Development of a methodology for selecting office building upgrading solutions based on a test survey in European buildings

The potential for using the TOBUS methodology to select office building upgrading solutions have been investigated during field tests in 15 European office buildings in 5 European countries. The 15 office buildings represent a variety of building traditions, architectural designs, construction periods and energy and indoor performance. The buildings were audited following the TOBUS methodology developed within the project. The results of the test surveys were primarily used to improve the TOBUS methodology and secondly to suggest general upgrading solutions and energy retrofit measures for the surveyed buildings. This paper describes the development of the TOBUS methodology based on the 15 test surveys.     

TOBUS — a European diagnosis and decision-making tool for office building upgrading

The TOBUS (a decision-making tool for selecting office building upgrading solutions) methodology and software have been developed as a result of a 2-year European research project, involving eight European institutions, in the frame of the JOULE III programme of the European Commission (EC), Directorate General XII. A structured diagnosis scheme enables architects and engineers to simultaneously handle the entire complex process of office building refurbishment or retrofit with respect to deterioration, functional obsolescence of building services, energy consumption and indoor environmental quality. The software tool can then be used to define the most appropriate and cost-effective actions, to elaborate consistent refurbishment scenarios and calculate a reasonable investment budget in the early stages of a refurbishment project. This paper provides an overview of the work performed in TOBUS and an overview of the methodology and final deliverables of the project.     

Indoor environment quality and upgrading of European office buildings

Indoor environmental quality (IEQ) is an important quality aspect of office buildings, which is acknowledged in a new European methodology and software for office building refurbishment (TOBUS). In TOBUS, an inventory of complaints from occupants about IEQ is made as well as an inventory of characteristics of building and HVAC-system. Based on relations between characteristics of buildings and systems and the use of the building, different possible causes for the problems can be identified and possible actions for improvement can be selected. A relation scheme is provided with relations between objects and types, complaints of occupants in an office building, possible causes of those complaints and actions that should take away those complaints. Furthermore, a relation scheme is provided with causes and actions that cannot be related to an object. A procedure to qualify and quantify the IEQ performance of a building is given. This article describes the results of the field investigations in 12 European buildings focused on the IEQ part. Discussions and conclusions from this field study with respect to IEQ and with respect to the methods and procedures used are also presented.     

Infrared thermography for building diagnostics

The use of thermal infrared (IR) imaging is a valuable tool for inspecting and performing non-destructive testing of building elements, detecting where and how energy is leaking from a building’s envelope, collecting data for clarifying the operating conditions of hard to reach heating, ventilating and air-conditioning (HVAC) installations, identifying problems with the electrical and mechanical installations under full-load operating conditions. IR inspections involve the detection of IR electromagnetic radiation emitted by the inspected object. The collected information can be used as part of other investigative procedures to identify potential problems, quantify potential energy savings, schedule interventions and set priorities for preventive and predictive maintenance or the need for immediate service to minimise the risk of failure. This paper reviews the main areas for using IR in building diagnostics with an emphasis on how it was implemented to support office building audits following the TOBUS methodology. Representative examples from building envelope, mechanical and electrical inspections in audited Hellenic office buildings are presented to demonstrate common problems and data interpretation.     

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.     

A screening methodology for implementing cost effective energy retrofit measures in Canadian office buildings

Private and public sectors own and operate an array of office buildings that consume energy and contribute to the emission of greenhouse gases (GHG). Energy demands can be reduced by applying energy retrofit measures (ERMs) to existing buildings. The choice of ERMs involves evaluation of applicability, energy end uses and cost of application versus energy savings. This paper describes a methodology developed to screen office buildings for their current level of energy consumption and potential for retrofit application. Selection of an optimal set of ERMs is influenced by climate, occupancy, heating and cooling systems, envelope properties and building geometry. When assessing the implications of applying ERMs to a large building stock it is vital to screen the complete building set for optimal retrofit opportunities. This can be accomplished by characterizing office building stock into a manageable set of archetypes and simulating building operation using energy simulation software. Using regression analyses, a model was developed for estimating the energy consumption. Present value analysis was used to optimize the evaluation of the various ERMs. The methodology developed can be used to simplify the ranking of buildings for retrofit; to select and combine ERMs, and to plan energy and GHG reduction activities.     

Measured energy savings from residential retrofits: Updated results from the BECA-B project

This study summarizes measured data on energy savings from conservation retrofits in existing residential buildings. We have compiled building performance data on approximately 115 retrofit projects (almost twice the size of the initial study) that we put into four general categories: utility-sponsored conservation programs, low-income weatherization programs, research studies, and multifamily buildings. The sample size for each project varies widely, ranging from individual buildings to 33 000 homes. Retrofits to the building shell, principally insulation of exterior surfaces, window treatments, and infiltration-reduction measures, are the most popular, although data on various heating system retrofits are now available. The average retrofit investment per unit in multifamily buildings is approximately $695, far lower than the average of $1350 spent in single-family residences. The median annual space heat savings in the four categories range from 15 to 38 GJ. Savings achieved are typically 20%–30% of pre-retrofit space heating energy use although large variations are observed both in energy savings and in costs per unit of energy saved. Even given the wide range in savings, most retrofit projects are cost-effective. Approximately 75%–80% of the retrofit projects have costs of conserved energy below their respective space heating fuel or electricity prices.     

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%).     

Energy conservation in small enterprises

Compared to other non-residential buildings that have been widely researched, industrial buildings have higher thermal loads, higher air-change rates, longer operating hours and greater pollution control requirements. This paper presents the results of preliminary audits carried out on a sample of 12 representative small business enterprises in Greece including food, marble, wood, paper, plastic, metallurgical and service companies. Energy intensity varied from 50 to just over 300 kWh/m² with heavier industry buildings having values up to 1300 kWh/m². The successful adoption of energy conservation measures in key energy waste areas was assessed, including: (1) building envelope, (2) artificial lighting, (3) heating, ventilating and air conditioning (HVAC) and refrigeration systems, (4) space and water heating, (5) electrical and mechanical equipment and (6) distribution and transportation. It was found that businesses were more sensitized to energy conservation in the area of air conditioning followed by electromechanical equipment (important energy waste area that may yield the biggest energy conservation results, still in need of great improvement though the cost may be very high) and space/water heating; compliance with energy conservation measures was worst in the areas of artificial lighting (least important energy waste area in the case of most businesses) and the building envelope. A more detailed modeling study on a larger sample is proposed as a next step.     

大型办公建筑照明及插座系统电耗逐时使用率聚类分析

逐时使用率对于预测办公建筑照明与插座系统电耗,以及核定节能改造的节能量有十分重要的意义。选取重庆17幢办公建筑作为研究对象,根据建筑全年逐时照明与插座系统的实测电耗数据,计算各建筑全年每个工作日24h的逐时使用率。利用聚类分析方法,根据日逐时使用率的不同,将办公建筑快速分为3类。根据是否经常加班以及午休时是否关闭部分用电设备,可以快速判断办公建筑属于哪一分类。最后对3类建筑分时段计算典型逐时使用率,便于实际应用中快速查询。     

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.     

On the potential of retrofitting scenarios for offices

Within the framework of OFFICE research project the energy conservation potential of combined retrofitting actions was investigated for five building types in four different climatic regions in the European continent. The studied actions involve interventions on the building envelope, HVAC and artificial lighting systems as well as integration of passive components for heating and cooling. Interventions affecting the performance of the building in the global aspect were also assessed.The potential of retrofitting actions proposed for each building type was assessed through energy simulations using high-accuracy computer models and climatic data from 10 locations in South Mediterranean, Continental, Mid-Coastal and North Coastal Europe. Analysis of the results revealed common trends in the energy performance of different building types and permitted to extract information on the most suitable retrofitting interventions in each.     

Evaluation of the functional obsolescence of building services in European office buildings

With the support of the TOBUS software, it is now possible to evaluate, in a methodical and rigorous manner, one of the major causes of obsolescence for office buildings. The functional obsolescence is a major parameter affecting technical installations and influences the value of an office building. The tool can be used during an office building audit to examine and assess all the building services which are likely to be found in modern buildings (i.e. heating, ventilating and air conditioning (HVAC) plants, fire fighting services, electrical installations, information networks, building management systems, etc.). The selected quality assessment criteria correspond to the requirements of modern buildings, including compliance with user needs, flexibility, divisibility and maintainability, as well as conformity with building regulations. Moreover, the software is used to perform an exhaustive diagnosis of the entire building, including architectural and technical aspects, and supports the user to define and evaluate different scenarios and retrofitting actions, providing the corresponding costs.     

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.     

The use of DOE-2 to determine the relative energy performance of daylighted retail stores covered with tension supported fabric roofs

With increasing interest amongst the architectural and engineering community in daylighted buildings, there is a need to evaluate the relative energy performance of those buildings. One means of daylighting a building is to use a coated glass fiber fabric roof. With such a roof, it has been found that sufficient daylight is admitted to allow most artificial lighting to be turned off during the daytime hours. However, solar cooling loads and conductive loads may be greater than for conventionally roofed commercial buildings. With the fabric roofed buildings capable of using considerably less energy for artificial lighting, yet possibly requiring greater use of energy for space heating and cooling, the relative energy performance is a matter of trade-offs.To determine this relative energy performance of fabric roofed and conventionally roofed retail stores, a modified version of DOE-2.1A was used with weather data from 19 cities located within the United States. In the analyses, both single-layer and double-layer roofs were studied as were stores with different levels of electric power for artificial lighting. In general, the results suggest that a fabric roofed store will use less total energy than a conventional roofed store in a geographic area with a mild climate but that it will use more energy in a cold climate area.     

Heating energy consumption and resulting environmental impact of European apartment buildings

Buildings have direct environmental impacts, ranging from the use of raw materials for their construction and renovation to the consumption of natural resources, like water and fossil fuels, and the emission of harmful substances. Data on heating energy consumption were collected during the audits of 193 European residential buildings in five countries. The available data were analysed in order to assess the influence of envelope thermal insulation, age and condition of heating system, on the heating energy consumption and the resulting environmental impact. About 38% of the audited buildings have an annual heating energy consumption more than the European average (174.3 kWh/m²), about 30% of the buildings have higher airborne emissions than the European averages and 23% of the buildings have higher solid waste emissions than the European averages. Polish buildings have the highest average heating energy consumption (63% of the buildings above the European average). French and Polish buildings have the highest production of airborne emissions, while Polish buildings have the highest emissions of solid wastes.     

Virtual Building Dataset for energy and indoor thermal comfort benchmarking of office buildings in Greece

The knowledge of building stock energy data of a country is a very significant tool for energy benchmarks establishment, energy rating procedures and building classification boundaries determination, according to the Directive 2002/91/EC and its implementation in EU Member States. The lack of building energy databases in many EU Countries, including Greece, and the difficulties of collecting them lead to the investigation of other potential solutions. The aim of this paper is to present a method of a Virtual Building Dataset (VBD) creation for office buildings in Greece. The philosophy of VBD is based on the creation and simulation of random office buildings that could be found or built in Greece, taking into account the Greek constructional and operational characteristics of office buildings and Greek legislation. The VBD consists of 30,000 buildings (10,000 in each climatic zone) with their detailed constructional and operational data and of their simulation outputs: the annual specific energy consumption for heating, cooling, artificial lighting, office equipment and an indoor thermal comfort indicator. Based on VBD results the energy and indoor thermal comfort benchmarks for office building sector in Greece are assessed and presented.     

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.     

Impacts of building operational schedules and occupants on the lighting energy consumption patterns of an office space

This paper considers pre-retrofit and post-retrofit lighting energy end-use of two sub-metered office spaces. Building lighting retrofits are typically installed to reduce energy consumption and operational costs of buildings. This traditionally includes replacing lights and introducing Building Management System (BMS). Through this process, an occupant’s ability to override new computerized controls could be compromised, which can dramatically affect the overall success of the project. Therefore, the analysis focuses on the effectiveness of the lighting retrofit, influence of the BMS upgrade, occupant behavior, and the lessons learned. The analysis comprises three different phases including one pre-retrofit and two post-retrofit phases. Each of the retrofit phases lasted approximately one year, leading to the monitoring of three years of sub-metered lighting energy end-use. The results showed that when the occupants had access to the lighting switches while BMS managed the operational lighting schedule, the office area with the responsible occupant saved 23.2% compared to the pre-retrofit phase. For the second lighting retrofit phase when the occupants did not have access to the light switches, the lighting schedule operated for more than two hours after the typical work day and the occupant was not able to turn off the lights upon departure. It should be noted that there are limited numbers of studies that consider three years sub-metered lighting retrofit data with the presented granularities in this study. Similar lighting retrofit projects could benefit from the findings of this study. Finally, the results of this sub-metered lighting data could address uncertainty in the selection of lighting power density and associated schedules of building energy simulations.     

Interventions for large-scale carbon emission reductions in future UK offices

Previous work by the authors has shown the effect that changing climate and small power/lighting equipment can have on heating and cooling loads of typical existing UK offices, for a 2005 baseline. This follow-on study uses an improved office, with reduced cooling loads, and performs retrofit fabric and HVAC measures to further reduce the energy and CO₂ emissions associated. The effect of heat recovery on the proposed “2030 office” is then quantified, showing that such an office can tend towards being “passively heated”. With adaptive comfort also applied, the office CO₂ emissions are estimated for various UK locations. The measures suggest CO₂ emissions relating to heating, cooling and ventilation (HVAC) can be reduced by 61% for the specific office-type studied. The proposed measures are carried out while allowing for a change in activity between 2005 and 2030. When all factors leading to changes in energy use are accounted for, namely small power, lighting, HVAC and climate change, total CO₂ savings of 65% are estimated when compared to the 2005 baseline. In achieving these theoretical savings, the relationship between internal activity and HVAC is studied, and identified as being a crucial area if challenging CO₂ emission targets are to be reached.