Are the energy efficient rates (RVRs) approximate in different climatic locations for the same building with the same reform?

This paper studies the annual heating and cooling energy consumption and the variation law with the tools of characteristic temperature method (CTM) when making the same energy-saving measures on the same building under 43 different climate conditions. It can be found that for the same building, under different climate conditions, the maximal difference in annual energy consumption is up to more than 70 times and after improving building envelope, annual heating and cooling energy reductions are greatly different under various weather conditions, which illustrates that building energy consumption and its reduction is completely dependent on climate conditions; and the energy-saving potentiality and economic value with the same measures are quite different under various climatic conditions. Nevertheless, annual energy efficient rates of cooling are approximate (33.9–39.8%) for the same building with the same energy efficient measures in 43 climate conditions with quite different climatic conditions, and those of heating are also approximate (between 16.2% and 19.5%). This paper proves again the common rule that climate conditions determine energy consumption while energy efficient rates depend on the energy efficient measures.     

Climate change impacts on building heating and cooling energy demand in Switzerland

The potential impacts of climate change on heating and cooling energy demand were investigated by means of transient building energy simulations and hourly weather data scenarios for the Zurich–Kloten location, which is representative for the climatic situation in the Swiss Central Plateau. A multistory building with varying thermal insulation levels and internal heat gains, and a fixed window area fraction of 30% was considered. For the time horizon 2050–2100, a climatic warm reference year scenario was used that foresees a 4.4 °C rise in mean annual air temperature relative to the 1961–1990 climatological normals and is thereby roughly in line with the climate change predictions made by the Intergovernmental Panel on Climate Change (IPCC). The calculation results show a 33–44% decrease in the annual heating energy demand for Swiss residential buildings for the period 2050–2100. The annual cooling energy demand for office buildings with internal heat gains of 20–30 W/m² will increase by 223–1050% while the heating energy demand will fall by 36–58%. A shortening of the heating season by up to 53 days can be observed. The study shows that efficient solar protection and night ventilation strategies capable of keeping indoor air temperatures within an acceptable comfort range and obviating the need for cooling plant are set to become a crucial building design issue.     

Degree-day building energy reference map for South Africa

The six-region climatic map used in the current South African National Standards SANS 10400XA and SANS 204 does not support quantified design decisions within the built environment or indicate the amount of cooling and heating energy required per climatic region. An alternative set of maps based on interpreted degree-days is presented and can be used for regulation and design strategies. A dataset of 21 years of hourly, 0.05-degree data was used to produce a map with discrete heating and cooling degree-day classes. The resultant zones are therefore not derived from only the dominant climatic characteristics, but from simultaneous annual heating and cooling demands. The advantage is that the new map enables adaptive building design for climates with significant diurnal or annual temperature swings, making it useful for regulators and designers. A good correlation exists between the developed degree-day indices and building energy. The majority of South Africa was found to fall within the medium heating/medium cooling zone as expected; however, the KwaZulu-Natal coastal region is within the medium cooling zone and not the expected high cooling zone. This may be due to the humidity levels that are not accounted for.     

Climate change adaptation pathways for Australian residential buildings

Climate change can significantly impact on the total energy consumption and greenhouse gas (GHG) emissions of residential buildings. Therefore, climate adaptation should be properly considered in both building design and operation stages to reduce the impact. This paper identified the potential adaptation pathways for existing and new residential buildings, by enhancing their adaptive capacity to accommodate the impact and maintain total energy consumption and GHG emissions no more than the current level in the period of their service life. The feasibility of adaptations was demonstrated by building energy simulations using both representative existing and new housing in eight climate zones varying from cold, temperate to hot humid in Australia. It was found that, in heating dominated climates, a proper level of adaptive capacity of residential buildings could be achieved simply by improving the energy efficiency of building envelop. However, in cooling dominated regions, it could only be achieved by introducing additional measures, such as the use of high energy efficient (EE) appliances and the adoption of renewable energy. The initial costs to implement the adaptations were assessed, suggesting that it is more cost-effective to accommodate future climate change impacts for existing and new houses by improving building envelop energy efficiency in cooling dominated regions, but installing on-site solar PVs instead in heating and cooling balanced regions.     

Future trends of building heating and cooling loads and energy consumption in different climates

Principal component analysis of dry-bulb temperature, wet-bulb temperature and global solar radiation was considered, and a new climatic index (principal component Z) determined for two emissions scenarios – low and medium forcing. Multi-year building energy simulations were conducted for generic air-conditioned office buildings in Harbin, Beijing, Shanghai, Kunming and Hong Kong, representing the five major architectural climates in China. Regression models were developed to correlate the simulated monthly heating and cooling loads and building energy use with the corresponding Z. The coefficient of determination (R²) was largely within 0.78–0.99, indicating strong correlation. A decreasing trend of heating load and an increasing trend of cooling load due to climate change in future years were observed. For low forcing, the overall impact on the total building energy use would vary from 4.2% reduction in severe cold Harbin (heating-dominated) in the north to 4.3% increase in subtropical Hong Kong (cooling-dominated) in the south. In Beijing and Shanghai where heating and cooling are both important, the average annual building energy use in 2001–2100 would only be about 0.8% and 0.7% higher than that in 1971–2000, respectively.     

Effectiveness of passive measures against climate change: Case studies in Central Italy

This paper focuses on the effectiveness of passive adaptation measures against climate change, in the medium (2036–2065) and long term (2066–2095), for three case studies located in Florence (central Italy). In order to identify and highlight the passive measures which can provide comfort conditions with the lowest net heating and cooling energy demand, the input assumptions consider a constant thermal comfort level and don’t take into account either the effect of HVAC system’s performance and the degradation of the materials by ageing. The study results show that, in case of poorly insulated buildings, on the medium term, the reduction of energy needed for heating could be bigger than the increase for cooling, resulting in a total annual net energy need decrease, while in the long term the opposite happens. Conversely, considering a high level of thermal insulation, due to the large increase in cooling demand, the total annual energy need rises in both periods. Furthermore, attention should be paid to internal loads and solar gains that, due to the projected climate change, could become main contributors to the energy balance. In general, since the magnitude of energy need increase for cooling and decrease for heating is very significant on the long term, and varies in function of the type of building, the passive measure adopted and the level of thermal insulation, the research results lead to pay close attention to different types of energy refurbishment interventions, that should be selected in function of their effectiveness over time.     

Optimum insulation thicknesses for building walls with respect to cooling and heating degree-hours in the warmest zone of Turkey

Thermal insulation is one of the most effective energy conservation measures for cooling and heating in buildings. Therefore, determining and selecting the optimum thickness of insulation is the main subject of many engineering investigations. In this study, the determination of optimum insulation thickness on external walls of buildings is comparatively analyzed based on annual heating and cooling loads. The transmission loads, calculated by using measured long-term meteorological data for selected cities, are fed into an economic model (P₁−P₂ method) in order to determine the optimum insulation thickness. The degree-hours method that is the simplest and most intuitive way of estimating the annual energy consumption of a building is used in this study. The results show that the use of insulation in building walls with respect to cooling degree-hours is more significant for energy savings compared to heating degree-hours in Turkey's warmest zone. The optimum insulation thickness varies between 3.2 and 3.8 cm; the energy savings varies between 8.47 and 12.19 $/m²; and the payback period varies between 3.39 and 3.81 years depending on the cooling degree-hours. On the other hand, for heating load, insulation thickness varies between 1.6 and 2.7 cm, energy savings varies between 2.2 and 6.6 $/m², and payback periods vary between 4.15 and 5.47 years.     

Climate change and building ageing impact on building energy performance and mitigation measures application:A case study in Turin,northern Italy

This study uses a building energy performance simulation to investigate the impact of predicted climate warming and the additional issue of building ageing on the energy performance for a library in Turin,Italy.The climate and ageing factors were modelled individually and then integrated together for several decades.Results from the climate-only simulation showed a decrease in thebuilding heating energy usage which outweighed the increase in the on-site cooling energy demand occurring in a warming scenario.The study revealed a high sensitivity of energy performance to building ageing,in particular due to HVAC(Heating,Ventilation and Air Conditioning) equipment efficiency degradation.Building ageing was seen to negatively affect the energy performance as it induced a further increase of the cooling energy usage in a warming climate,while it also counteracted the reduction of the heating energy usage resulting from warming.Simulations on the combination of mitigation techniques showed a number of potentially retrofit measures that would be beneficial for buildings to avoid an increase in the cooling energy usage due to climate warming.The combination of these retrofit techniques showed a potential decrease of 87.3% in the final cooling energy usage for the considered building.     

Energy simulation for a high-rise building using IDA ICE: Investigations in different climates

In this paper a model of a high-rise building is constructed in the simulation program IDA ICE. The model is based on an IFC-model of a demonstration building constructed in Ljubljana, Slovenia, as part of an EU-project, EE-high-rise. The model’s energy performance was simulated for four cities: Umeå (Scandinavia), Ljubljana (Central Europe), Sibenik (Mediterranean) and Dubai (The Persian Gulf). Furthermore, the climate envelope of the building was modified with the aim to improve the model’s energy performance in each of the regions. The results were evaluated according to the energy requirements of passive house standard by the German Passive House Institute. The analysis suggests that the reference building model, which itself incorporates several energy efficient components, was unable to meet the German passive house standard in none of the four cities (Umeå, Ljubljana, Sibenik and Dubai) studied. By providing a combination of energy saving measures, such as modifications of thermal resistance of building envelope, the building may be able to meet the passive house standard in Ljubljana. The analysis concludes that the reduction in window area results in reduction of both heating and cooling demand. Increase in the thickness of the insulation and the thermal resistance of windows reduces the space heating demand for Umeå, Ljubljana and Sibenik (not applied for Dubai) while increasing the cooling demand for these cities. Increased airtightness has marginal effect on heating and cooling demand for all investigated cities. Reduced thermal resistance of windows will decrease cooling demand for Ljubljana, Sibenik and Dubai (not applied for Umeå). Reduced insulation thickness (not applied for Umeå) will decrease cooling demand for Ljubljana and Sibenik but not for Dubai. Reducing the insulation thickness may often result in reduced cooling demand for moderately warm countries since the average outdoor temperature could be lower than the indoor temperature during part of the cooling season. In those situations a reduced insulation thickness can cause heat flow from the relatively hot inside to the colder outside. However, for hot climates like in Dubai where outdoor temperature is higher than the indoor temperature for most of the year, reducing the insulation thickness will increase the cooling demand. This result suggests that the insulation thickness must be chosen and optimized based on heating and cooling demand, internal heat gain, and outdoor climate     

Identifications: inevitability of RVRs being approximately the same under different meteorological conditions when taking the same energy-saving measures in the same building

By making comparative research on hourly, daily and monthly energy consumption differences and also on energy conservation rates of heating and cooling when taking the same energy-saving measure in the same building in typical-year meteorological conditions (WDB1) and artificial meteorological conditions (WDB2), we can find from this paper that although the hourly heating and cooling load has great differences when making the same energy efficient measure in the same building under WDB1 and WDB2, the distribution laws of hourly energy efficiency rates (RVRs) of heating and cooling are very similar. It is just the similarity that determines the inevitability of approximation of annual energy conservation rates of heating and cooling. The importance of this paper is that it reveals the common rule of building efficiency. When making the same energy-saving measure on the same type of building in different regions the annual energy consumption and its reduction of the building have a great difference between the regions and the energy conservation rates (RVRs) of the same measures are approximate. After taking some energy-saving measure on the same building in the same place, within the lifetime of the building, however different the local weather conditions over the years are, the energy consumption of different years and the energy reductions of the measure must be different. However, it can be foreseen that the energy conservation rate of any year is approximate after making energy-saving measures on the building. The reason for the above is that although climate changes between years, there is nothing more impractical in artificially modifying meteorological conditions (WDB2), which provides a powerful theoretical basis for every country to lay down design standard for energy efficiency.     

Influence of building parameters and HVAC systems coupling on building energy performance

The performance of different HVAC systems varies when coupled with different buildings. This paper examines the relationship between building heating and cooling load and subsequent energy consumption with different HVAC systems. Two common HVAC systems in use throughout the UK office building stock, variable air volume (VAV) system and fan coil (FC) with dedicated outside air system, have been coupled with a typical narrow plan office building with and without daylight control and for both cellular and open plan.The results presented in this paper clearly indicate that it is not possible to form a reliable judgment about building energy performance based only on building heating and cooling loads. For the two investigated systems, variable air volume system and fan coil with dedicated outside air system, the difference between system demand and building demand varied from over −40% to almost +30% for cooling and between −20% and +15% for heating. If a heat recovery unit is used, the difference in heating performance is even greater, rising to −70%.     

Uncertain programming of building cooling heating and power (BCHP) system based on Monte-Carlo method

Uncertainty of building energy demands has large influence on accuracy of building cooling heating and power (BCHP) programming model. Uncertain programming model is proposed to optimize BCHP system with consideration of uncertainty of energy demands. Monte-Carlo method (MCM) and mixed-integer nonlinear programming (MINLP) are integrated in the model (M-M model for short). MCM can be used to simulate the uncertainty of energy demands avoiding dimension disaster and complex calculation. Correlation between different energy demands can also be considered in the model. And facility scheme and operation strategy can be optimized simultaneously in MINLP model. A numerical example is calculated with the M-M model. Convergence rate of expected values of the variables optimized in the model is high. Influence of energy demand uncertainty is studied with investigation of expected values, standard deviations of evaluation indicators and facility capacities. Sensitivity of the parameters to energy demand uncertainty is much different. It is unnecessary to consider uncertainty of energy demands when evaluating system feasibility with indicators of annual cost saving rate and annual natural gas saving rate, for they are influenced only a little by uncertainty of energy demands. While uncertainty of energy demands must be considered when studying parameters related to assistant facilities, which are very sensitive to the uncertainty. The result is valuable for designing strategy of facility scheme.     

相同建筑相同节能措施在不同气象条件下的负荷减少率

以广州、重庆、北京等12个城市为对象,分别以DOE-2中的TMY2,DeST—h中的TRY及修改的TMY2辐射数据,构建了36组完全不同的8760h气象数据库。利用特征温度法模拟计算相同建筑在围护结构改进前后单位建筑面积的全年空调和供暖耗能量。研究发现,对所涉及的城市,尽管因三种气象数据库（36组）显著不同,导致计算出的围护结构改进前后（72组）建筑全年空调供暖负荷、负荷减小量存在很大的差异,但是在不同气象条件下对模型建筑采取相同的节能措施。各城市全年空调负荷减小率（节能率）是相近的;各个城市全年供暖负荷减小率（节能率）也是相近的。从而证明了现行各国标准均规定围护结构K限值的通常做法是完全正确的。     

夏热冬冷地区办公建筑降低供暖空调能耗的技术路径

以上海地区某办公建筑为例,基于EnergyPlus能耗模拟,探讨了围护结构性能提升和暖通空调系统优化这2条节能技术路径对夏热冬冷地区办公建筑降低供暖空调全年能耗的有效性.结果 表明:围护结构性能提升的节能潜力较小,经济性较差;单纯提高围护结构保温隔热性能并不能保证降低建筑年耗冷量,应综合分析全年供热供冷能耗确定围护结构...     

寒冷地区建筑负荷对围护结构热工参数的敏感性分析

为研究建筑围护结构属性对同一热工分区不同城市节能建筑负荷影响的敏感性,以同属于寒冷地区的兰州和郑州为研究目标所在城市,在节能65％的前提下将4种外墙、3种外窗和4种窗墙比进行组合得到了48个可能的办公建筑围护结构计算房间。分别计算了这些房间的冷负荷、热负荷和全年总负荷并分析了各热工参数对负荷的影响。通过与基准房间负荷对比,获得了具有不同热工性能的计算房间的节能率及最优的办公建筑围护结构。     

Estimating the impacts of climate change and urbanization on building performance

Over the past 15 years, much scientific work has been published on the potential human impacts on climates. For their Third Assessment Report in 2001, the United Nations International Programme on Climate Change developed a set of economic development scenarios, which were then run with the four major general circulation models (GCM) to estimate the anthropogenesis-forced climate change. These GCMs produce worldwide grids of predicted monthly temperature, cloud, and precipitation deviations from the period 1961–1990. As this period is the same used for several major typical meteorological year data sets, these typical data sets can be used as a starting point for modifying weather files to represent predicted climate change. Over the past 50 years, studies of urban heat islands (UHI) or urbanization have provided detailed measurements of the diurnal and seasonal patterns and differences between urban and rural climatic conditions. While heat islands have been shown to be a function of both population and microclimatic and site conditions, they can be generalized into a predictable diurnal and seasonal pattern. Although the scientific literature is full of studies looking at the impact of climate change driven by human activity, there is very little research on the impact of climate change or urban heat islands on building operation and performance across the world. This article presents the methodology used to create weather files which represent climate change scenarios in 2100 and heat island impacts today. For this study, typical and extreme meteorological weather data were created for 25 locations (20 climate regions) to represent a range of predicted climate change and heat island scenarios for building simulation. Then prototypical small office buildings were created to represent typical, good, and low-energy practices around the world. The simulation results for these prototype buildings provide a snapshot view of the potential impacts of the set of climate scenarios on building performance. This includes location-specific building response, such as fuel swapping as heating and cooling ratios change, impacts on environmental emissions, impacts on equipment use and longevity comfort issues, and how low-energy building design incorporating renewables can significantly mitigate any potential climate variation. In this article, examples of how heat island and climate change scenarios affect diurnal patterns are presented as well as the annual energy performance impacts for three of the 25 locations. In cold climates, the net change to annual energy use due to climate change will be positive – reducing energy use on the order of 10% or more. For tropical climates, buildings will see an increase in overall energy use due to climate change, with some months increasing by more than 20% from current conditions. Temperate, mid-latitude climates will see the largest change but it will be a swapping from heating to cooling, including a significant reduction of 25% or more in heating energy and up to 15% increase in cooling energy. Buildings which are built to current standards such as ASHRAE/IESNA Standard 90.1-2004 will still see significant increases in energy demand over the twenty-first century. Low-energy buildings designed to minimize energy use will be the least affected, with impacts in the range of 5–10%. Unless the way buildings are designed, built, and operated changes significantly over the next decades, buildings will see substantial operating cost increases and possible disruptions in an already strained energy supply system.     

Energy performance optimization of radiant slab cooling using building simulation and field measurements

Few field studies of energy performance of radiant cooling systems have been undertaken. A recently constructed 17,500 m² building with a multi-floor radiant slab cooling system in the tower was investigated through simulation calibrated with measured building energy use and meteorological data. For the very cold, dry region where the building was located, it was found that a typical floor of the tower would have had 30% lower annual energy use with a conventional variable air volume system than with the as-built radiant cooling-variable air volume combination. This was due to (1) simultaneous heating and cooling by the existing radiant cooling and air systems, (2) the large amount of free cooling possible in this climate, and (3) suboptimal control settings. If these issues were remedied and combined with improved envelope and a dedicated outdoor air system with exhaust air heat recovery, a typical floor could achieve annual energy use 80% lower than a typical floor of the existing building HVAC system. This shows that radiant thermal control can make a significant contribution to energy-efficiency, but only if the building design and operating practices complement the strengths of the radiant system.     

气候变化对中国寒冷和夏热冬暖城市建筑能耗的影响

气候变暖已对建筑全生命周期的运行状况产生了不可忽略的影响,准确评估气候变化下的建筑能耗对建筑方案设计和既有建筑的节能改造具有重要意义。进行气候变化下建筑能耗的精确预测,必须拥有未来的逐时气象数据。以寒冷地区北京和夏热冬暖地区广州为研究对象,将挑选的两个城市典型气象年为基线气候,结合全球模式下的预测气象数据,应用变形法修正TMY的气象参数,得到直至本世纪末的10个节点年逐时气象文件,并进行了全年能耗模拟,预估了两个城市的办公建筑在气候变化下建筑能耗的变化趋势。结果表明:在两种预测排放情景下,干球温度、含湿量和太阳辐射均呈增加趋势;北京采暖能耗显著降低、制冷能耗增加,总能耗减少,广州采暖能耗降低、制冷能耗显著增加,总能耗增加。     

Optimisation of solar-optical and thermal properties of buildings incorporating solar panels, emulating traditional Chinese building style

A building-integrated solar energy system, based on the traditional Chinese building (e.g., pagoda) - buildings with roofing at intermediate levels (known as eaves) - was investigated, with regard to providing for heating and cooling demands. A number of building parameters, related to energy exchange - solar absorptivity of the exterior wall, level of glazing, etc. - were optimised to minimise demand, and the orientation and tilt of the panels were selected to provide maximum energy at the times of maximum demand. Each parameter was investigated for a range of locations, in order to identify trends, which could then be applied to other locations. In most cases, solar power was sufficient to meet the cooling demands. For a number of locations, solar power provided some, but not all, of the heating loads.     

Categories of indoor environmental quality and building energy demand for heating and cooling

Maintaining suitable indoor climate conditions is a need for the occupants’ well being, while requiring very strictly thermal comfort conditions and very high levels of indoor air quality in buildings represents also a high expense of energy, with its consequence in terms of environmental impact and cost. In fact, it is well known that the indoor environmental quality (IEQ), considering both thermal and indoor air quality aspects, has a primary impact not only on the perceived human comfort, but also on the building energy consumption. This issue is clearly expressed by the European Energy Performance of Buildings Directive 2002/92/EC, together with the most recent 2010/31/EU, which underlines that the expression of a judgment about the energy consumption of a building should be always joint with the corresponding indoor environmental quality level required by occupants. To this aim, the concept of indoor environment categories has been introduced in the EN 15251 standard. These categories range from I to III, where category I refers to the highest level of indoor climate requirement. In the challenge of reducing the environmental impact for air conditioning in buildings, it is essential that IEQ requirements are relaxed in order to widen the variations of the temperature ranges and ventilation air flow rates. In this paper, by means of building energy simulation, the heating and cooling energy demand are calculated for a mechanically controlled office building where different indoor environmental quality levels are required, ranging from category I to category III of EN 15251. The building is located in different European cities (Moscow, Torino and Athens), characterized by significantly different wheatear conditions. The mutual relation between heating and cooling energy demand and the required levels of IEQ is highlighted. The simulations are performed on a typical office room which is adopted as a reference in validation tests of the European Standard EN 15265 to validate calculation procedures of energy use for space heating and cooling.