Reduce Building Energy Use Research Articles

Consideration of Envelope Airtightness in Modelling Commercial Building Energy Consumption

As strategies for improving building envelope and HVAC equipment efficiencies are increasingly required to reduce building energy use, a greater percentage of energy loss will occur through building envelope leakage. Although the energy impacts of unintended infiltration on a building’s energy use can be significant, current energy simulation software and design methods are generally not able to accurately account for envelope infiltration and the impacts of improved airtightness. The airflow analyses capabilities of several energy simulation software tools are summarized, including whether the program calculates airflow rates for the user or accepts them as inputs. The bases of these airflow rate estimation approaches are evaluated for their physical soundness and accuracy. A new strategy to more accurately incorporate airflow calculations into energy software is also proposed, which is based on relationships between building infiltration rates calculated using detailed multizone airflow models and building characteristics, weather conditions, and building envelope airtightness.

창호 블라인드와 상변화물질 적용에 의한 냉방 에너지 사용량 절감효과에 대한 검토 연구

This study looks into changing building energy use by application of phase change material (PCM). PCM does not need extra energy for operation and is used for reducing building energy use and, CO2 output by displaying semi-permanent effects after installation. It also is able to avoid the maximum electric power time-zone by inducing a time lag phenomenon of cooling and heating loads with high thermal capacity using latent heat. To verify the efficiency of blinds and PCM, tests about the PCM operation mechanism using air conditioning machinery and nocturnal panel cooling were done. In the test results of the case using PCM installation, a blind angle with machinery air conditioning and nocturnal panel cooling at the same time shows a 22 percent energy saving effect against general space. The test results of each case were compared and analyzed based on the blind and window opening settings. Finally, the energy reduction of existing buildings using PCM application was reviewed based on the final measurement results.

Special Issue of ASME JSEE on Integrated/Sustainable Building Equipment and Systems Notes From Guest Editors

This special issue of JSEE is part of the efforts by the ASME Task Force on Integrated/Sustainable Building Equipment and Systems (ISBES) to identify and evaluate challenges and opportunities for integrating sustainable equipment and systems in individual buildings and within the built environment. Specifically, the ISBES Task Force is primarily interested in fostering new technologies and strategies to enhance building energy efficiency and reduce building energy use. This new approach is proceeding on three different but very important tracks:This first special issue is intended to motivate exchange of innovative ideas, leading-edge concepts, new technologies and devices, ongoing R&D efforts, prototype and demonstration projects, commercialization technologies and projects, and visions of the future related to various tracks of Integrated Sustainable Equipment and Systems for Buildings.Most of the papers selected and further peer-reviewed for this special issue have been presented as part of technical sessions specifically organized during the 2012 ASME International Mechanical Engineering Congress and Exhibition (IMECE-2012). The papers cover all three IBSES tracks including (i) integrating innovative energy efficiency humidification technology into buildings, evaluating the potential of designing high performance buildings in developing countries, and examining the LEED rating system using design and performance data obtained for several US buildings, (ii) assessing the integration of thermo-active foundations and energy storage systems into buildings, and (iii) city-scale analysis of predicting energy demands during extreme heat events as well the environmental impact of large scale integration of PV systems in a coastal community. The selected articles represent worldwide applications of these technologies and leading-edge approaches.It is hoped that this special issue would provide a stepping stone to initiate long-term collaboration between academia, industry, and planners worldwide to solve the challenges inherent for developing integrated and sustainable equipment and systems for the built environment. We hope for the collaborations to be multi and to include expertise in various areas including but not limited to Solar Energy, Energy Efficiency, Hydrogen Energy Technology, Advanced Energy Technologies, Materials, Fluid Mechanics of Buildings, and Architectural designs.

THE EFFECT OF MICROENCAPSULATED PHASE-CHANGE MATERIAL ON THE COMPRESSIVE STRENGTH OF STRUCTURAL CONCRETE

Latent heat energy storage through phase-change materials (PCMs) is one possible strategy to control interior temperatures in buildings, improve thermal comfort, and passively reduce building energy use associated with heating and cooling. While PCMs integrated into building structure elements have been studied since the 1970s, challenges of integrating PCMs into building materials while maintaining their heat storage benefits have limited their application in practice. The recent introduction of microencapsulated phase-change materials provides the energy storage capability of PCMs in micron-scale, chemically-inert capsules that can be easily integrated into composite materials such as gypsum wallboard and concrete. The size and physical properties of microencapsulated PCMs suggest that they will behave similarly to filler materials in concrete. Such filler materials are generally less than 125 μm in diameter and can increase concrete strength when added to a mix. This study uses the compressive strength of hardened concrete mixes with varying amounts of PCM to evaluate the effect of PCM addition on concrete structural integrity.

Framework to Evaluate Energy-Saving Potential from Occupancy Interventions in Typical Commercial Buildings in the United States

AbstractOccupancy-focused interventions to reduce building energy use have been shown to be effective but often result in unsustained energy reductions. In addition, these interventions have rarely...

A comprehensive analysis of the impact of occupancy parameters in energy simulation of office buildings

The commercial building sector has become the focus of many governmental energy reduction initiatives to achieve more sustainable development. Reducing building energy use starts by improving the design of buildings. To this end, energy modeling and simulation tools are used during the design phase to predict energy use and help designers choose and size the different building systems. Large discrepancies are however being observed between predicted and actual building energy performances. In order to determine the sources of errors and improve these predictions, the sensitivity of energy models to different input parameters needs to be evaluated. Studies in literature have extensively evaluated the sensitivity of models to the buildings’ technical design parameters. However, none considered the parameters related to the energy consumption behavior of occupants, leaving their impact on energy modeling unknown. This paper presents a comprehensive sensitivity analysis study performed on the occupancy behavioral parameters of typical office buildings of different size and in different weather zones. Significant sensitivity levels were observed, varying according to both building size and weather conditions. The highest sensitivity was obtained when varying the ‘heating temperature set point’ parameter in small-size buildings located in US weather zone 2 Dry.

Overall energy performance of semi-transparent single-glazed photovoltaic (PV) window for a typical office in Hong Kong

Abstract This paper develops an overall methodology for investigating the thermal and power behaviors of semi-transparent single-glazed photovoltaic window for office buildings in Hong Kong. In order to estimate its overall energy performance, this study is conducted in terms of total heat gain, output power and daylight illuminance. Three simulation models are established, including one-dimensional transient heat transfer model, power generation model and indoor daylight illuminance model. A typical office room reference is chosen as case study, and the weather data from 2003 to 2007 from the Hong Kong Observatory are used as the simulation inputs. By incorporating the simulation results, the overall energy performance can be evaluated in terms of electricity benefits corresponding to five orientations of the studied typical office. The priority of office orientation considering overall energy performance is: south-east, south, east, south-west and west. The findings show that thermal performance is the primary consideration of energy saving in the entire system whereas electricity consumption of artificial lighting is the secondary one. The overall annual electricity benefits are about 900 kWh and 1300 kWh for water-cooled and air-cooled air-conditioning systems respectively. The application of semi-transparent PV glazed window can not only produce clean energy, but also reduce building energy use by reducing the cooling load and electrical lighting requirements, which definitely benefits our environmental and economic aspects.

Buildings don't use energy: people do

Reducing energy use in buildings is a critical component of meeting carbon reduction commitments. There are several ways of accomplishing this goal, each of which emphasizes actions by a different set of stakeholders. This article argues that building users play a critical but poorly understood and often overlooked role in the built environment. In the face of climate change, the article finds purely architectural solutions, such as those proposed by the Architecture 2030 Challenge, to be necessary but not sufficient to achieve climate change mitigation targets. To fully address the task ahead, it argues that architects need to develop their professional expertise to improve buildings and seek ways of integrating user involvement in building performance. Moreover, from a professional standpoint, this paper suggests it may be wise for architects to claim a leadership role in this area before another group of building professionals does.

A review of daylight illuminance determinations and energy implications

Daylighting is recognized as an important element in architecture and a useful strategy in energy-efficient building designs. Daylight gives a sense of cheeriness and brightness that can have a significant positive impact on the people. There is a scope for integrating daylight with electric light to reduce building energy use. The amount of daylight entering a building is mainly through window openings, which create in the indoor environment a more attractive and pleasing atmosphere, in addition to maximise visual access to the pleasant views of the outside world. Determinations of the exterior and interior daylight and lighting energy savings are key issues to demonstrate the benefits based on daylighting designs. This paper provides a review of daylight illuminance determinations and the lighting energy reductions due to daylighting schemes. The study includes daylight measurements, prediction of daylight illuminance under various sky conditions and potential electric lighting energy savings from daylight-linked lighting controls. The article aims at providing building professionals, practitioners and researchers more information and a better understanding of daylight for promoting effective daylighting designs and evaluations.

Evolution of Cool-Roof Standards in the US

Evolution of cool roof standards in the United States submitted to Advances in Building Energy Research, 2007-06-15 Accepted for publication, August 2007. Evolution of cool-roof standards in the United States Hashem Akbari and Ronnen Levinson Heat Island Group Lawrence Berkeley National Laboratory Berkeley, CA 94720 USA H_Akbari@LBL.gov Abstract Roofs that have high solar reflectance and high thermal emittance stay cool in the sun. A roof with lower thermal emittance but exceptionally high solar reflectance can also stay cool in the sun. Substituting a cool roof for a noncool roof decreases cooling-electricity use, cooling-power demand, and cooling-equipment capacity requirements, while slightly increasing heating-energy consumption. Cool roofs can also lower citywide ambient air temperature in summer, slowing ozone formation and increasing human comfort. Provisions for cool roofs in energy-efficiency standards can promote the building- and climate- appropriate use of cool roofing technologies. Cool-roof requirements are designed to reduce building energy use, while energy-neutral cool-roof credits permit the use of less energy-efficient components (e.g., larger windows) in a building that has energy-saving cool roofs. Both types of measures can reduce the life-cycle cost of a building (initial cost plus lifetime energy cost). Since 1999, several widely used building energy-efficiency standards, including ASHRAE 90.1, ASHRAE 90.2, the International Energy Conservation Code, and California’s Title 24 have adopted cool-roof credits or requirements. This paper reviews the technical development of cool- roof provisions in the ASHRAE 90.1, ASHRAE 90.2, and California Title 24 standards, and discusses the treatment of cool roofs in other standards and energy-efficiency programs. The techniques used to develop the ASHRAE and Title 24 cool-roof provisions can be used as models to address cool roofs in building energy-efficiency standards worldwide. Introduction Roofs that have high solar reflectance (high ability to reflect sunlight, spectrum 0.3 – 2.5 µm) and high thermal emittance (high ability to emit thermal radiation, spectrum 4 – 80 µm) stay cool in the sun. The same is true of roofs with lower thermal emittance but exceptionally high solar reflectance. Roofs that stay cool in the sun by minimizing solar absorption and maximizing thermal emission are hereafter denoted “cool roofs.” Benefits of cool roofs Low roof temperatures lessen the flow of heat from the roof into the building, reducing the need for space-cooling electricity in conditioned buildings. Since building heat gain through the roof peaks in mid-to-late afternoon, when summer electricity use is highest, cool roofs can also reduce peak electricity demand. Prior research has indicated that savings are greatest for buildings located in climates with long cooling seasons and short heating seasons, particularly

Evolution of Cool-Roof Standards in the US

Roofs that have high solar reflectance and high thermal emittance stay cool in the sun. A roof with lower thermal emittance but exceptionally high solar reflectance can also stay cool in the sun. Substituting a cool roof for a non-cool roof decreases cooling electricity use, cooling power demand and cooling equipment capacity requirements, while slightly increasing heating energy consumption. Cool roofs can also lower the citywide ambient air temperature in summer, slowing ozone formation and increasing human comfort. Provisions for cool roofs in energy efficiency standards can promote the building and climate-appropriate use of cool roofing technologies. Cool-roof requirements are designed to reduce building energy use, while energy-neutral cool-roof credits permit the use of less energy-efficient components (e.g. larger windows) in a building that has energy-saving cool roofs. Both types of measures can reduce the life-cycle cost of a building (initial cost plus lifetime energy cost). Since 1999, several widely used building energy efficiency standards, including ASHRAE 90.1, ASHRAE 90.2, the International Energy Conservation Code and California's Title 24 have adopted cool-roof credits or requirements. This chapter reviews the technical development of cool-roof provisions in the ASHRAE 90.1, ASHRAE 90.2 and California Title 24 Standards, and discusses the treatment of cool roofs in other standards and energy efficiency programmes. The techniques used to develop the ASHRAE and Title 24 cool-roof provisions can be used as models to address cool roofs in building energy efficiency standards worldwide.

Energy-efficient terrace houses in Sweden: Simulations and measurements

Reducing energy use in buildings is essential to decrease the environmental impact. Outside Gothenburg in Sweden, 20 terrace houses were built according to the passive house standard and completed in 2001. The goal was to show that it is possible to build passive houses in a Scandinavian climate with very low energy use and to normal costs. The houses are the result of a project including research, design, construction, monitoring and evaluation. The passive house standard means that the space heating peak load should not exceed 10 W/m 2 living area in order to use supply air heating. This requires low transmission and ventilation losses and the building envelope is therefore highly insulated and very airtight. A mechanical ventilation system with approximately 80% heat recovery is used. The electric resistance heating in the supply air is 900 W per living unit. Solar collectors on the roof provide 40% of the energy needed for the domestic hot water. The monitored delivered energy demand is 68 kWh/m 2 a. Energy simulations show that main differences between predicted and monitored energy performance concern the household electricity and the space heating demand. Total delivered energy is approximately 40% compared with normal standard in Sweden.

04/02098 Influence of chloride in coal on PAHs emission: Yan, J.-H. et al. Gongcheng Rewuli Xuebao, 2003, 24, (2), 335–338. (In Chinese)

Existing non-domestic buildings tend to use more energy than expected. This paper investigates how the operational strategies of facilities management can contribute to reducing building energy use. A longitudinal case study of a higher education (HE) campus which was conceptualised with the objective of being environmentally friendly and energy efficient is presented. The paper reflects on the energy performance of the campus since its operation in 2001, based on 14 years of energy data and a detailed record of all initiatives undertaken by the campus’s facilities management (FM) team in order to optimise energy performance. The integrated FM strategy composed of low- and no-cost strategies, continuous improvements, ongoing commissioning and retrofits succeeded in reducing campus energy intensity from 174 to 87 kWh/(m2*yr), now outperforming most relevant benchmarks. This finding highlights the importance of operations and maintenance in reducing the energy usage of existing buildings. This presented findings draw on a single case only, which excels through a very detailed longitudinal dataset. Going forwards, the analysis of further cases is recommended to corroborate the findings. The presented results suggest that proactive operations and maintenance strategies in existing buildings can contribute towards significantly improving energy performance. The profile and competency level of facilities management personnel should consequently be raised strategically at the organisational and national/industrial policy level, whilst integrated design processes should be further expanded to include FM’s operational control and management in a holistically fashion.

Shade trees reduce building energy use and CO 2 emissions from power plants

Urban shade trees offer significant benefits in reducing building air-conditioning demand and improving urban air quality by reducing smog. The savings associated with these benefits vary by climate region and can be up to $200 per tree. The cost of planting trees and maintaining them can vary from $10 to $500 per tree. Tree-planting programs can be designed to have lower costs so that they offer potential savings to communities that plant trees. Our calculations suggest that urban trees play a major role in sequestering CO 2 and thereby delay global warming. We estimate that a tree planted in Los Angeles avoids the combustion of 18 kg of carbon annually, even though it sequesters only 4.5–11 kg (as it would if growing in a forest). In this sense, one shade tree in Los Angeles is equivalent to three to five forest trees. In a recent analysis for Baton Rouge, Sacramento, and Salt Lake City, we estimated that planting an average of four shade trees per house (each with a top view cross section of 50 m 2) would lead to an annual reduction in carbon emissions from power plants of 16,000, 41,000, and 9000 t, respectively (the per-tree reduction in carbon emissions is about 10–11 kg per year). These reductions only account for the direct reduction in the net cooling- and heating-energy use of buildings. Once the impact of the community cooling is included, these savings are increased by at least 25%.

95/05151 The application of ammonia/secondary refrigeration systems in retail food stores

Existing non-domestic buildings tend to use more energy than expected. This paper investigates how the operational strategies of facilities management can contribute to reducing building energy use. A longitudinal case study of a higher education (HE) campus which was conceptualised with the objective of being environmentally friendly and energy efficient is presented. The paper reflects on the energy performance of the campus since its operation in 2001, based on 14 years of energy data and a detailed record of all initiatives undertaken by the campus’s facilities management (FM) team in order to optimise energy performance. The integrated FM strategy composed of low- and no-cost strategies, continuous improvements, ongoing commissioning and retrofits succeeded in reducing campus energy intensity from 174 to 87 kWh/(m2*yr), now outperforming most relevant benchmarks. This finding highlights the importance of operations and maintenance in reducing the energy usage of existing buildings. This presented findings draw on a single case only, which excels through a very detailed longitudinal dataset. Going forwards, the analysis of further cases is recommended to corroborate the findings. The presented results suggest that proactive operations and maintenance strategies in existing buildings can contribute towards significantly improving energy performance. The profile and competency level of facilities management personnel should consequently be raised strategically at the organisational and national/industrial policy level, whilst integrated design processes should be further expanded to include FM’s operational control and management in a holistically fashion.