Peak load characteristics of Sydney office buildings and policy recommendations for peak load reduction

Growth in peak period electricity demand has driven the requirement for a significant expansion of Sydney's electricity network. Energy efficiency and demand management activities in office buildings may be an alternative to electricity network augmentation, with significant economic and environmental benefits. This paper identifies and characterises trends in electricity peak demand in Sydney's office buildings, comparing a range of high and low energy consuming buildings. The paper assesses the potential for energy efficiency and demand management strategies in office buildings to reduce peak loads and hence defer electricity network augmentation. Base building electricity load data was analysed for a sample of 25 Sydney office buildings, along with Sydney electricity substation and temperature data. Peak loads for buildings with best practice energy performance were found to be 26% lower than for buildings with average energy performance, while annual electricity consumption was 57% lower. With these findings, this paper has assessed the effectiveness of current energy efficiency policy for peak demand management and has recommended strengthening energy efficiency policies in order to capture coincidental peak load reductions, as well as new policies specifically targeting peak demand management. It was found that these measures could offer significant potential to defer network investment.     

Comparison of natural gas driven heat pumps and electrically driven heat pumps with conventional systems for building heating purposes

Electrically driven heat pumps achieve good efficiencies for space heating. If heat pumps are driven directly by a combustion engine instead of an electric motor, losses attributed to the production and transport of electricity are eliminated. Additionally, the use of the combustion engine's heat leads to a reduced temperature difference across the heat pump. This article presents annual efficiencies of these systems and compares internal combustion engine and electrically driven heat pumps in terms of primary energy consumption and CO₂ emissions. Because heat pump performance depends strongly on the heating circuit's flow temperature level, the comparison is performed for air-to-water and geothermal heat pump systems in two cases of maximum flow temperatures (40 °C and 60 °C). These temperature levels represent typical modern buildings with large heating surfaces and older buildings with high-temperature radiators, respectively. In addition to the different heat pump setups, conventional space heating systems are included in the comparison. The calculations show that natural gas-driven heat pumps achieve about the same efficiency and CO₂ emissions as electrically driven heat pumps powered with electricity from the most modern natural gas-fired combined cycle power plants. The efficiency of such systems is about twice that of conventional boiler technologies.     

Life cycle primary energy analysis of residential buildings

The space heating demand of residential buildings can be decreased by improved insulation, reduced air leakage and by heat recovery from ventilation air. However, these measures result in an increased use of materials. As the energy for building operation decreases, the relative importance of the energy used in the production phase increases and influences optimization aimed at minimizing the life cycle energy use. The life cycle primary energy use of buildings also depends on the energy supply systems. In this work we analyse primary energy use and CO₂ emission for the production and operation of conventional and low-energy residential buildings. Different types of energy supply systems are included in the analysis. We show that for a conventional and a low-energy building the primary energy use for production can be up to 45% and 60%, respectively, of the total, depending on the energy supply system, and with larger variations for conventional buildings. The primary energy used and the CO₂ emission resulting from production are lower for wood-framed constructions than for concrete-framed constructions. The primary energy use and the CO₂ emission depend strongly on the energy supply, for both conventional and low-energy buildings. For example, a single-family house from the 1970s heated with biomass-based district heating with cogeneration has 70% lower operational primary energy use than if heated with fuel-based electricity. The specific primary energy use with district heating was 40% lower than that of an electrically heated passive row house.     

The reliability of inverse modelling for the wide scale characterization of the thermal properties of buildings

The reduction of energy use in buildings is a major component of greenhouse gas mitigation policy and requires knowledge of the fabric and the occupant behaviour. Hence there has been a longstanding desire to use automatic means to identify these. Smart metres and the internet-of-things have the potential to do this. This paper describes a study where the ability of inverse modelling to identify building parameters is evaluated for 6 monitored real and 1000 simulated buildings. It was found that low-order models provide good estimates of heat transfer coefficients and internal temperatures if heating, electricity use and CO₂ concentration are measured during the winter period. This implies that the method could be used with a small number of cheap sensors and enable the accurate assessment of buildings’ thermal properties, and therefore the impact of any suggested retrofit. This has the potential to be transformative for the energy efficiency industry.     

Beyond the code: Energy, carbon, and cost savings using conventional technologies

As states in the U.S. adopt new energy codes, it is important to understand the benefits for each state and its building owners. This paper estimates life-cycle energy savings, carbon emission reduction, and cost-effectiveness of conventional energy efficiency measures in new commercial buildings using an integrated design approach. Results are based on 8208 energy simulations for 12 prototypical buildings in 228 cities, with 3 building designs evaluated for each building-location combination. Results are represented by easy-to-understand mappings that allow for regional and state comparisons. The results show that the use of conventional energy efficiency technologies in an integrated design framework can decrease energy use by 15-20% on average in new commercial buildings, and over 35% for some building types and locations. These energy reductions can often be accomplished at negative incremental life-cycle costs and reduce a building's energy-related carbon footprint by 9-33%. However, generalizing these results on energy use, life-cycle costs, and carbon emissions misses exceptions in the results that show the importance of location-specific characteristics. Also, states do not appear to base energy code adoption decisions on either potential energy savings or life-cycle cost savings.     

杭州住宅建筑用电量调查及意义分析

目前,国内绝大多数建筑节能的研究都是基于理论公式或软件热工模拟.由于理论研究和实际情况存在很大差别,最好将理论或模拟的研究结果与实际住宅建筑的用电量相结合.本文首先以杭州市3栋不同时期的住宅楼作为调查研究对象,于2007～2008年进行了为期1年的实际月用电量调查;然后,根据杭州市天气特点,分类并计算出实际采暖制冷用电量;最后,通过对调查结果和相关建筑标准及理论或模拟研究结果进行比较,发现仅仅根据理论公式或热工模拟得出的结果夸大了节能措施或技术的节能效果,不能起到指导建筑节能工作发展的作用,应该采用理论结合实际的方法来研究建筑节能的作用和意义.     

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.     

民用建筑推行用地用电指标的探讨

针对广东省开展的用电指标工作,分析了当前建筑节能工作的瓶颈,论证了控制建筑用电负荷对新建建筑节能的关键作用,结合既有建筑的耗能统计数据和相关标准,给出了用电指标的建议数值。     

Energieeinsparung in Gebäuden ndash; aktueller denn je!: Anforderungskonzept EnEV 2006 ndash; Vision Nachhaltigkeitsvektor

Energy saving in buildings ndash; more updated then ever! Concept of requirements EnEV 2006 ndash; vision vector of sustainability The necessity to conservate energy in the sector of energy consumption in buildings is a result of the aspects such as environment protection, decrease of dependency on import, lowering of second hires, conservation of basic fabric and value, as well as increase of comfort and pump priming of the building industry. Energy saving potentials are well quantifiable for the stock of residential buildings, at non‐residential buildings the state of knowledge is clearly lower. The improvements from the Energy Performance of Buildings Directive (EPBD) compared to the German energy saving ordinance EnEV 2002 contain mainly the consideration of electricity for artificial lighting and cooling energy. Both components virtually do not play any role in residential buildings. Facing the predominant pressure of time ndash; the EPBD has to be converted until 2006 ndash; it seems to make sense to hold the present treatment of residential buildings. For space heating, hot water preparation and ventilation, there exist partly highly differing proportions in non‐residential buildings in contrast to residential buildings; electricity for artificial lighting and cooling energy may become primarily important. For non‐residential buildings, there is a need for development of new calculation methods and a new concept to formalize requirements. The premise of the presented concept is the formulation of usage‐specified requirements. For pragmatic reasons, a “method of reference buildings” is recommended. In addition to the idea of energy saving, for the function of “room conditioning”, a vector of sustainability is proposed. For all rating criterions, objective evaluation factors B are established, which though are supplemented with weighting factors W.     

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.     

Benchmarking electricity consumption

The building stock is one of the largest energy consumers and simultaneously represents a relevant cost driver for most companies. Thus, buildings should be optimally planned, constructed and used from both an environmental and from an economic perspective. Benchmarking electricity consumption in the usage phase is a tool for achieving this objective. This requires a uniform collection of key usage indicators on the one hand, and on the other hand it is necessary to be cognisant of the factors that drive these key indicators and how they do so. This alone makes it possible to satisfy the benchmarking principle of comparing like or similar objects. Uniformly collected key indicators for electricity consumption (kWh/m² usable floor area and year) are presented on the basis of 109 Swiss office buildings. This is broken down into further groupings on the basis of the relevant drivers. The analysis of the drivers relies on regression analysis. This demonstrates above all the great relevance of technical installation (e.g. the share of mechanically vented and ventilated as well as air‐conditioned areas), given that the coverage area of such systems has a significant effect on the electricity consumption of office buildings. Accordingly, special attention should be paid to the planning, construction and use of technical installations, in order to be able to provide optimally energy‐efficient buildings.     

Renewable energy options for buildings: Case studies

This paper deals with a novel approach to study renewable energy options for buildings to make them more efficient, more cost effective, more environmentally benign, and more technologically attractive. To demonstrate the application of this study, four buildings are chosen as case studies with two from the residential sector, one commercial/institutional building, and one industrial building. A ground source heat pump for heating and cooling, a solar water heater for space heating and/or hot water, and a photovoltaic panel to generate electricity are designed for these case studies. Attempt is made to design projects under hybrid systems combined from two technologies are developed for the above-mentioned four cases. Results obtained indicate that solar thermal option for hot water and space heating becomes the most cost effective one for all cases (e.g., $4956 for Cases 1 and 2 and $70,652 for Case 3, and $91,361 for Case 4). In addition, solar electricity through PVs is technologically the most suitable one to meet the electricity demand. The ground source heat pump option is quite attractive from the efficiency and environmental impact point of views although it requires installation and maintenance, etc. Finally, hybrid systems provide better advantages, such as higher efficiency, reduced cost, reduced emissions, etc.     

电供热发展简析

指出电直接供热是能源的低效应用，但可以作为其他供热方式的补充或用于建筑局部供热。认为热泵和电蓄能供热是电供热的发展方向，提出要增强建筑节能和提高供热系统管理水平，倡导冷热电联供和多能源综合利用。     

议居住建筑节能设计标准的差异对节能设计的影响

节能减排是当今社会的重大议题,自2008年10月1日实施《民用建筑节能条例》以来,居住建筑节能设计取得了显著效果,大大降低了居住建筑的能耗,节约了大量能源。但在实际执行过程中,却存在对节能设计概念模糊、节能计算方法有误以及节能设计审查不严等问题。致使出现一些虽形式上满足节能设计要求,但却存在严重能耗问题的伪节能居住建筑。这些问题的存在原因很多,其中各地方节能设计标准本身对节能设计的定义描述、具体要求及评价标准的差异是重要原因之一。论文仅就此方面举例探讨其对节能设计结果的影响,以期对节能设计者提供帮助,给规范修订者提供参考。     

Primary energy implications of end-use energy efficiency measures in district heated buildings

In this study we explore the effects of end-use energy efficiency measures on different district heat production systems with combined heat and power (CHP) plants for base load production and heat-only boilers for peak and medium load productions. We model four minimum cost district heat production systems based on four environmental taxation scenarios, plus a reference district heat system used in Östersund, Sweden. We analyze the primary energy use and the cost of district heat production for each system. We then analyze the primary energy implications of end-use energy efficiency measures applied to a case-study apartment building, taking into account the reduced district heat demand, reduced cogenerated electricity and increased electricity use due to ventilation heat recovery. We find that district heat production cost in optimally-designed production systems is not sensitive to environmental taxation. The primary energy savings of end-use energy efficiency measures depend on the characteristics of the district heat production system and the type of end-use energy efficiency measures. Energy efficiency measures that reduce more of peak load than base load production give higher primary energy savings, because the primary energy efficiency is higher for CHP plants than for boilers. This study shows the importance of analyzing both the demand and supply sides as well as their interaction in order to minimize the primary energy use of district heated buildings.     

The Brazilian energy crisis and a study to support building efficiency legislation

Brazil has gone through an important electricity generation crisis in 2001, but the country does not have as yet a legislation to improve building energy efficiency. The energy efficiency of Brazilian buildings can well be improved, as it was shown during the energy rationing period in 2001. This efficiency increase could usher in gains in quality for indoor environments, as well as lower investments in power generation facilities, including the emission of gases into the atmosphere, flooding arable land for reservoirs, etc. The current work briefly demonstrates the lack of planning that caused the electricity crisis, some results of multi-building studies and simulations of an existing office building of Rio de Janeiro. In this parametric case-study, we have simulated variations of the window–wall ratio (WWR) with different glasses and interior shade, using the natural light, aspects deemed to be of the utmost importance for a future Brazilian building energy efficiency legislation. The need of such legislation has been much increased as a result of the energy generation crisis and its consequences. To take advantage of the problems, in order to improve the quality of the Brazilians buildings, is one of our objectives.     

Primary energy implications of ventilation heat recovery in residential buildings

In this study, we analyze the impact of ventilation heat recovery (VHR) on the operation primary energy use in residential buildings. We calculate the operation primary energy use of a case-study apartment building built to conventional and passive house standard, both with and without VHR, and using different end-use heating systems including electric resistance heating, bedrock heat pump and district heating based on combined heat and power (CHP) production. VHR increases the electrical energy used for ventilation and reduces the heat energy used for space heating. Significantly greater primary energy savings is achieved when VHR is used in resistance heated buildings than in district heated buildings. For district heated buildings the primary energy savings are small. VHR systems can give substantial final energy reduction, but the primary energy benefit depends strongly on the type of heat supply system, and also on the amount of electricity used for VHR and the airtightness of buildings. This study shows the importance of considering the interactions between heat supply systems and VHR systems to reduce primary energy use in buildings.     

Enhanced supervision strategies for effective reduction of building energy consumption--A case study of Ningbo

The purpose of this paper is to investigate the reasons for ever growing energy consumption in buildings and to give enhanced supervision strategies for reduction of building energy consumption compared to regular ones. A case study of Ningbo city was used to make a detail analysis. Several factors were determined as the reasons for ever growing building energy consumption including climate change, household electricity load increase, the growth of real estate, fast-growing household electrical appliances, high energy consumption in existing buildings, changes in industrial structure and the lack of enhanced government supervision. Then the discussion of suitable countermeasures shows that only enhanced supervision strategies are currently applicable. Finally, it is concluded that enhanced government supervision strategies, including the establishment of a strict control system for new built buildings through information integration and encryption, establishing an energy efficiency supervision system of large-scale public building and a carrot-and-stick approach with added expert checklist for the building application of renewable energy, showed great advantages in promoting building energy efficiency in Ningbo, compared with other cities. These supervision strategies are applicable in other cities as they are in the similar situations in the enforcement of building energy efficiency.     

Sensitivity of the total heat loss coefficient determined by the energy signature approach to different time periods and gained energy

In order to identify buildings that have energy saving potential there is a need for further development of robust methods for evaluation of energy performance as well as reliable key energy indicators. To be able to evaluate a large database of buildings, the evaluation has to be founded on available data, since an in-depth analysis of each building would require large measurement efforts in terms of both parameters and time. In practice, data are usually available for consumed energy, water, and so on, namely consumption that the tenants or property holder has to pay for. In order to evaluate the energy saving potential and energy management, interesting key energy indicators are the total heat loss coefficient K_tot (W/K), the indoor temperature (T_i), and the utilisation of the available heat (solar radiation and electricity primarily used for purposes other than heating). The total heat loss coefficient, K_tot, is a measure of the heat lost through the building's envelope, whereas T_i and the gained energy reflect the user's behaviour and efficiency of the control system.In this study, a linear regression approach (energy signature) has been used to analyse data for 2003-2006 for nine fairly new multifamily buildings located in the Stockholm area, Sweden. The buildings are heated by district heating and the electricity used is for household equipment and the buildings’ technical systems. The data consist of monthly energy used for heating and outdoor temperature together with annual water use, and for some buildings data for household electricity are also available. For domestic hot water and electricity, monthly distributions have been assumed based on data from previous studies and energy companies. The impact on K_tot and T_i of the time period and assumed values for the utilised energy are investigated.The results show that the obtained value of K_tot is rather insensitive to the time period and utilised energy if the analysis is limited to October-March, the period of the year when the solar radiation in Sweden yields a minor contribution to heating. The results for the total heat loss coefficient were also compared to the calculations performed in the design stage; it was found that K_tot was on average 20% larger and that the contribution to heating from solar radiation was substantially lower than predicted. For the indoor temperature, however, the utilised energy had a large impact.With access to an estimate of K_tot and T_i, an improved evaluation of the energy performance may be achieved in the Swedish real estate market. At present the measure commonly used, despite the fact that monthly data is available, is the annual use of energy for space heating per square metre of area to let.     

Impact of lifestyle on the energy demand of a single family house

The building sector is one of the highest energy consumers in Austria. The potential to save energy in existing buildings is very high. Current Austrian policy incentives encourage home owners to renovate buildings to meet the European requirements, reduce energy consumption, and reduce CO₂ emissions. Nevertheless, there are often discrepancies between the measured and calculated energy consumption results despite efforts to take parameters into account such as the exact geometry and thermal properties of the building, energy demand for hot water, heating, cooling, ventilation systems, and lighting in the planning phase for selecting the best reconstruction option. To find the answer to this problem, many buildings are carefully investigated with the help of measurements, interviews, and simulations. This paper presents the analysis and results of the investigation of the impact of lifestyle on the energy demand of a single family house. The impact on energy performance of the most important parameters was observed by systematically changing parameters such as changing from a decentralized to a centralized heating system, considering various technologies and fuels for producing electricity and heat, use of renewable energy sources. Different occupant behaviours were changed systematically. The effects of these measures are analysed with respect to primary energy use, CO₂ emissions and energy costs. The results of these investigations show that the lifestyle and occupants’ living standard is mainly responsible for the differences between the calculated and measured energy consumption.