Lighting energy savings in offices using different control systems and their real consumption

This paper compares the potential of lighting energy savings in office rooms by using different control systems, for three locations in Europe and the four main orientations. The method is based on DAYSIM simulations to perform daylight calculations, on laboratory measurement to evaluate precise system energy consumptions and on the implementation of a new algorithm to simulate a close-loop daylight dimming system. It appears that the control of the electrical power in function of daylight leads to very high savings; they slightly depend on the room orientation and the location. Savings vary from 45 to 61%. The performances of an occupancy sensor are also tested. Threshold values of occupancy rate for which daylight dimming leads to higher gains than an occupancy control system vary between 27 and 44% depending on location and orientation. The measurements of the energy consumption of the sensors and detectors also permit to conclude that systems with embedded DALI-compatible ballast controllers should be abandoned in favour of a centralized DALI-compatible ballast controller or embedded analogue systems.     

Experimental study of using PCM in brick constructive solutions for passive cooling

This work presents the results of an experimental set-up to test phase change materials with two typical construction materials (conventional and alveolar brick) for Mediterranean construction in real conditions. Several cubicles were constructed and their thermal performance throughout the time was measured. For each construction material, macroencapsulated PCM is added in one cubicle (RT-27 and SP-25 A8). The cubicles have a domestic heat pump as a cooling system and the energy consumption is registered to determine the energy savings achieved. The free-floating experiments show that the PCM can reduce the peak temperatures up to 1 °C and smooth out the daily fluctuations. Moreover, in summer 2008 the electrical energy consumption was reduced in the PCM cubicles about 15%. These energy savings resulted in a reduction of the CO₂ emissions about 1-1.5 kg/year/m².     

The use of a double heat pipe heat exchanger system for reducing energy consumption of treating ventilation air in an operating theatre—A full year energy consumption model simulation

In two earlier papers [Y.H. Yau, Application of a heat pipe heat exchanger to dehumidification enhancement in tropical HVAC systems—a baseline performance characteristics study, International Journal of Thermal Sciences 46 (2) (2007) 164–171; Y.H. Yau, The analysis of enthalpy change with and without a heat pipe heat exchanger in a tropical air conditioning system, International Journal of Energy Research 30 (15) (2006) 1251–1263], two series of experiments were conducted under controlled conditions to establish the baseline performance characteristics of the heat pipe heat exchanger (HPHX). In the present paper, a complete empirical transient systems simulation program model is assembled to estimate the air states as well as the entire typical meteorological year energy consumption of an operating theatre located in Kuala Lumpur, Malaysia.     

区域供冷系统能耗分析

针对区域供冷系统存在的能耗问题,通过对日本两个典型区域供冷项目具体案例的深入分析,指出其能耗水平,结合国内典型公共建筑分散供冷供暖系统的能耗数据,指出区域供冷高能耗的根源所在.在分析了国外一些成功区域供冷案例的成功之处后,进一步指出区域供冷遇到的各种问题,认为区域供冷系统节能的前提条件是具备高密度的冷负荷用户和足够量的廉价天然冷源.     

Savings on natural gas consumption by doubling thermal efficiencies of balanced-flue space heaters

Natural gas is a relatively clean fossil fuel for space heating. However, when it is not used efficiently high consumption can become an environmental problem. In Argentina, individual balanced-flue space heaters are the most extensively used in temperate and cold regions. This furnace is a simple device with a burner set into a metal chamber, separated from the indoor ambient by an enclosing cabinet, and both inlet and outgas chimneys are connected to the outdoor ambient. In previous studies, we measured the performance of these commercial devices, and found very low thermal efficiency (in the range of 39–63% depending on the chimney configuration). The extensive use of these devices is possible due to the availability of unlimited amount of subsidised natural gas to households and businesses. In the present work, we developed a prototype with simple and low cost modifications made on commercial models, and measured the improvements on the thermal efficiency. Findings showed better infrared radiation, enhanced indoor air convection, and passive chimney flow regulation leading to thermal efficiency in the range of 75–85%. These values represent an improvement of 100% when compared to marketed models, and hence, the specific cost of the heater per unit of useful heating power delivered was actually reduced. Considering the large market presence of these furnaces in both residential and business sectors in Argentina, the potential benefits related to gas consumption and environmental emissions are very significant.     

Evaluation of distributed environmental control systems for improving IAQ and reducing energy consumption in office buildings

Conventional heating, ventilation, and air conditioning (HVAC) systems are incapable of providing control over individual environments or adjusting fresh air supply based on the dynamic occupancy of individual rooms in an office building. This paper introduces the concept of distributed environmental control systems (DECS) and shows that improvement in indoor air quality (IAQ) and energy efficiency can be achieved by providing required amounts of fresh air directly to the individual office spaces through distributed demand controlled ventilation (DDCV). In DDCV, fresh air is provided to each micro-environment (room or cubicle) based on input from distributed sensors (CO₂, VOC, occupancy, etc.) or intelligent scheduling techniques to provide acceptable IAQ for each occupant, rather than for groups or populations of occupants. In order to study DECS, a numerical model was developed that incorporates some of the best available models for studying building energy consumption, indoor air flow, contaminant transport and HVAC system performance. The developed model was applied to a DECS in a model office building equipped with a DDCV system. By implementing DECS/DDCV and intelligent scheduling techniques it is possible to achieve an improvement in IAQ along with a reduction in annual energy consumption compared to conventional ventilation systems.     

Reducing energy peak consumption with passive climate control methods

In recent years, European electrical consumption in buildings is experiencing a marked increase, rising to values above design conditions. Consequently, power cuts occur in different periods, such as during the early morning hours in winter and the last hours of occupation in summer. To solve this problem, passive methods could help to reduce energy peaks. Specifically, internal wall coverings were applied to define the moisture-buffering capacity of permeable coverings in indoor air. These permeable coverings improved the indoor partial vapour pressure and, as a result, the ambience acceptability and local thermal comfort, despite the use of an air barrier and less permeable coverings, when compared with other authors. The daily periods in which internal coverings work are clearly defined, and give us an understanding of the peak energy consumption at different times. In particular, peak reductions of 20% and 4% in the energy consumption for indoor air conditioning, respectively during the summer and winter seasons, were obtained with permeable coverings. Permeable coverings have been demonstrated to be an effective solution as a passive control method for indoor air conditions, especially in the summer season and, consequently, are an energy saving technique.     

Experimental investigation of an innovative low electricity consumption air cooling system for small building application

This paper investigates the development of a low cost air cooling system used for small scale applications. Its operation is based on the rational and efficient use of energy available in conventional freezers, used for other purposes than air conditioning, to cool small areas. In this paper, the proposed air cooling system is applied to small kiosk prototype (called “periptero”), found very often in the streets of Greek cities and villages, used to sell goods to people. The proposed air cooling system is using the low temperature air inside the freezers to cool the air inside the kiosk and provide a better living environment for the owner, particularly during summer period. The basic principle of the system operation and the experimental installation will be described and the experimental results will be presented and discussed.     

A method for heating consumption assessment in existing buildings: A field survey concerning 120 Italian schools

A field survey was carried out in order to collect, elaborate and analyse data concerning the actual energy consumption for space heating of a sample of about 140 buildings (120 high schools) in the Province of Torino (Italy).     

Energy consumption criteria and labeling program of wet cooling towers in Iran

Increasing concerns about the lack of energy resources, global warming and environmental pollution have pushed the relevant organizations to develop energy saving strategies such as energy labeling programs. In this research, a new energy labeling program is developed and evaluated for the wet cooling towers in Iran. The cooling tower parameters, including its cooling capacity and the fan power consumption, are measured using an experimental setup. The experimental data are standardized to compensate the effect of the ambient wet bulb temperature on the cooling tower performance which cannot be controlled during the experiments. The results show that the cooling tower capacity and the fan power consumption may be correlated properly using a linear function which conducts the authors to present a linear energy index (EI). Based on the statistical analysis of a comprehensive range of products, the energy rating limits are extracted for the main types of cooling towers, including induced draft and forced draft ones. The economical and environmental impression of the program authorization is also discussed in detail. Administration of such program may lead to considerable energy saving in the cooling systems which have major economical and environmental benefits, especially in the large industries.     

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

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

Quantifying energy savings in daylight responsive systems: The role of dimming electronic ballasts

The application of lighting control technologies with photosensors has led to an increase in public interest. Although these technologies have been promoted during the last years their successful use in buildings has been accomplished in a small percentage of new projects. One reason is the difficulty in quantifying the energy savings and thus the subsequent payback period. Daylight responsive dimming systems consist of three basic components: photosensor, controller, and dimming unit. Electronic dimming ballast (EDB) is one substantial component of these lighting control systems which can adjust the light output due to the transferred signal from the photosensor and lighting controller. The aim of this study is to quantify energy savings among different EDBs. Eighteen commercial EDBs were selected and various sets of electrical and illuminance measurements were taken for different dimming levels, in order to develop polynomial functions between light output and consumed power. Using the measured data, a set of simulations were performed for a photosensor with an ideal cosine spatial sensitivity distribution installed in a typical office room using two control algorithms, closed loop and integral reset, trying to quantify the relative differences in energy savings.     

Analysis and modelling of window and glazing systems energy performance for a well insulated residential building

The energy performance of a window depends on its thermal transmittance, the glazing solar transmittance, and the air leakage due to the frame and installation airtightness.In new installations air leakage represents a quite small term which is almost independent from the window and in particular from the glazing system selection.The contributions of the two other terms to the building thermal balance are not independent to each other: the most effective thermal insulating glazing, as triple glazings, are generally characterized by low solar transmittance reducing solar gains. The thermal energy balance of the building is then affected not only in summer but also in winter, potentially increasing heating energy need.This work evaluates the impact of different kinds of glazing systems (two double and two triple glazings), window size (from 16% to 41% of window to floor area ratio), orientation of the main windowed façade and internal gains on winter and summer energy need and peak loads of a well insulated residential building. The climatic data of four localities of central and southern Europe have been considered: Paris, Milan, Nice and Rome. A statistical analysis has been performed on the results in order to identify the most influencing parameters.     

动力分散系统的输送能耗分析

对6种形式的动力分散系统的输送能耗进行了计算分析.结果表明,在设计工况下,动力分散系统相对于动力集中系统,输送能耗可以减少31.91%;在80%负荷的调节工况下,动力分散系统相对于采用水泵变速调节的动力集中系统,输送能耗也可以减少31.91%.     

冷热电联供系统成本分摊法研究

根据以微型燃气轮机为动力源的冷热电联供系统的工作流程,建立了其热力学模型.通过对其能量利用过程的分析,引入可用(火用)和折合炯的概念.在综合考虑冷热电联供系统中制冷量和供热量占系统总可用能比例的基础上,建立了以折合(火用)概念为基础的冷热电分摊模型.该模型克服了现有其他方法存在的缺陷,较其他方法更合理、实用.     

Improvement of thermal environment and reduction of energy consumption for cooling and heating by retrofitting windows

Various techniques for creating a comfortable thermal environment and saving energy have been proposed and employed in residential buildings in many countries, including Japan. For these techniques to be introduced, existing houses should be renovated. Among the techniques available, installation of additional inner windows is effective in creating a comfortable and energy-efficient living environment. In the present research, the effect of additional inner windows on the thermal environment and energy saving was investigated by measuring indoor windows on the thermal environment and energy saving was investigated by measuring indoor concrete building. Air temperatures, the humidity, the global solar radiation on horizontal and vertical surfaces, radiant temperatures, and the electricity consumption of air-conditioners were measured. A comparison of these values before and after the installation of inner windows showed that the thermal environment and energy saving had improved. Results obtained from a thermal model agreed well with measured results by changing the value of solar transmittance and heat transmission coefficient of the glazing following renovation. Furthermore, in a questionnaire survey conducted in summer, more than half of the occupants answered ‘‘comfortable’’ to a question on the overall thermal comfort.     

Reducing peak requirements for cooling by using thermally activated building systems

This paper presents general guidelines for the required cooling capacity of an entire office building using thermally activated building systems (TABS). By activating the thermal mass of the building using pipes embedded in the floor, peak loads can be reduced. On-site measurements were performed to obtain the required cooling power of an entire building as well as individual zones. Beside this, the internal climate conditions of rooms and surface temperatures of the TABS were measured. The measured data were used to analyze the predictive performance of a simulation model. In order to acquire general guidelines for the required cooling capacity of a standard office building, simulations of an entire building were used to determine the impact of variable internal heat gains and different sized windows. The required cooling capacity was compared to the cooling capacity of a system without energy buffering (e.g. chilled ceiling panels). It was found that reductions up to 50% of the cooling capacity for a chiller can be achieved using TABS. The presented results within this paper can be used as design guidelines in the first stage of a design process. The results focus on temperate climates and were derived using Dutch climate conditions.     

热电冷联产系统节能性的[火用]分析

利用[火用]分析的方法，定义了等效发电[火用]效率，对常用热电冷联产系统形式的节能性进行了分析。认为相对于全国平均供电煤耗而言，热电冷联产系统的节能是有条件的，应选取合理的方式，优化设计和运行方案；相对于当前有些热电厂夏季负荷不足的情况，热电冷联产是节能的，在不同的情况下节能率在7．8％～39％之间。建议利用现有的热电联产条件，发展热电冷联产系统，提高现有热电厂的设备利用率和运行经济性。     

Modelling electricity consumption in office buildings: An agent based approach

In this paper, we develop an agent-based model which integrates four important elements, i.e. organisational energy management policies/regulations, energy management technologies, electric appliances and equipment, and human behaviour, to simulate the electricity consumption in office buildings. Based on a case study, we use this model to test the effectiveness of different electricity management strategies, and solve practical office electricity consumption problems. This paper theoretically contributes to an integration of the four elements involved in the complex organisational issue of office electricity consumption, and practically contributes to an application of an agent-based approach for office building electricity consumption study.     

热电冷联产系统节能性的(火用)分析

利用分析的方法,定义了等效发电效率,对常用热电冷联产系统形式的节能性进行了分析。认为相对于全国平均供电煤耗而言,热电冷联产系统的节能是有条件的,应选取合理的方式,优化设计和运行方案;相对于当前有些热电厂夏季负荷不足的情况,热电冷联产是节能的,在不同的情况下节能率在7.8%~39%之间。建议利用现有的热电联产条件,发展热电冷联产系统,提高现有热电厂的设备利用率和运行经济性。