Benefits and costs of improved IEQ in U.S. offices

This study estimates some of the benefits and costs of implementing scenarios that improve indoor environmental quality (IEQ) in the stock of U.S. office buildings. The scenarios include increasing ventilation rates when they are below 10 or 15 l/s per person, adding outdoor air economizers and controls when absent, eliminating winter indoor temperatures >23°C, and reducing dampness and mold problems. The estimated benefits of the scenarios analyzed are substantial in magnitude, including increased work performance, reduced Sick Building Syndrome symptoms, reduced absence, and improved thermal comfort for millions of office workers. The combined potential annual economic benefit of a set of nonoverlapping scenarios is approximately $20 billion. While the quantitative estimates have a high uncertainty, the opportunity for substantial benefits is clear. Some IEQ improvement measures will save energy while improving health or productivity, and implementing these measures should be the highest priority. PRACTICAL IMPLICATIONS: Owners, designers, and operators of office buildings have an opportunity to improve IEQ, health, work performance, and comfort of building occupants and to obtain economic benefits by improving IEQ. These benefits can be achieved with simultaneous energy savings or with only small increases in energy costs.     

Air flow rates and energy saving potential in schools with demand-controlled displacement ventilation

Demand control is particularly energy efficient and reliable when combined with displacement ventilation (DCDV). In order to investigate how much DCDV in practice reduce the ventilation air volumes and the energy demand, two Norwegian schools with CO₂-sensor based demand controlled displacement ventilation (DCDV-CO₂), Jaer School and Mediå School, are analysed and compared with traditional constant air volume (CAV) mixing ventilation. During daytime operation with normal school activity, DCDV-CO₂ reduces the ventilation air volume by 65–75% in both schools compared to CAV. For Mediå School, both the airflow rates and the energy performance were analysed through measurements and use of a detailed, calibrated simulation model. The analysis period was 11–17 November, 2002. It was found that during this week, DCDV-CO₂ daytime operation weekdays reduce the total heating energy demand by 21%, the amount of unrecovered heat in the exhaust ventilation air by 54%, and the average airflow rate by 50%. Presuming constant fan efficiency it was also found that DCDV-CO₂ daytime operation weekdays reduce the fan energy consumption by 87% the analysed week.     

An energy impact assessment of ventilation for indoor airborne bacteria exposure risk in air-conditioned offices

Treatment of fresh air in ventilation systems for air-conditioned offices consumes a significant amount of energy and affects the indoor air quality (IAQ). In this study, energy impact on the ventilation systems was examined against certain IAQ objectives for indoor airborne bacteria exposure risk in air-conditioned offices of Hong Kong. The relationship between thermal energy consumptions and indoor airborne bacteria exposure levels based on regional surveys was investigated. The thermal energy consumptions of ventilation systems operating for carbon dioxide (CO₂) exposure concentrations between 800 and 1200 ppmv for typical office buildings and the corresponding failure probability against some target bacteria exposure levels were evaluated. The results showed that, for a reference indoor environment at a CO₂ exposure concentration of 1000 ppmv, the predicted average thermal energy saving of ventilation system for a unit increment of the expected risk of unsatisfactory IAQ of 1% was 55 MJ m⁻² yr⁻¹ and for a unit decrement of 1%, the predicted additional thermal energy consumption was 58 MJ m⁻² yr⁻¹ respectively. This study would be a useful source of reference in evaluation of the energy performance of ventilation strategies in air-conditioned offices at a quantified exposure risk of airborne bacteria.     

美国的新型建筑节能墙体材料

各种新型节能建筑材料种类繁多，本文将对几种主要的新型节能墙体材料在美国民用建筑中的应用情况及其发展背景做一分析介绍。     

Estimated effect of ventilation and filtration on chronic health risks in U.S. offices,schools, and retail stores

We assessed the chronic health risks from inhalation exposure to volatile organic compounds (VOCs) and particulate matter (PM2.5) in U.S. offices, schools, grocery, and other retail stores and evaluated how chronic health risks were affected by changes in ventilation rates and air filtration efficiency. Representative concentrations of VOCs and PM2.5 were obtained from available data. Using a mass balance model, changes in exposure to VOCs and PM2.5 were predicted if ventilation rate were to increase or decrease by a factor of two, and if higher efficiency air filters were used. Indoor concentrations were compared to health guidelines to estimate percentage exceedances. The estimated chronic health risks associated with VOC and PM2.5 exposures in these buildings were low relative to the risks from exposures in homes. Chronic health risks were driven primarily by exposures to PM2.5 that were evaluated using disease incidence of mortality, chronic bronchitis, and non‐fatal stroke. The leading cancer risk factor was exposure to formaldehyde. Using disability‐adjusted life years (DALYs) to account for both cancer and non‐cancer effects, results suggest that increasing ventilation alone is ineffective at reducing chronic health burdens. Other strategies, such as pollutant source control and the use of particle filtration, should also be considered.     

南方建筑通风与空调节能潜力研究

以广州气象条件为例,利用特征温度法模拟研究了南方建筑在通风最佳、最差和失控情况下的全年空调耗冷量.研究表明自然通风的节能效果虽然显著,但最大的节能潜力是有限的;如果自然通风失控,后果更为严重──耗冷量的增加可能数倍甚至数十倍于最大节能量.建议对南方地区"做好通风就节能"的观点重新审视;业界包括建筑师和建筑使用者应多方配合,避免因建筑通风而造成能源的巨大浪费.     

改进酒店旧厨房空调换气系统节能潜力分析

实测了某酒店厨房主要位置在不同换气量条件下空气含氧量,CO和CO2体积分数分布及随使用时间的变化,建立了厨房内污染物平均体积分数随换气次数、使用时间、残留率、污染物理论生成量变化的数学模型。实测结果表明,改进旧厨房空调换气系统节能潜力很大。     

Energy saving potential and repercussions on indoor air quality of demand controlled residential ventilation strategies

Ventilation is ambiguously related to the energy saving rationale originating from the mitigation of global warming, the reaching of peak oil or health concerns related to fossil fuel burning. Since it makes up for about half of the energy consumption in well-insulated buildings, it is an attractive target for energy saving measures. However, simply reducing ventilation rates has unwanted repercussions on the indoor air quality. Two main strategies have been developed to reconcile these seemingly opposing interests: heat recovery and demand control ventilation. This paper focuses on the energy saving potential of demand controlled mechanical exhaust ventilation in residences and on the influence such systems may have on the indoor air quality to which the occupants of the dwellings are exposed. The conclusions are based on simulations done with a multi-zone airflow model of a detached house that is statistically representative for the average Belgian dwelling. Four approaches to demand based control are tested and reported. Within the paper exposure to carbon dioxide and to a tracer gas are used as indicators for indoor air quality. Both energy demand and exposures are reported and compared to the results for a standard, building code compliant, exhaust system, operating at continuous flow rates. The sensitivity of the control strategies to environmental and user variations is tested using Monte-Carlo techniques. Under the conditions that were applied, reductions on the ventilation heat loss of 25–60% are found, depending on the chosen control strategy (with the exclusion of adventitious ventilation and infiltration).     

Whole building energy simulation and energy saving potential analysis of a large public building

This article explores how to use EnergyPlus to construct models to accurately simulate complex building systems as well as the inter-relationships among sub-systems such as heating, ventilation and air conditioning (HVAC), lighting and service hot water systems. The energy consumption and cost of a large public building are simulated and calculated for Leadership in Energy and Environmental Design (LEED) certification using EnergyPlus. American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) baseline model is constructed according to ASHRAE 90.1 standard and the comparison of annual energy consumption between ASHRAE baseline model and proposed model is carried out. Moreover, an energy efficiency (EE) model is built based on the design model. Meanwhile, other energy conservation measures (ECMs) such as daylighting dimming and occupant sensors are considered. The simulation results show 4.7% electricity consumption decrease but 6.9% gas consumption increase of the EE model compared to ASHRAE baseline model. In summary, the annual energy cost of the EE model is reduced by 7.75%.     

自然通风与节能舒适性分析

介绍了自然通风技术的基本原理与应用形式,从建筑物节能与舒适性两方面探讨了自然通风在建筑物中的应用,指出在自然通风的设计和应用过程中应综合考虑地理气候、建筑物结构和环境调节要求等因素,同时应加强相关技术的研究和开发。     

北京市大型公共建筑用能现状与节能潜力分析

介绍了北京市大型公共建筑的数量、建筑面积、总体用能情况，根据能耗现场实测数据讨论了宾馆、商场、写字楼三类建筑的用能特点，分析了大型公共建筑的节能潜力，认为综合利用各类建筑节能技术，大型公共建筑可以节能30％-50％。     

Rice milling industry in India: energy saving potential of energy efficient motors

A somewhat generalised framework for estimating the energy savings potential of energy efficient motors in the rice milling industry in India has been proposed. Relationship between the paddy processing capacity of the rice mill and its power rating has been developed from the available data. For realistic estimation of power rating, new factors have been proposed. Regression curves of motor efficiency on its power rating have also been developed for both standard and energy efficient motors. Based on these relationships, the energy savings potential for various cases has been estimated. Finally, the financial feasibility of using energy efficient motors in place of standard motors in rice milling industries has been evaluated.     

北方旅客站房候车大厅通风降温策略及节能分析

在北方地区通风降温分区及自然通风热舒适评价基础上,选择分区内典型城市气象参数,利用EnergyPlus软件,对旅客站房自然通风、机械通风、太阳能强化通风及蒸发冷却的通风降温效果及能耗进行了研究。结果表明:对于Ⅰ区,采用机械通风及其他强化通风措施能有效减少室内高温时间,累计高温天数小于5d,该地区候车室可以取消空调系统;对于Ⅱ区,机械通风能有效降低室内高温时间,与空调系统相比,节能率约为35.8%;对于Ⅲ区,蒸发冷却空调系统是一种很好的通风降温方式,采用二级蒸发冷却空调系统与一级泵变流量空调系统相比,节能率约为38.9%;对于Ⅳ区,空调应为主要的降温手段,但要考虑全新风和夜间通风运行模式,以最大限度地利用自然资源,降低空调能耗。     

通风与空调系统节能性能现场检测方法及节能性能分析

本文介绍了通风与空调系统节能性能检测的目的及具体方法,从而引申出通风与空调系统节能检测对建筑节能的重要性并对其节能检测进行探讨。     

Alternative regional specification and convergence of U.S. regional growth rates

We apply absolute beta convergence techniques to cross sectional per capita income data for alternative specifications of U.S. regions in order to detect whether U.S. regional growth rates are converging over relatively recent time periods. We also explore whether estimates of convergence differ between economic and political region specifications. We show that convergence of growth rates across regions of the U.S. has continued in modern times (1969–1997) for almost any regional specification and for all time frames considered. We do find, however, some difference in convergence rates between economic and political regions. Convergence coefficients, however, are remarkably similar across alternative economic region specifications. An earlier version of this paper was presented in February 2003 at the 42nd annual meetings of the Western Regional Science Association in Rio Rico, Arizona. We would like to thank our session participants in Rio Rico and three anonymous referees for helpful comments. Any remaining errors or oversights, however, are entirely our responsibility.     

混凝土多排孔砌块 粘土多孔砖节能建筑综合经济分析

介绍按苏北典型气候,分别应用混凝土多排孔砌块和ＫＰ１粘土多孔砖建筑的试点节能住宅,并从经济技术和功能价值方面进行综合对比,得出最优设计方案。     

Energy saving potential and strategies for electric lighting in future North European, low energy office buildings: A literature review

This article presents key energy use figures and explores the energy saving potential for electric lighting in office buildings based on a review of relevant literature, with special emphasis on a North European context. The review reveals that theoretical calculations, measurements in full-scale rooms and simulations with validated lighting programs indicate that an energy intensity of around 10 kWh/m² yr is a realistic target for office electric lighting in future low energy office buildings. This target would yield a significant reduction in energy intensity of at least 50% compared to the actual average electricity use for lighting (21 kWh/m² yr in Sweden). Strategies for reducing energy use for electric lighting are presented and discussed, which include: improvements in lamp, ballast and luminaire technology, use of task/ambient lighting, improvement in maintenance and utilization factor, reduction of maintained illuminance levels and total switch-on time, use of manual dimming and switch-off occupancy sensors. Strategies based on daylight harvesting are also presented and the relevant design aspects such as effects of window characteristics, properties of shading devices, reflectance of inner surfaces, ceiling and partition height are discussed.     

Energy analysis for workshops with floor–supply displacement ventilation under the U.S. climates

Many studies have shown that floor–supply displacement ventilation systems are better than mixing ventilation systems. The benefits include indoor air quality, thermal comfort and reduced energy use. The energy benefits depend on the climate conditions. This research compared the energy use of a floor–supply displacement ventilation system in a large industrial workshop with that of a mixing ventilation system for five U.S. climate regions. It was found that the energy use and the system performance vary with the locations. The displacement ventilation system may use more fan and boiler energy but less chiller energy than the mixing ventilation system. The total energy used is slightly less with displacement ventilation, although the ventilation rate was increased in order to handle the high cooling loads found in U.S. buildings. Thus, the displacement ventilation system can save some energy in cooling mode. However, displacement ventilation system has a lower capacity of dehumidification. This system alone, thus, is not suggested for use in humid regions.     

光伏建筑一体化建筑空调负荷特点及节能对策分析

认为光伏建筑一体化和并网发电将是人口密集的城市利用太阳能的主要形式。分析了光伏一体化建筑中光伏器件对空调系统的影响、此类建筑空调负荷的特点及计算方法问题,从复合能量系统的角度提出了有利于空调通风系统节能发展的新策略。