 years.     

Understanding the New Zealand non-domestic building stock

Unlike the residential building stock, most countries have poor information on their non-domestic stock. This necessitates the use of other data sources. In the mid-1980s the (then) New Zealand Department of Valuation digitized its valuation records. This permitted the first analysis of an entire country's non-domestic buildings. A very long-tail probability density function was identified, with the largest 5% of buildings containing more than 40% of the floor space. This knowledge informed the development of research for understanding non-domestic buildings as well as underpinning the 1996 revision of the NZ Building Code Clause H1 Energy Efficiency. More recently an analysis of valuation data has provided the Building Energy End-use Study (BEES) with a national sampling frame to examine energy and water end-uses in non-domestic buildings. The development of processes for collecting and analyzing data is described. Considerable changes in understanding of valuation data have occurred for documenting the non-domestic building stock. New online and geographic information sources can validate and improve building data. The use of such a database supports improved understanding of the changing nature of the building stock and potential intervention points, as well as harnessing regulatory and market forces.     

Enabling urban-scale energy modelling: a new spatial approach

Urban-scale energy modelling provides an ideal tool for studying non-domestic energy consumption and emissions reduction at the community level. In principle, an approach based on the characteristics of individual commercial premises and buildings is attractive, but it poses a number of challenges, the most immediate of which is deciding precisely what to model. For a range of reasons connected with their self-contained nature, individual non-domestic buildings would ideally be selected. However, the main information sources available – digital mapping and business taxation data – are not based on ‘buildings’ and do not use the concept, thus making an automated approach problematic. At the same time, manual identification of the distinct buildings in a city is not a practical proposition because of the numbers involved. The digital mapping and business taxation data are brought together in the Local Land and Property Gazetteer (LLPG). An analysis of the relationships between the relevant elements, namely building polygons and premises attracting business taxation, allowed a unit to be defined that matches the definition of a ‘building’ in most circumstances and can be applied without the need for human intervention. This novel approach provides a firmer basis for modelling non-domestic building energy at the urban scale.     

Simulating space heating demand with respect to non-constant heat gains from household electricity

It is crucial to perform energy simulations during the building process to design a building that meets requirements regarding low energy use. In a low energy building, internal heat gains such as excess heat from household electricity are a large part of the heat balance of the building. The internal heat gains depend on the occupants and are not constant, although they are often assumed constant in simulations of space heating demand. This article analyses how different usage patterns of household electricity affects simulated space heating demand. Parametric studies of energy use-related parameters were done to study the influence from different designs. The results show that the different energy use patterns affect the space heating demand, especially in low energy buildings and during the colder parts of the year. To make accurate energy simulations of low energy buildings, household electricity use patterns should be taken into account.     

Domestic electricity use: A high-resolution energy demand model

The pattern of electricity use in an individual domestic dwelling is highly dependent upon the activities of the occupants and their associated use of electrical appliances. This paper presents a high-resolution model of domestic electricity use that is based upon a combination of patterns of active occupancy (i.e. when people are at home and awake), and daily activity profiles that characterise how people spend their time performing certain activities. One-min resolution synthetic electricity demand data is created through the simulation of appliance use; the model covers all major appliances commonly found in the domestic environment. In order to validate the model, electricity demand was recorded over the period of a year within 22 dwellings in the East Midlands, UK. A thorough quantitative comparison is made between the synthetic and measured data sets, showing them to have similar statistical characteristics. A freely downloadable example of the model is made available and may be configured to the particular requirements of users or incorporated into other models.     

Performance of a reversible heat pump/organic Rankine cycle unit coupled with a passive house to get a positive energy building

This paper presents an innovative technology that can be used to deliver more renewable electricity production than the total electrical consumption of a building while covering the heat demand on a yearly basis. The technology concept uses a heat pump (HP), slightly modified to revert its cycle and generate electricity, coupled to a solar thermal collector roof. This reversible HP/organic Rankine cycle unit presents three operating modes: direct heating, HP and organic Rankine cycle. This work focuses on describing the dynamic model of the multi-component system followed by a techno-economic analysis of the system under different operational conditions. Sensitivity studies include: building envelope, climate, appliances, lighting and heat demand profiles. It is concluded that the HP/ORC unit can turn a single-family house into a PEB under certain weather conditions (electrical production of 3012?kWh/year and total electrical consumption of 2318?kWh/year) with a 138.8?m² solar roof in Denmark.     

Identifying trends in the use of domestic appliances from household electricity consumption measurements

Results are presented from a monitoring study of the electricity consumption of a sample of UK domestic buildings. Five-minutely average whole house power consumption was recorded for 72 dwellings at five sites over a 2-year monitoring period. The mean annual electricity consumption for the households increased significantly by 4.5% (t = 1.9; p < 0.05, one-tailed) from the first to the second year of monitoring. New techniques are developed which estimate the electricity consumption of different appliance groups, based on analysis of the five-minutely monitored data. The overall increase in electricity consumption is attributed to a 10.2% increase in the consumption of ‘standby’ appliances (such as televisions and consumer electronics) and a 4.7% increase in the consumption of ‘active’ appliance (such as lighting, kettles and electric showers). The consumption of different energy user groups (low, medium and high) is also investigated and low and high users are identified as contributing to the overall increase in consumption. The need for further investigation, such as quantitative and qualitative studies, to improve understanding in domestic electricity consumption is discussed.     

Modelling electricity consumption in office buildings: An agent based approach

In this paper, we develop an agent-based model which integrates four important elements, i.e. organisational energy management policies/regulations, energy management technologies, electric appliances and equipment, and human behaviour, to simulate the electricity consumption in office buildings. Based on a case study, we use this model to test the effectiveness of different electricity management strategies, and solve practical office electricity consumption problems. This paper theoretically contributes to an integration of the four elements involved in the complex organisational issue of office electricity consumption, and practically contributes to an application of an agent-based approach for office building electricity consumption study.     

Development of envelope efficiency labels for commercial buildings: Effect of different variables on electricity consumption

After the first federal law on energy efficiency was published in 2001, the Brazilian government promoted several actions on energy efficiency, including the Federal Regulation for Voluntary Labeling of Energy Efficiency Levels in Commercial, Public and Service Buildings. Divided into three parts, lighting system, HVAC and building envelope, it is expected to become mandatory in 2013. This paper describes the criteria adopted to evaluate the envelope efficiency level, focusing on the development of a regression equation which provides an electricity consumption indicator. The envelope label is divided into five efficiency levels, from A (more efficient) to E (less efficient), identified according to the electricity consumption indicator. The linear regression equation considers variables such as window to wall ratio (WWR), SHGC, solar protection angles, building volume indicators and the roof U_value. The U_value of the walls was excluded from the equation due to its non-linearity. Its relation with electricity consumption depends on internal gains, exterior temperatures, building size and thermal capacity of the walls and could not be described by a linear regression equation. Some limitations were identified and shape factor limits were provided. The envelope efficiency label is obtained by the comparison of the electricity consumption indicator of the proposed building with the electricity consumption indicators of two other building envelopes presented.     

重庆城市发展新区村镇住宅建筑用能模型

通过对重庆市城市发展新区村镇住宅建筑能耗的全年调研,得到了重庆城市发展新区村镇居民的用能习惯及村镇建筑的能耗水平。采用分类归纳法,对家用电器测试归纳,并对非用电设施调研估算归纳。基于实测数据和调研估算数据建立了重庆城市发展新区村镇住宅建筑用能模型,并进行验证。结果表明,重庆城市发展新区村镇住宅能源消费形式以电为主,为电＋燃气＋薪柴＋煤＋太阳能的混合型结构;村镇居民用能习惯在使用何种能源的选择上存在差异,但对同一种能源的使用差异性不大。实测数据表明,所建立的村镇住宅建筑用能模型能准确反映重庆城市发展新区新村镇住宅建筑用能的实际情况。     

基于粗糙集的夏热冬暖地区建筑能耗关键指标识别研究

对建筑能耗关键指标识别是建筑节能的基础,是进行建筑能耗预测和正确决策的前提。采用文献研究法、专家调查法对住宅建筑能耗指标进行分类,即能源种类指标、能源驱动因素指标、能源用途(能源消耗终端种类)指标。基于粗糙集理论,采用Johnson算法,利用Rosetta软件对建筑能耗关键指标进行识别。结果显示,煤、电、石油液化气、可再生能源是目前建筑能耗中主要的4种能源。人均GDP、人口总量、建筑面积是建筑能耗的主要驱动因素,家用电器、空调、炊事、照明是建筑能耗的主要因素。     

Evaluation of environmental design strategies for university buildings

ABSTRACT

This paper examines the performance of environmental strategies in seven recently constructed or refurbished university buildings in the UK. These buildings contain a range of administrative spaces, classrooms, libraries and studios, reflecting their often complex, multi-use, heterogeneous nature. The key features of each environmental strategy are described (including passive, mixed-mode or active systems), in the context of the occupants and spaces they serve and the level of interaction that they afford. Energy performance and occupant thermal comfort (assessed by user surveys) are analysed and compared with studies of other non-domestic buildings, which have typically focused on more predictable single administrative uses (e.g. government offices), and unusually effective operation scenarios (e.g. continuous monitoring by expert building managers). The paper concludes by examining two of the case studies that reflect an increasingly common model of ‘flexible’ environmental design in more detail, identifying key features of the strategies for each building that have had a significant impact on their performance. The design assumptions leading to these features will be explored, and key lessons identified, contributing towards the development of a more robust evidential basis for choosing appropriate environmental strategies for university and other non-domestic buildings in the UK.     

Using dynamic simulation to quantify the effect of carbon-saving measures for a UK supermarket

A standard UK supermarket design is used to simulate the energy performance, and subsequent CO₂ emissions, of a modern-day UK supermarket building. Retrofit measures are proposed to reduce these CO₂ emissions by over 50%, mostly due to demand-side measures but also accounting for likely onsite supply-side solutions. The influence of refrigeration and lighting in such buildings is explored and the possible use of heat recovery systems discussed. The air-tightness of supermarket buildings is also highlighted as a potential area for significant energy savings. Finally, the reliance on grid electricity is demonstrated for non-domestic buildings with a high electrical energy use. A combined approach of energy efficiency and low-carbon offsite electrical generation is suggested from the described case study as the most successful strategy to achieve large carbon savings (i.e. >50%) in existing supermarket buildings.     

Material stocks in Germany's non-domestic buildings: a new quantification method

The building sector consumes large quantities of resources and generates high levels of construction and demolition (C&D) waste. From an ‘urban mining’ perspective, the building stock can be seen as a repository of natural resources. In order to manage this repository, evidence is needed on its quantity and dynamics. Although data exist for domestic buildings, little evidence exists for non-domestic buildings. A new method is presented to quantify the material stock of non-domestic buildings – based on the German building stock. The quantification process involves three steps: (1) material composition indicators (MCIs) are calculated with respect to various building types; (2) the country's total floor space is estimated and disaggregated; and (3) the total material stock is calculated. The main results are MCIs and the floor space for both domestic and non-domestic stocks, as well as the material mass in total. In Germany the total material mass of non-domestic buildings is approximately 6.8 billion tonnes, accounting for 44% of the entire building stock. The method can be adapted and validated for use in other countries. These results will assist both policy-makers and the construction industry to understand the potential for moving toward a more circular economy.     

建筑物能源审计研究--香港铜锣湾综合商业大楼的能源审计实例

以该商业大楼为例,详细介绍了建筑物能源审计的研究结果。该楼宇设备的复杂多样性,为能源审计提供了完整的能耗数据,使得能源审计工作得以深入进行。在能源审计中应用了问卷调查、现场实测和能源收费账单统计等手段,收集了公共设备和租户空调设备、照明负荷、办公设备负荷等的能源消耗情况。确定了建筑物整体能耗水平,并将此结果与香港地区典型建筑的能耗水平相比较。根据研究结果,提出了有针对性的节能措施。