Économies d'énergie dans les logements déjà construits

Dans l'un des projets pilotes financés par le Swedish Council of Building Research, le Service de la Technologie du Bâtiment de l'Institut Royal de la Technologie de Stockholm a montré comment la consommation d'énergie pouvait être réduite de plus de 50 % dans un groupe d'immeubles type de trois étages construit vers 1940. Les niveaux d'isolation thermique y étaient faibles par rapport aux normes suédoises – les murs et les toitures ayant des coefficients de transmission thermique de 1,2 W/m.².°C — et la consommation de fuel y atteignait 60 litres par m² de surface habitable nette.     

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.     

Real-life energy use in the UK: How occupancy and dwelling characteristics affect domestic electricity use

The patterns of electricity consumption were studied for 27 representative dwellings in Northern Ireland. The type of dwelling, its location, ownership and size, household appliances, attributes of the occupants including number of occupants, income, age and occupancy patterns have differing but significant impacts on electricity consumption. A clear correlation was found between average annual electricity consumption and floor area. The monthly consumption of detached houses is between 3.57 and 5.17 kWh m⁻²; semi-detached between 3.44 and 4.59 kWh m⁻² and terraced houses between 2.5 and 3.9 kWh m⁻². The average winter consumption exceeded the average summer consumption by 1.59 kWh m⁻² for detached, by 1.16 kWh m⁻² for semi-detached and by 1.78 kWh m⁻² for terraced houses. The difference in the annual demand on the grid between detached and terraced houses is between 24 and 30%. The electricity consumption per person decreases as the number of occupants increases. This is particularly significant in large dwellings but smaller numbers of occupants.     

Current wheeze,asthma, respiratory infections,and rhinitis among adults in relation to inspection data and indoor measurements in single‐family houses in Sweden—The BETSI study

In the Swedish Building Energy, Technical Status and Indoor environment study, a total of 1160 adults from 605 single‐family houses answered a questionnaire on respiratory health. Building inspectors investigated the homes and measured temperature, air humidity, air exchange rate, and wood moisture content (in attic and crawl space). Moisture load was calculated as the difference between indoor and outdoor absolute humidity. Totally, 7.3% were smokers, 8.7% had doctor’ diagnosed asthma, 11.2% current wheeze, and 9.5% current asthma symptoms. Totally, 50.3% had respiratory infections and 26.0% rhinitis. The mean air exchange rate was 0.36/h, and the mean moisture load 1.70 g/m³. Damp foundation (OR=1.79, 95% CI 1.16‐2.78) was positively associated while floor constructions with crawl space (OR=0.49, 95% CI 0.29‐0.84) was negatively associated with wheeze. Concrete slabs with overlying insulation (OR=2.21, 95% CI 1.24‐3.92) and brick façade (OR=1.71, 95% CI 1.07‐2.73) were associated with rhinitis. Moisture load was associated with respiratory infections (OR=1.21 per 1 g/m³, 95% CI 1.04‐1.40) and rhinitis (OR=1.36 per 1 g/m³, 95% CI 1.02‐1.83). Air exchange rate was associated with current asthma symptoms (OR=0.85 per 0.1/h, 95% CI 0.73‐0.99). Living in homes with damp foundation, concrete slabs with overlying insulation, brick façade, low ventilation flow, and high moisture load are risk factors for asthma, rhinitis, and respiratory infections.     

Application

Domestic demands account for about 40 per cent of total energy supplies in Sweden. This article reviews research by the Building Technology Division of the Swedish Royal Institute of Technology over many years into the thermal behaviour of houses. It highlights the importance of effective insulation and of solar heat gains in particular situations, entailing modifications to conventional design calculations.     

Designing houses for energy conservation

Domestic demands account for about 40 per cent of total energy supplies in Sweden. This article reviews research by the Building Technology Division of the Swedish Royal Institute of Technology over many years into the thermal behaviour of houses. It highlights the importance of effective insulation and of solar heat gains in particular situations, entailing modifications to conventional design calculations.     

Transfer of 137Cs from Chernobyl debris and nuclear weapons fallout to different Swedish population groups

Data from measurements on the body burden of ¹³⁴Cs, ¹³⁷Cs and ⁴⁰K in various Swedish populations between 1959 and 2001 has been compiled into a national database. The compilation is a co-operation between the Departments of Radiation Physics in Malmö and Göteborg, the National Radiation Protection Authority (SSI) and the Swedish Defense Research Agency (FOI). In a previous study the effective ecological half time and the associated effective dose to various Swedish populations due to internal contamination of ¹³⁴Cs and ¹³⁷Cs have been assessed using the database. In this study values of human body burden have been combined with data on the local and regional ground deposition of fallout from nuclear weapons tests (only ¹³⁷Cs) and Chernobyl debris (both ¹³⁴Cs and ¹³⁷Cs), which have enabled estimates of the radioecological transfer in the studied populations.The assessment of the database shows that the transfer of radiocesium from Chernobyl fallout to humans varies considerably between various populations in Sweden. In terms of committed effective dose over a 70 y period from internal contamination per unit activity deposition, the general (predominantly urban) Swedish population obtains 20-30 μSv/kBq m^− 2. Four categories of populations exhibit higher radioecological transfer than the general population; i.) reindeer herders (∼700 μSv/kBq m^− 2), ii.) hunters in the counties dominated by forest vegetation (∼100 μSv/kBq m^− 2), iii.) rural non-farming populations living in sub-arctic areas (40-150 μSv/kBq m^− 2), and iv.) farmers (∼50 μSv/kBq m^− 2). Two important factors determine the aggregate transfer from ground deposition to man; i.) dietary habits (intakes of foodstuff originating from natural and semi-natural ecosystems), and ii.) inclination to follow the recommended food restriction by the authorities. The transfer to the general population is considerably lower (∼a factor of 3) for the Chernobyl fallout than during the 1960s and 70s, which is partly explained by a higher awareness of the pathways of radiocaesium to man both by the public and by the regulating authorities, and by the time-pattern of the nuclear weapons fallout during the growth season in Sweden.     

Lighting energy consumption in ultra-low energy buildings: Using a simulation and measurement methodology to model occupant behavior and lighting controls

As building owners, designers, and operators aim to achieve significant reductions in overall energy consumption, understanding and evaluating the probable impacts of occupant behavior becomes a critical component of a holistic energy conservation strategy. This becomes significantly more pronounced in ultra-efficient buildings, where system loads such as heating, cooling, lighting, and ventilation are reduced or eliminated through high-performance building design and where occupant behavior-driven impacts reflect a large portion of end-use energy. Further, variation in behavior patterns can substantially impact the persistence of any performance gains. This paper describes a methodology of building occupant behavior modeling using simulation methods developed by the Building Energy Research Center (BERC) at Tsinghua University using measured energy consumption data collected by the University of Washington Integrated Design Lab (UW IDL). The Bullitt Center, a six-story 4831 m² (52,000 ft²) net-positive-energy urban office building in Seattle, WA, USA, is one of the most energy-efficient buildings in the world (2013 WAN Sustainable Building of the Year Winner). Its measured energy consumption in 2015 was approximately 34.8 kWh/(m²?yr) (11 kBtu/(ft²?yr)). Occupant behavior exerts an out-sized influence on the energy performance of the building. Nearly 33% of the end-use energy consumption at the Bullitt Center consists of unregulated miscellaneous electrical loads (plug-loads), which are directly attributable to occupant behavior and equipment procurement choices. Approximately 16% of end-use energy is attributable to electric lighting which is also largely determined by occupant behavior. Key to the building’s energy efficiency is employment of lighting controls and daylighting strategies to minimize the lighting load. This paper uses measured energy use in a 330 m² (3550 ft²) open office space in this building to inform occupant profiles that are then modified to create four scenarios to model the impact of behavior on lighting use. By using measured energy consumption and an energy model to simulate the energy performance of this space, this paper evaluates the potential energy savings based on different occupant behavior. This paper describes occupant behavior simulation methods and evaluates them using a robust dataset of 15 minute interval sub-metered energy consumption data. Lighting control strategies are compared via simulation results, in order to achieve the best match between occupant schedules, controls, and energy savings. Using these findings, we propose a simulation methodology that incorporates measured energy use data to generate occupant schedules and control schemes with the ultimate aim of using simulation results to evaluate energy saving measures that target occupant behavior.     

Effects of energy retrofits on Indoor Air Quality in multifamily buildings

We assessed 45 multifamily buildings (240 apartments) from Finland and 20 (96 apartments) from Lithuania, out of which 37 buildings in Finland and 15 buildings in Lithuania underwent energy retrofits. Building characteristics, retrofit activities, and energy consumption data were collected, and Indoor Air Quality (IAQ) parameters, including carbon monoxide (CO), nitrogen dioxide (NO₂), formaldehyde (CH₂O), selected volatile organic compounds (benzene, toluene, ethylbenzene, and xylenes (BTEX), radon, and microbial content in settled dust were measured before and after the retrofits. After the retrofits, heating energy consumption decreased by an average of 24% and 49% in Finnish and Lithuanian buildings, respectively. After the retrofits of Finnish buildings, there was a significant increase in BTEX concentrations (estimated mean increase of 2.5 µg/m³), whereas significant reductions were seen in fungal (0.6‐log reduction in cells/m²/d) and bacterial (0.6‐log reduction in gram‐positive and 0.9‐log reduction in gram‐negative bacterial cells/m²/d) concentrations. In Lithuanian buildings, radon concentrations were significantly increased (estimated mean increase of 13.8 Bq/m³) after the retrofits. Mechanical ventilation was associated with significantly lower CH₂O concentrations in Finnish buildings. The results and recommendations presented in this paper can inform building retrofit studies and other programs and policies aimed to improve indoor environment and health.     

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.     

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.     

Evening office lighting – visual comfort vs. energy efficiency vs. performance?

During the study presented in this article, we compared two highly energy-efficient lighting scenarios for evening office lighting (i.e. electric lighting that is typically used for approxiamately 2 h in the evening). The first of these lighting scenarios (referred to as “Reference”-scenario, Lighting Power Density or LPD of 4.5 W/m²) has been successfully in use in many office rooms of the Solar Energy and Building Physics Laboratory’s experimental building, located on the campus of the Swiss Federal Institute of Technology in Lausanne, for several years. The second lighting scenario (referred to as “Test”-scenario, Lighting Power Density of 3.9 W/m²) is more energy-efficient, creates higher workplane illuminances but leads to an increased risk of discomfort glare. The aim of this study was to meticulously compare the two lighting scenarios in order to find a lighting solution for evening office lighting that offers an optimal trade-off between energy-efficiency, visual comfort and visual performance.     

Swedish solar heating with seasonal storage—design,performance and economy

At the present time two Swedish group solar heating plants with seasonal storage, connected to residential areas with about 50 single-family houses, have been in operation for 4 years. The Lambohov Plant has a total of 2700 m² of flat plate collectors and a 10 000 m³ rock pit store. The Ingelstad plant has a total of 1300 m² of concentrating collectors and a 5000 m³ free-standing tank. The emphasis of the assessment has been on system performance as a whole. Most of the emphasis has been placed on general conclusions concerning technology and economy for seasonal storage plants.     

Assessment of fog collection as a sustainable water resource in the southwest of the Kingdom of Saudi Arabia

The Kingdom of Saudi Arabia (KSA) is an arid dessert with less than 100 mm yearly rainfall in addition to a high‐water consumption per capita. The collection of fog water is a simple and sustainable technology and may offer a supplementary water supply. Data were collected for a whole year from the Rayda reserve weather station, and two standard fog collectors (SFCs) were installed near the weather station. The results indicated that the average water collected by the local mesh was 6.7 L/m²/day, compared with 5.5 L/m²/day collected by the imported mesh. The highest quantity of water was collected in March by the local mesh, at 22 L/m²/day. The effectiveness of the fog collection was calculated and compared with the international standards. The obtained results indicate that fog can be utilized as a supplementary water source for the agriculture sector in the southwest KSA.     

Case study of data centers’ energy performance

This paper addresses the issue of energy performance of data centers by closely examining energy use of two data centers in commercial office buildings. The primary objective of the study is to examine an empirical energy use pattern of data centers under tropical climatic conditions, and give guidance for data centers’ design, operation and maintenance and retrofitting to achieve better energy performance. Actual energy use characteristics, design criteria, and energy and cost saving potentials were analyzed and compared between two data centers. Methodology of energy performance evaluation of data centers was discussed. The study concludes that data centers were high energy consuming areas in commercial office buildings—energy consumptions of approximately 3000 kWh/(m² year) and 2000 kWh/(m² year), respectively, were observed in the case studies. Power demands were often grossly over-provided in these facilities. This leaded to substantial increase in capital and running cost, which can be wasteful. Disparity in energy performance between case studies demonstrated the need for design guidelines and practical benchmarking. In one case study, approximately 56% (1.2 GWh/year) of energy consumption could be conserved through efficient designs of base infrastructure and energy consuming systems, as compared to better practice. The predicted cost saving is more than US$ 80,000 per year.     

Predicted versus observed heat consumption of a low energy multifamily complex in Switzerland based on long-term experimental data

The “Solar Complex of Plan-les-Ouates” is a traditional multifamily building with some commercial and administrative areas. It was designed to consume a minimum amount of thermal energy by combining several renewable energy systems (1400 m² of solar roof, buried pipe and exhausted air heat exchangers) with an optimised envelope and electrical equipment. Initially predicted to consume 160 MJ/m² per year of gas, a gas energy use index (per unit heated floor area) of 246 MJ/m² per year was measured. The energy analysis of the building, based on a 3-year period of monitoring, brought up the most relevant points that explain this difference: the real conditions of utilisation (such as the interior temperature) and the real performance of the complete technical system are not taken into account in the theoretical value. Both technical and economical aspects of the renewable energy systems were analysed in detail. An important lesson learned from this experiment is that the energy concept of buildings must be simple and consistent and the complexity of the technical installations must be carefully managed from the design-stage to the exploitation. Detailed monitoring of innovative low-energy buildings is recommended to understand the possible discrepancies between theoretical and real heat consumption and to improve the transfer of new energy technologies to large-scale real constructions.     

The estimation of energy consumption and CO2 emission due to housing construction in Japan

Basic sector classification Input/Output Tables of Japan (Research Committee of International Trade and Industry, Tokyo, Japan, 1988) were applied to quantify the total energy consumption and CO₂ emission including direct and indirect effects due to the construction of various types of houses. As a result, energy consumption for construction is calculated as 8–10 GJ per square meter of floor area for multi-family SRC (steel reinforced concrete) houses, 3 GJ for wooden single-family houses, 4.5 GJ for lightweight steel structure single-family houses. CO₂ emission resulting from construction is 850, 250 and 400 kg/m², respectively.     

A Life-Cycle Cost Comparison of Exit Stairs and Occupant Evacuation Elevators in Tall Buildings

Recent changes in the International Building Code (IBC) require a third exit stair for buildings in excess of 420 ft (128 m) high. Additionally, the new code provision allows for occupant evacuation elevators (OEE) to be used as an alternative to the third stair, provided the passenger elevator be protected in such a way to facilitate safe building evacuation. In this study, we evaluate the life-cycle costs of these alternative means of egress, using two prototypical building designs. Building ‘42F’ is a 42 floor, 504 ft (154 m) high building with a total floorspace of 1.68 million ft² (0.16 million m²). Building ‘75F’ is a 75 floor, 900 ft (274 m) high building with a total floorspace of 3.38 million ft² (0.31 million m²), including an 8403 ft² (781 m²) sky lobby. The life-cycle cost of the OEE is compared to two exit stair designs, differentiated by width: 44 in. (112 cm) and 66 in. (168 cm). The wider exit stair conforms with another change to the IBC that requires the increase in width of exit stairs by 50% in new sprinklered buildings. The results of the economic analysis demonstrate that: (1) an additional exit stair is a cost-effective alternative to the installation of OEE on a first-cost basis; and (2) OEE are a cost-effective alternative to the installation of an additional exit stair on a life-cycle cost basis when rental rates are moderate to high and when discount rates are moderate to low.     

The Saskatchewan conservation house: Some preliminary performance results

The Saskatchewan Conservation House, a low-energy-consumption solar-heated residential structure, began operation in December 1977. Monitoring of the house began in January 1978. The house has been operated as a demonstration dwelling seven days a week, and consequently monitoring conditions have been less than ideal, with approximately 1,000 visitors per week passing through the house. Monitoring of the energy consumption of the dwelling indicates that the design objective — a heat loss rate of 81 Watts per degree Celsius temperature difference between outside and inside — has been met and improved upon. An average Regina house has a heat loss rate of approximately 250 Watts/°C. The system uses 17.8 m² of vacuum tube collectors. As the system was not started until mid-December, 1977, it was not possible to provide 100% solar heating during this winter period. Approximately three Gigajoules of thermal energy can be stored in the 12,700-litre storage tank. Based on the measured performance of the house, a ‘space-heating requirement of 5.1 Gigajoules per year (4.8 million Btu) would be needed to heat the house under normal occupancy conditions. The system is designed to provide 100% of this space-heating requirement.     

Problems with the Moscow office

When the new Office Building for the United States Embassy in Moscow was in the final construction stage, visible defects caused work on the building to be suspended; a detailed structural analysis was then carried out by the NBS Center for Building Technology. Its report highlights the problems that can arise both with a structural design — such as guarding against buckling and progressive collapse — and with the detailed execution of that design.