Simulation of façade and envelope design options for a new institutional building

This paper presents a simulation case study of façade and envelope preliminary design options for the new Engineering building of Concordia University in Montreal. A major principle of the analysis was to create a high quality building envelope in order to optimally control solar gains, reduce heating and cooling energy demand and reduce electricity consumption for lighting, while at the same time maintain a comfortable and pleasant indoor environment. The stated approach of the design team was to aim for an energy-efficient building, employing innovative technologies and integrating concepts such as daylighting and natural ventilation. Detailed energy simulations were therefore performed from the early design stage, in order to present recommendations on the choice of façade, glazings, shading devices, lighting control options, and natural ventilation. Integrated thermal studies, a daylighting analysis and the impact of the above on HVAC system sizing were considered. Simulation results showed that, using an optimum combination of glazings, shading devices and controllable electric lighting systems, the energy savings in perimeter spaces can be substantial. Perimeter heating could be eliminated if a high performance envelope is used. The building is currently being commissioned.     

A study of energy performance and audit of commercial mall in hot-summer/warm-winter climate zone in China

The building energy performance improvement of large-scale public buildings is very important to release China’s energy shortage pressure. The aim of the study is to find out the building energy saving potentials of large-scale public and commercial buildings by energy audit. In this paper, the energy consumption, energy performance, and audit were carried out for a typical commercial mall, the so-called largest mall in Asia, located in a hot-summer and warm-winter climate zone. The total annual energy consumption reaches 210.01 kWh/m², of which lighting energy consumption accounts for 30.03 kWh/m² and the lift and elevator energy consumption accounts for 40.46 kWh/m². It is by far higher than that of the average building energy consumption in the same category. However, the annual heating, ventilation, and air-conditioning (HVAC) energy consumption is only 87.19 kWh/m² even though they run 24/7. It proves that the energy performance of the HVAC system is good. Therefore, the building energy savings potential mainly relies on reducing the excessive usage of lighting, lifts, and elevators.     

Progress and methodologies of lifecycle commissioning of HVAC systems to enhance building sustainability

Building energy consumption keeps rising in recent years due to growth in population, increasing demand for healthy, comfort and productive indoor environment, global climate changing, etc. Nowadays, the contribution from buildings toward global energy consumption is approximately 40%. Most of energy use in buildings is for the provision of heating, ventilation and air conditioning (HVAC). High-level performance of HVAC systems in building lifecycle is critical to building sustainability.As a quality-oriented process, commissioning has been recognized as a valid means to improve performance of buildings and HVAC systems in both energy and environment aspects and should be conducted regularly or continuously throughout the whole building lifecycle. At the same time, building automation systems (BAS) are now standard in most modern buildings. Besides automatic monitoring and control of building services systems, automatic commissioning is a new expectation on modern BAS to save labor, time and cost required by manual commissioning and improve the effectiveness of commissioning. This paper firstly takes a brief look at current situation of building commissioning in research and application world wide, and then summarizes state-of-the-art techniques for automatic commissioning of HVAC systems. It is concluded that, to maximize benefits from commissioning for enhancing building sustainability, more efforts should be made to develop automatic commissioning tools which can be integrated with modern BAS.     

Energy saving in the street lighting control system—a new approach based on the EN-15232 standard

The street lighting is one of major components in total energy consumption in cities. The paper is focused on a concept of street lamp control systems and function organization with remote monitoring, to reduce maintenance costs and energy consumption. A new approach to the definition of functional strategy organization for outdoor lighting systems is introduced in the paper. Proposed functional strategies are based on four efficiency classes of building automation and control systems (BACS) defined in the EN 15323 standard. They have been formulated, analysed and eventually implemented and verified in real experiment street lighting installation. This outdoor lighting system, designed by the authors, based on LonWorks (the ISO/IEC EN 14908) platform with a power line communication aimed to control high-pressure sodium lamps. The street lamps are integrated nodes of a building management system (BMS). The results of experimental tests for the proposed functional strategies, implemented with various control scenarios, show that they provide a great potential in reducing energy consumption by street lighting installations. In particular, the energy use can be reduced even by 45 % in comparison to conventional street lighting system, especially without the use of monitoring and control.     

Energy monitoring and control systems (EMCS) problems and potential solutions

An Energy Monitoring and Control System (EMCS), or Energy Management System as it is sometimes known, is primarily intended as a retrofit to existing buildings to provide more efficient control of mechanical and electrical equipment. Most existing controls for heating/ventilating/air conditioning (HVAC) equipment were designed and installed during a period of low energy cost and are not the most energy efficient. Using a computer for supervisory control allows the equipment to be operated in a more efficient manner through existing controls. In the U.S.A., primarily in the Department of Defense, significant potential benefits have been recognized for EMCS applications, including direct energy savings as well as more effective utilization of limited manpower. Unfortunately, actual implementation of systems has been fraught with problems. To overcome this, a 2-year intensive effort involving industry and government personnel has culminated in an EMCS design manual and guide specifications for four different types of EMCS, ranging from a single building controller to a network controlling hundreds of buildings. A research program has been formulated to address ways of improving hardware components, control strategies (software), and the implementation process. This paper addresses a rationale and methodology for planning, designing, installing and operating an EMCS to fully realize energy savings.     

Heat planning for fossil-fuel-free district heating areas with extensive end-use heat savings: A case study of the Copenhagen district heating area in Denmark

The Danish government plans to make the Danish energy system to be completely free of fossil fuels by 2050 and that by 2035 the energy supply for buildings and electricity should be entirely based on renewable energy sources. To become independent from fossil fuels, it is necessary to reduce the energy consumption of the existing building stock, increase energy efficiency, and convert the present heat supply from fossil fuels to renewable energy sources. District heating is a sustainable way of providing space heating and domestic hot water to buildings in densely populated areas. This paper is a theoretical investigation of the district heating system in the Copenhagen area, in which heat conservation is related to the heat supply in buildings from an economic perspective. Supplying the existing building stock from low-temperature energy resources, e.g. geothermal heat, might lead to oversized heating plants that are too expensive to build in comparison with the potential energy savings in buildings. Long-term strategies for the existing building stock must ensure that costs are minimized and that investments in energy savings and new heating capacity are optimized and carried out at the right time.     

Case study of data-oriented approach for building energy performance investigation

The key parameters that may influence building energy performance is studied by comparing the building energy data of college buildings in two different regions (the USA and China). By introducing data-orientated approach, a study of a set of on-campus building energy demand and consumption is conducted for cooling, heating and electricity. In addition, the heating, ventilation and air conditioning (HVAC) and lighting systems are studied in great detail. The breakdown analyses of the current energy consumption data are used to focus the investigation on critical issues. The analysis shows that the energy consumption of college buildings in the USA can be 3–5 times more than that of college buildings in China. The over-high energy consumption in campus buildings in the USA is mainly caused by operation schedule, system style, cooling and heating counteraction and sensor/actuator faults in the control systems, which also leads to the discussion of energy difference on the concept of “full control” or “local improvement” in building environment control. The study also indicates that the building energy efficiency can only be achieved by adjusting the demand according to natural conditions, encouraging green life behaviors, and developing relative technical solutions coordinated with the thrift culture and human behavior.     

Case study of data-oriented approach for building energy performance investigation

The key parameters that may influence building energy performance is studied by comparing the building energy data of college buildings in two different regions (the USA and China). By introducing data-orientated approach, a study of a set of on-campus building energy demand and consumption is conducted for cooling, heating and electricity. In addition, the heating, ventilation and air conditioning (HVAC) and lighting systems are studied in great detail. The breakdown analyses of the current energy consumption data are used to focus the investigation on critical issues. The analysis shows that the energy consumption of college buildings in the USA can be 3–5 times more than that of college buildings in China. The over-high energy consumption in campus buildings in the USA is mainly caused by operation schedule, system style, cooling and heating counteraction and sensor/actuator faults in the control systems, which also leads to the discussion of energy difference on the concept of “full control” or “local improvement” in building environment control. The study also indicates that the building energy efficiency can only be achieved by adjusting the demand according to natural conditions, encouraging green life behaviors, and developing relative technical solutions coordinated with the thrift culture and human behavior.     

Numerical study of a hybrid ventilation system for single family houses

The main objective of this study is to develop and test hybrid ventilation systems and control strategies that are suitable for residential buildings. Two ventilation systems were modelled: a mechanical extract ventilation system (called the reference system) and a hybrid low pressure ventilation system that can support two different types of demand control strategies (occupancy detection and CO₂ concentration). The newly developed models were assembled with the existing thermal models of the SIMBAD Building and HVAC Toolbox developed by the CSTB.A single family house located in Athens (Greece), Nice (France), Trappes (France) and finally Stockholm (Sweden) was considered as the case study. Yearly simulations were performed to assess the performance of the hybrid ventilation control strategies. The assessment criteria used are related to indoor air quality, thermal comfort, energy consumption and stability of control strategies. The results show that the low pressure ventilation system can improve the indoor air quality and reduce the fan energy consumption compared to the reference system while maintaining the same building energy consumption for heating.     

Energy retrofit of commercial buildings: case study and applied methodology

Commercial buildings are responsible for a significant share of the energy requirements of European Union countries. Related consumptions due to heating, cooling, and lighting appear, in most cases, very high and expensive. Since the real estate is renewed with a very small percentage each year and current trends suggest reusing the old structures, strategies for improving energy efficiency and sustainability should focus not only on new buildings, but also and especially on existing ones. Architectural renovation of existing buildings could provide an opportunity to enhance their energy efficiency, by working on the improvement of envelopes and energy supply systems. It has also to be noted that the measures aimed to improve the energy performance of buildings should pay particular attention to the cost-effectiveness of the interventions. In general, there is a lack of well-established methods for retrofitting, but if a case study achieves effective results, the adopted strategies and methodologies can be successfully replicated for similar kinds of buildings. In this paper, an iterative methodology for energy retrofit of commercial buildings is presented, together with a specific application on an existing office building. The case study is particularly significant as it is placed in an urban climatic context characterized by cold winters and hot summers; consequently, HVAC energy consumption is considerable throughout the year. The analysis and simulations of energy performance before and after the intervention, along with measured data on real energy performance, demonstrate the validity of the applied approach. The specifically developed design and refurbishment methodology, presented in this work, could be also assumed as a reference in similar operations.     

Uncertainties in energy and economic performance of HVAC systems and energy recovery ventilators due to uncertainties in building and HVAC parameters

Energy recovery ventilators (ERVs) are exhaust air energy recovery devices for outdoor ventilation air preconditioning in building HVAC systems. The energy and economic performance of an ERV depends on its effectiveness, cost, maintenance as well as other parameters such as climate, building design and HVAC system parameters. In this study, a sensitivity analysis is used to evaluate the impact of uncertainty of building and HVAC system parameters on the energy savings potential and economics of ERVs. Firstly, the impact of building parameters on HVAC system peak loads, capital cost, annual energy use and operating cost are investigated for an office building located in Chicago using TRNSYS simulations. The results show that the ventilation rate has the most significant impact on total HVAC system energy performance. Secondly, energy and economic analysis on the ERV’s payback period is conducted with a specified variation of each input parameter. The results illustrate that an ERV with 75% sensible and 60% latent effectiveness can reduce the peak heating load by 30%, the peak cooling load by 18%, the annual heating energy usage by 40% and the annual cooling energy usage by 8%, with a payback period of 2 years. The uncertainty of ERV’s payback period to its initial cost, recovery effectiveness, energy rate, HVAC equipment initial cost and efficiency as well as ventilation rate are also presented. A ±25% uncertainty in the 7 building and HVAC system input parameters studied results in a maximum 17% and 225% uncertainty in the payback period of the ERV respectively.     

DAYLIGHTING TECHNOLOGIES IN NON-DOMESTIC BUILDINGS

Natural daylight is an inexpensive and very efficient light source provided that the amount of daylight entering a building is controlled according to demand. In commercial buildings electricity for lighting can be cut by 50-75% using daylighting design techniques in combination with efficient artificial lighting. New lighting control technologies and advanced computer simulation tools lo optimize large buildings makes it possible to exploit these energy savings.

Daylight is a very efficient light source, providing more light for less input of thermal energy than any other artificial light source. Efficient shading systems are now emerging systems that can control the admission of daylight to the room according to requirement, and avoid overheating. Some of these systems, such as reflective light shelves, will also contribute to a better distribution of the daylight available by redistributing some daylight to the back of the room. However, more work is needed to develop and test such combined daylight and shading systems.

The use of daylight to reduce electric lighting must be seen as an integrated part of the overall energy optimization of the building. An efficient control of the use of daylight and artificial lighting will not only reduce electricity use for lighting. Additionally, the use of electricity for ventilation and cooling can be reduced also, because the internal heat gains provocating these electricity uses are reduced. This calls for an integrated design approach to the overall energy design of the building, involving the architect and the engineer from the very beginning of the design phase.

Visual comfort of office buildings receives increasing attention, partially because of the VDU's (Visual Display Units) of the computers, that are now almost standard equipment of every work place. The performance requirements for both daylighting systems and artificial lighting systems have been sharpened, and the attention to this fact is crucial in future development of lighting systems.     

Energy savings versus costs of implementation for demand side management strategies within an energy-efficient tropical residence

As renewable energy sources and net-zero energy homes become increasingly pervasive within the residential building industry, further reductions in consumption patterns will occur through demand side management (DSM). DSM can include measures such as energy-efficient system design, automated control and energy management systems, or policies and monitoring systems intended to alter user behavior. For an energy-efficient modern residence designed within a tropical context, several DSM strategies are considered for reductions in operational-phase energy consumption: a lightweight, thermally high-performing building envelope, installation of light dimmers to enhance user control of lighting, and comparison of a solar hot water system versus a point-of-use electric water heater to produce hot water for bathing demands. The energy-consumption savings associated with the three DSM strategies are simulated and normalized to an energy savings per cost of implementation basis in kWh per 1000 Thai Baht (THB) for comparison. The results show that financial investments in low-energy hot water heaters (i.e., solar water heating systems) result in relatively higher energy savings per unit financial investment than the other two strategies. Conversely, the installation of a lightweight, well-insulated envelope is highly expensive relative to its associated energy savings over a 25-year time frame. The savings associated with the insulated envelope, light dimmers, and hot water production strategies are evaluated at 80, 609 and 657 kWh/1000 THB investment, respectively.     

A cost‐effective operating strategy to reduce energy consumption in a HVAC system

The operation of the building heating, ventilating, and air conditioning (HVAC) system is a critical activity in terms of optimizing the building's energy consumption, ensuring the occupants' comfort, and preserving air quality. The performance of HVAC systems can be improved through optimized supervisory control strategies. Set points can be adjusted by the optimized supervisor to improve the operating efficiency. This paper presents a cost‐effective building operating strategy to reduce energy costs associated with the operation of the HVAC system. The strategy determines the set points of local‐loop controllers used in a multi‐zone HVAC system. The controller set points include the supply air temperature, the supply duct static pressure, and the chilled water supply temperature. The variation of zone air temperatures around the set point is also considered. The strategy provides proper set points to controllers for minimum energy use while maintaining the required thermal comfort. The proposed technology is computationally simple and suitable for online implementation; it requires access to some data that are already measured and therefore available in most existing building energy management and control systems. The strategy is evaluated for a case study in an existing variable air volume system. The results show that the proposed strategy may be an excellent means of reducing utility costs associated with maintaining or improving indoor environmental conditions. It may reduce energy consumption by about 11% when compared with the actual strategy applied on the investigated existing system. Copyright © 2007 John Wiley & Sons, Ltd.     

Evaluation of electrochromic windows impact in the energy performance of buildings in Mediterranean climates

Old buildings refurbishment is essential for the global improvement of building energy indicators. Within this context, the paper focuses on the energy savings that may occur when using electrochromic (EC) windows, an interesting emerging technology alternative to shading devices to control solar gain in buildings located in Mediterranean climates. The EC windows technology is briefly presented and the optical properties adjustments of the glasses are discussed according to the operated range. The EC window dynamic behavior and the different control strategies are modeled and implemented in the ESP-r building simulation program. The EC window impact in the energy needs for heating and cooling is studied, considering different ambient parameters (exterior dry bulb temperature, interior dry bulb temperature and incident radiation) and set points for the EC control. A comparison of several windows solutions (single, double-glazing and EC windows), the type of building, internal gains from occupancy, lighting and equipment and the orientation of windows are considered for discussion through the analysis of the energy needs for heating and cooling. It is concluded that for this climate the best positive results are obtained when the EC are used in the west façade. For the south façade the results show no significant advantages in using EC windows.     

Mixed-mode ventilation and air conditioning as alternative for energy savings: a case study in Beirut current and future climate

The aim of this work is to assess the use of mixed-mode ventilation for a typical office building in Lebanon and consequently reduce Heating Ventilation and Air Conditioning (HVAC) energy consumption in the observed current and under the future projected climatic conditions. Mixed-mode cooling is considered a compromise between the insufficient natural ventilation and the expensive year round-operated HVAC. A control algorithm is set for windows and HVAC system to ensure mixed-mode operation. Dynamic simulations are performed on a typical office building in Beirut City under the mixed-mode operation in the present and the future using commercial IES-VE software. The results of the software were validated against measured HVAC and total energy consumption of the typical office base case with conventional mechanical system. The results of the simulations are evaluated in terms of potential reduction in energy consumption under the present and the future weather data. Finally, a lifecycle cost analysis is performed for the proposed system, and its payback period is computed. Under present construction practices and weather data, 31% annual energy savings were achieved using mixed-mode system. Under future 2050s projected weather data, annual energy savings of 21% was attained with a payback period of 3.8 years.     

A generalized window energy rating system for typical office buildings

Detailed computer simulation programs require lengthy inputs, and cannot directly provide an insight to relationship between the window energy performance and the key window design parameters. Hence, several window energy rating systems (WERS) for residential houses and small buildings have been developed in different countries. Many studies showed that utilization of daylight through elaborate design and operation of windows leads to significant energy savings in both cooling and lighting in office buildings. However, the current WERSs do not consider daylighting effect, while most of daylighting analyses do not take into account the influence of convective and infiltration heat gains. Therefore, a generalized WERS for typical office buildings has been presented, which takes all primary influence factors into account. The model includes embodied and operation energy uses and savings by a window to fully reflect interactions among the influence parameters. Reference locations selected for artificial lighting and glare control in the current common simulation practice may cause uncompromised conflicts, which could result in over- or under-estimated energy performance. Widely used computer programs, DOE2 and ADELINE, for hourly daylighting and cooling simulations have their own weaknesses, which may result in unrealistic or inaccurate results. An approach is also presented for taking the advantages of the both programs and avoiding their weaknesses. The model and approach have been applied to a typical office building of Hong Kong as an example to demonstrate how a WERS in a particular location can be established and how well the model can work. The energy effect of window properties, window-to-wall ratio (WWR), building orientation and lighting control strategies have been analyzed, and can be indicated by the localized WERS. An application example also demonstrates that the algebraic WERS derived from simulation results can be easily used for the optimal design of windows in buildings similar to the typical buildings.     

Verification of electrical energy savings for lighting retrofits using short- and long-term monitoring

This paper presents the verification of the annual electrical energy savings associated with lighting retrofits using short- and long-term monitoring. The effort was part of a US utility-sponsored energy efficiency program to reduce energy consumption in commercial and industrial facilities. Although this paper describes the verification procedures in three facilities, the recommended methods have broad application. In this study, we first conducted lighting energy audits to identify lighting efficiency measures at three facilities, namely an office building, an industrial manufacturing plant, and a city hospital. Then, we estimated the lighting energy savings for the facilities and sought to present the results in a meaningful form. Actual energy savings were measured using short- and long-term monitoring. In all cases, the energy savings measured were within 30% of the projected energy savings.     

Measurements of solar radiation and illuminance on vertical surfaces and daylighting implications

There is a growing concern about the rapid development of infrastructure and building projects and their likely impacts on the environment. Particular concerns have been raised about office building developments and energy consumption issues. In recent years, there has been increasing interest in using daylight to save energy in buildings. Lighting control integrated with daylighting is recognised as an important and useful strategy in terms of energy-efficient building design. It is believed that proper daylighting schemes can help reduce the electrical demand and contribute to achieving environmentally sustainable building developments. This paper presents a simple method for estimating the likely energy savings in electric lighting due to daylighting and the possible cooling penalty. Vertical solar radiation and illuminance data measurements are described. Cumulative frequency distributions of daylight availability are reported. The likely energy savings in office buildings are determined based on on–off and top-up controls, and the energy and environmental implications are discussed.     

Reducing energy use in the buildings sector: measures, costs, and examples

This paper reviews the literature concerning the energy savings that can be achieved through optimized building shape and form, improved building envelopes, improved efficiencies of individual energy-using devices, alternative energy using systems in buildings, and through enlightened occupant behavior and operation of building systems. Cost information is also provided. Both new buildings and retrofits are discussed. Energy-relevant characteristics of the building envelope include window-to-wall ratios, insulation levels of the walls and roof, thermal resistance and solar heat gain coefficient of windows, degree of air tightness to prevent unwanted exchange of air between the inside and outside, and presence or absence of operable windows that connect to pathways for passive ventilation. Provision of a high-performance envelope is the single most important factor in the design of low-energy buildings, not only because it reduces the heating and cooling loads that the mechanical system must satisfy but also because it permits alternative (and low-energy) systems for meeting the reduced loads. In many cases, equipment with significantly greater efficiency than is currently used is available. However, the savings available through better and alternative energy-using systems (such as alternative heating, ventilation, cooling, and lighting systems) are generally much larger than the savings that can be achieved by using more efficient devices (such as boilers, fans, chillers, and lamps). Because improved building envelopes and improved building systems reduce the need for mechanical heating and cooling equipment, buildings with dramatically lower energy use (50–75% savings) often entail no greater construction cost than conventional design while yielding significant annual energy-cost savings.