European residential buildings and empirical assessment of the Hellenic building stock,energy consumption,emissions and potential energy savings

The existing building stock in European countries accounts for over 40% of final energy consumption in the European Union (EU) member states, of which residential use represents 63% of total energy consumption in the buildings sector. Consequently, an increase of building energy performance can constitute an important instrument in the efforts to alleviate the EU energy import dependency (currently at about 48%) and comply with the Kyoto Protocol to reduce carbon dioxide emissions. This is also in accordance to the European Directive (EPBD 2002/91/EC) on the energy performance of buildings, which is currently under consideration in all EU member states. This paper presents an overview of the EU residential building stock and focuses on the Hellenic buildings. It elaborates the methodology used to determine the priorities for energy conservation measures (ECMs) in Hellenic residential buildings to reduce the environmental impact from CO₂ emissions, through the implementation of a realistic and effective national action plan. A major obstacle that had to overcome was the need to make suitable assumptions for missing detailed primary data. Accordingly, a qualitative and quantitative assessment of scattered national data resulted to a realistic assessment of the existing residential building stock and energy consumption. This is the first time that this kind of aggregate data is presented on a national level. Different energy conservation scenarios and their impact on the reduction of CO₂ emissions were evaluated. Accordingly, the most effective ECMs are the insulation of external walls (33–60% energy savings), weather proofing of openings (16–21%), the installation of double-glazed windows (14–20%), the regular maintenance of central heating boilers (10–12%), and the installation of solar collectors for sanitary hot water production (50–80%).     

Renovation of existing office buildings in regard to energy economy: An example from Ankara,Turkey

Unit energy consumption of existing buildings in Turkey is excessive. While average energy consumption of residential buildings in Europe is 100 kWh/m² per year, it is about 200 kWh/m² per year in Turkey. The principle reason for this, is that there was not any regulation on thermal insulation issues until recent years. However, the fiscal value of total energy consumption in residential buildings is about $2.5 billion. Recent research has shown that 40% of this energy consumption could be saved, provided that using energy efficiently. Furthermore, every reduction in energy-usage has a significant influence on environmental protection and CO₂ emissions. This study has focused on energy efficiency in a building of public sector that had been inaugurated in 1988 in Ankara. During the pre-investigative step, it has been determined that 47% of total energy consumption of the building could be saved.     

基于全生命周期分析的北方农村住宅被动式集热墙体的环境影响分析

该文采用全生命周期的分析方法,比较在采用相同保温措施的情况下,与普通保温墙体相比,三种形式的被动集热墙在全寿命周期的范围内的采暖能源消耗、温室气体及固体废弃物排放情况.通过比较分析可以看出,直接受益式和附加阳光间式集热墙体在能源消耗、温室气体和固体废弃物的排放量上均小于对比房,在环境影响上具有明显的优越性;集热蓄热墙的...     

Energy consumption and the potential of energy savings in Hellenic office buildings used as bank branches—A case study

Energy performance of non-residential buildings and in particular of office buildings used as bank branches is very limited. This paper presents new data from 39 representative bank branches and results from a more in-depth analysis of information from energy audits in 11 typical bank branches throughout Greece. The data was used to derive practical energy benchmarks and assess various energy conservation measures. Accordingly, the average annual total energy consumption is 345 kWh/m². The breakdown of the different end-uses reveals that HVAC averages 48% of the final energy consumption, lighting averages 35% and other office and electronic equipment average 17%. The most effective energy conservation measures reach annual energy savings of 56 kWh/m² by regulating the indoor set point temperature, while the use of HF electronic ballasts and CFL lamps may save about 22 kWh/m² and 29 kWh/m² with and without the use of the external marquee sign, respectively.     

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.     

Transport,Housing and Urban Form: The Life Cycle Energy Consumption and Emissions of City Centre Apartments Compared with Suburban Dwellings

Buildings in cities and the activities carried out therein use a significant proportion of a nation's energy consumption and produce substantial quantities of greenhouse gases in the process. Residential buildings are a large contributor, partially as a result of the transport and housing activities of households. In this study, life cycle analysis is used to calculate the total transport and housing energy and emissions from a sample of 41 households in apartment buildings in the city centre of Adelaide, Australia and compare them with suburban households. The purpose of this is to determine whether the urban density option of higher rise dwellings offers a lower environmental impact than conventional housing. The analysis includes delivered energy and greenhouse gas emissions generated by motorised travel and activities within the dwellings, and the energy and emissions embodied in household motor vehicles and the apartment buildings. The total delivered energy consumption of apartment households was found to be lower than suburban households due mainly to higher car usage, particularly in the outer suburbs. However, the analysis of total greenhouse gas emissions provided a somewhat different comparison especially when they were considered on a per capita basis. The total per capita emissions for apartment households varied considerably but, on average, exceeded those of both the inner and outer suburban households. This resulted from lower occupancy rates and higher emissions arising from higher dwelling operational and embodied energy consumption. Overall, it cannot be assumed that centralised, higher density living will deliver per capita emission reductions for residents, once the combined per capita life cycle emissions from housing and transport have been accounted for. A more vigorous educational, promotional and regulatory approach is required to achieve greater operational and embodied energy efficiency in apartment buildings to fully realise the emissions-reducing potential of such buildings in centralised locations.

     

Energy conservation and retrofitting potential in Hellenic hotels

Energy consumption data from 158 Hellenic hotels and estimated energy savings that result from the use of practical retrofitting techniques, materials and new energy efficient systems are presented. The data were collected during an extensive energy audit of buildings that was carried out in Hellas, within the frame of a National Energy Programme sponsored by the CEC VALOREN Programme, for energy conservation in buildings. During this short monitoring campaign and on-site visits of a trained panel of engineers to each building, all information related to the building's construction, heating, cooling and lighting systems, and all other mechanical and electrical systems, was collected. The main results and energy characteristics of cooling, heating and lighting on energy consumption and performance are discussed. The annual average total energy consumption in hotels is 273 kWh/m², one of the highest among all categories of buildings. Several scenarios for possible interventions to the building's outer envelope, heating, cooling and lighting systems are proposed and evaluated, in order to assess the effectiveness of various energy conservation techniques. Based on the results from several simulations, it is concluded that it is possible to reach an overall 20% energy conservation.     

Universelle Energiekennzahlen für Deutschland — Teil 3: Spezifischer Energieverbrauch für zentrale Warmwasserbereitung und Relation zum Heizenergieverbrauch

Die Universellen Energiekennzahlen für Deutschland beinhalten 1/4 Million Gebäude‐Energieverbrauchskennzahlen der BRUNATAMETRONA‐Gruppe, welche während der vergangenen sechs Jahre erhoben wurden. In bisherigen Analysen wurde der Verbrauch für Raumheizung und für zentrale Warmwasserbereitung zusammengefasst. Hier wird der Energieverbrauch für die zentrale Warmwasserbereitung aufgeschlüsselt und adressiert dessen steigende Bedeutung am Gesamtenergieverbauch im Kontext des allgemein verbesserten Sanierungsstandes und der gestiegenen Energieeffizienz von Wohngebäuden. Der typische absolute Energieverbrauch zur Warmwasserbereitung reduziert sich von wenig energieeffizienten Gebäuden hin zu sehr energieeffizienten Gebäuden um gut die Hälfte, nämlich von etwa 40 kWh m^—2 a^—1 auf etwa 15 kWh m^—2 a^—1 (Mediane), während andererseits der relative Anteil des Energiebedarfs zur Warmwasserbereitung von 15 auf 35 % und damit auf mehr als das Doppelte ansteigt. Die Erkenntnis, dass die Warmwasserbereitung in gut wärmegedämmten Gebäuden ein Drittel des Heizenergieverbrauchs übersteigen kann, unterstreicht die Notwendigkeit der verbrauchsgerechten Erfassung von Warmwasser für eine möglichst große Verteilgerechtigkeit der Energiekosten und eine exakte Abgrenzung der Warmwasserbereitung von der Raumheizung für energetische Analysen. Zusätzlich wird eine Methode der angewandten Mathematik zur automatisierten Kennzahlbildung für beliebige Datengesamtheiten vorgestellt. Universal energy ratings for Germany — Part 3: specific energy consumption for central water heating and the relation to heating energy consumption. The universal energy ratings for Germany include about a quarter of a million energy consumption figures for buildings recorded by the BRUNATA‐METRONA Group over the last six years. In previous analyses the consumption for space heating and central hot water heating have been combined. Now figures have been broken down to show the energy consumption for central water heating, reflecting its increasing significance to overall energy consumption in the context of the general improvements in renovation levels and the increased energy efficiency of residential buildings. The typical absolute energy consumption for water heating is reduced from buildings with low energy efficiency levels to very energy‐efficient buildings by more than half, i.e. around 40 kWh m^—2 a^—1 compared with around 15 kWh m^—2 a^—1 (median values), while the relative proportion of the energy consumption used for water heating rises from 15 % to 35 %, more than double. The finding that water heating in well thermally‐insulated buildings can represent a third of the heating energy consumption, and in future may rise to as much as half, underlines the necessity of determining the amount of hot water according to use, giving a breakdown of energy costs that is as accurate as possible and precisely differentiating water heating from space heat ing for energy analysis purposes. In addition, an applied mathematics method is proposed for the automated compilation of figures for any desired body of data.     

Successful greenhouse gas mitigation in existing Australian office buildings

Frequent site energy consumption auditing is a potential strategy to mitigate greenhouse gas (GHG) emissions from existing buildings. Such a strategy has been practised in Australia for nearly 15 years. This paper documents and analyses the effect of repetitive audits on measured site energy consumption. Using a self-constructed database of over 3500 audited disclosures representing over 800 unique office buildings, empirical models demonstrate that measured site energy consumption declines, on average, over the first five re-certification periods. The results also suggest a market average post-certification equilibrium in Australia of approximately 430?MJ/m²/year (120?kWh/m²/year) within approximately six years, if all else – including green management strategy – is held constant. Since GHG emissions from buildings in Australia are highly correlated with site energy consumption, such a result is comparable with meeting 50-year GHG mitigation targets reliant on the implementation of existing technologies. This suggests that repetitive auditing is a successful approach for motivating owners to invest in existing energy efficiency technologies.     

Opportunities for reversible chillers in office buildings in Europe

Europe with more than 600 millions of square meters of air-conditioned office buildings offers an opportunity to save energy and reduce CO₂ emissions by reconverting chillers into reversible heat pumps in office buildings. One of the questions asked in the framework of the IEA ECBCS Annex 48 is how to assess the energy saving potential and how to identify the most interesting building cases. The methodology proposed here is based on the simulation of office buildings representative of the building stock. The energy consumption has been simulated for different office building types in five European climatic zones on the one hand with boilers for heating and chillers for cooling, and on the other hand with reversible chillers plus back-up boilers. The results of the simulations in terms of energy consumption allow us to assess the primary energy savings and CO₂ emission reduction in Europe by reconverting chillers into reversible heat pumps. The results show that the potential of annual primary energy savings and annual CO₂ emission reduction are about 8 TWh_PE and 3 millions of tons of CO₂ in Europe-15. Even if the temperature level in terminal units can be solved using the cooling coil instead of the heating coil, a back up boiler turns generally out to be required for the coldest days in the year or when simultaneous heating and cooling demands occur.     

“3‐Liter‐Haus” im Bestand – Messkonzept und Messergebnisse von 3 Heizperioden

Energetic renovation of an residential building – measurement and measuring results of an “3 liter building” during 3 heating periods. In Germany 80 % of all buildings are considered “old” from the point of view of their demand of energy. They have a considerable energy consumption and environmental impact. As object of study was taken a residential building in Ludwigshafen (Germany), which besides the usual renovation works, it was renewed paying special attention to its energy requirements. The goal of the project was to convert the building into a “3 liter building” (30 kWh/m²a). To achieve this objective the heat losses by transmission were reduced, the passive solar gains were increased and the heat losses by ventilation were decreased by installing a new ventilation system with heat recovery. In the building several variables were measured during three heating periods. The measurements showed a good correlation with the average energy requirements calculated for a big building. However some of the apartments had big deviations in respect to these average values. Now regarding the coming Energy Performance Certificate as energy requirements and energy demand certificate, the question about the influence of the behaviour of each users gains importance in buildings with few apartments. The data collected during this study show interesting results, which question the Energy Performance Certificate for buildings with few apartments.     

Method for achieving hydraulic balance in typical Chinese building heating systems by managing differential pressure and flow

Hydraulic unbalance is a common problem in Chinese district heating (DH) systems. Hydraulic unbalance has resulted in poor flow distribution among heating branches and overheating of apartments. Studies show that nearly 30% of the total heat supply is being wasted in Chinese DH systems due to a lack of pressure and flow control. This study investigated using pre-set radiator valves combined with differential pressure (DP) controllers to achieve hydraulic balance in building distribution systems, and consequently save energy and reduce the emissions. We considered a multi-storey building modelled in the IDA-ICE software, along with a self-developed mathematical hydraulic model to simulate its heat performance and hydraulic performance with various control scenarios. In contrast to the situation with no pressure or flow control, this solution achieves the required flow distribution and close-to-design room temperatures, as well as 16% heat savings, 74% pump electricity savings, and proper cooling of supply water. The energy consumption savings would therefore have positive environmental impacts, and be reflected in seasonal reductions of 2.1 kg/m² CO₂, 0.02 kg/m² SO₂, and 0.01 kg/m² NO_x for 3rd step energy efficiency buildings in Beijing.     

Energy consumption and potential energy savings in old school buildings

Energy and indoor environmental audits of energy consumption and indoor air quality were taken in 24 school buildings in Slovenia. The audits show that these buildings are high energy consumers and have poor indoor air quality, as expressed by 60% of the surveyed pupils. This article deals with energy consumption in the analysed schools. The nominal heating power of boilers, and heat exchangers, which are used in district heating, show a 57% overcapacity. The heat losses of the school buildings are 89% higher than the recommended values. According to our analysis of the possible measures to improve the situation in the school buildings, it will not be possible to ensure rational energy use and good indoor air quality with low investment costs. Should we change from hot-water heating systems and natural ventilation to energy efficient blown air systems with which one device provides the comfort of both heating and air conditioning?     

Calculation of the yearly energy performance of heating systems based on the European Building Energy Directive and related CEN standards

According to the Energy Performance of Buildings Directive (EPBD) all new European buildings (residential, commercial, industrial, etc.) must since 2006 have an energy declaration based on the calculated energy performance of the building, including heating, ventilating, cooling and lighting systems. This energy declaration must refer to the primary energy or CO₂ emissions.The European Organization for Standardization (CEN) has prepared a series of standards for energy performance calculations for buildings and systems. This paper presents related standards for heating systems. The relevant CEN-standards are presented and a sample calculation of energy performance is made for a small single family house, an office building and an industrial building in three different geographical locations: Stockholm, Brussels, and Venice.The additional heat losses from heating systems can be 10-20% of the building energy demand. The additional loss depends on the type of heat emitter, type of control, pump and boiler.     

Life-cycle assessment of post-disaster temporary housing

The estimation of energy consumption and related CO₂ emissions from buildings is increasingly important in life-cycle assessment (LCA) studies that have been applied in the design of more energy-efficient building construction systems and materials. This study undertakes a life-cycle energy analysis (LCEA) and life-cycle CO₂ emissions analysis (LCCO₂A) of two common types of post-disaster temporary houses constructed in Turkey. The proposed model includes building construction, operation and demolition phases to estimate total energy use and CO₂ emissions over 15- and 25-year lifespans for container houses (CH) and prefabricated houses (PH) respectively. Energy efficiency and emission parameters are defined per?m² and on a per capita basis. It is found that the operation phase is dominant in both PH and CH and contributes 86–88% of the primary energy requirements and 95–96% of CO₂ emissions. The embodied energy (EE) of the constructions accounts for 12–14% of the overall life-cycle energy consumption. The results show that life-cycle energy and emissions intensity in CH are higher than those for PH. However, this pattern is reversed when energy requirements are expressed on a per capita basis.     

Stochastic analysis of natural gas consumption in residential and commercial buildings

Consumer consumption characteristic is an important asset for safe design and management of gas distribution networks. Different characteristics of natural gas consumption in residential and commercial buildings are studied from statistical and stochastic points of view. The technique is applied during 2008 and 2009 to a densely populated district in Tehran, Iran, with relatively large number of buildings (67,655 residential and 13,286 commercial buildings). There are different trends in the histograms of gas consumption, but there is a general trend in diagrams of probability index (the probability of gas consumption exceeding a specific value) and their regressions. The most frequent amount of gas consumption for all 45-day periods is 100 m³ as compared with the annual average of 320 m³ for residential buildings. The latter reduces to 80 m³ for the averaged periodic consumption per unit in a building. Also it seems that the most frequent amount of periodic gas consumption of residential buildings is about 31% of their respective annual average during the warm months of the year, and 150% during the cold months. Periodic consumptions less than 1500 m³ and average consumptions less than 1400 m³ are more probable in residential buildings, which are larger than that of commercial ones, but this trend reverses at higher consumption values. If actual consumption is normalized by the average consumption, the number of units in the building or the floor area, the probability index of commercial buildings is generally higher than residential ones. The binomial distribution is analytically used to predict the probability of average gas consumption exceeding 320 and 2000 m³ in two example cases of 500 and 1000 buildings.     

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.     

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.     

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.     

缓冲空间对拉萨市居住建筑冬季采暖能耗的影响

冬季现场调研与热环境测试表明,拉萨市现有居住建筑的缓冲空间能明显改善室内热环境。但当地非采暖房间冬季热环境仍较差,居住建筑采暖需求明显。当地采暖能耗与环境负荷增长趋势明显。以拉萨市常见的单元式住宅为基础建立了热工计算模型,模拟分析了南北向缓冲空间进深设计对冬季采暖能耗的影响规律。结果表明:南北向缓冲空间均能有效降低模型的采暖能耗,其中,随着南向缓冲进深增大,模型采暖能耗呈递增趋势;随北向缓冲空间进深增大,模型采暖能耗呈先降后增趋势,北向缓冲空间模型之间能耗差很小。缓冲空间优化设计模型与基础模型的能耗对比分析显示,合理设置的南北向缓冲空间能够大幅降低采暖能耗。