Reduce Building Energy Use Research Articles

Occupant perceptions of building information model-based energy visualizations in eco-feedback systems

While technology advancements are improving the energy efficiency of buildings, occupant behavior remains a critical factor in ensuring the effectiveness of such enhancements. To this end, numerous eco-feedback systems have been developed to reduce building energy use through influencing occupants' behaviors during building operations. Information representation is a critical component in eco-feedback systems, affecting the users' interpretation, engagement, and motivation to reduce energy consumption. Many studies have focused on using different charts and technical units or abstract and artistic visualizations to represent energy consumption. However, the effectiveness of such techniques varies across studies. Recent research emphasizes the need to integrate information representation strategies that balance numeric and aesthetic appeal. Concurrently, studies have called for increased adoption of a Building Information Model (BIM) during a building's operations phase to improve facility management. In this paper, we introduce a new eco-feedback information representation method that combines numeric and aesthetic appeal through leveraging spatial and color-coding techniques in BIM. The BIM-integrated energy visualization approach developed in this paper uses the Revit Application Program Interface (API) and allows users to visualize and compare energy consumption values in 2D and 3D views of a multi-family building through a color-coding scheme in an as-built BIM. The method is validated through a user survey that quantitatively and qualitatively assesses the proposed 2D and 3D BIM eco-feedback compared to more traditional bar chart based eco-feedback. Our findings suggest that 2D spatial, color-coded eco-feedback provides the optimal information representation, as it is easy to understand, while evoking engaging and motivating responses from users. This study advances our understanding of eco-feedback information representation while expanding BIM applications during building operations. These are important steps to address the human dimension of energy efficiency in the built environment.

Method for visualizing energy use in building information models

While technology advancements are increasingly improving the energy efficiency of buildings, occupant behavior remains a critical factor in ensuring the effectiveness of such enhancements. To this end, numerous eco-feedback systems have been developed to reduce building energy use through adjusting occupants’ behaviors. The information represented in an eco-feedback system affects the users’ engagement, motivation, and interpretation. In this paper, we introduce a new information representation method in which a building information model (BIM) is integrated with energy use information to enhance visual representation of energy use. The BIM-integrated energy visualization approach developed in this paper allows users to visualize energy consumption values of each building room through a color-coding scheme in an as-built BIM. Colors correspond to the levels of energy consumption in individual rooms compared to other rooms in a building, which enables a visually intuitive normative comparison for building eco-feedback systems. This representation may lead to increased user engagement in and improved interpretation of eco-feedback systems.

Effects of tree shading and transpiration on building cooling energy use

Building cooling energy use is regarded as the hot topic of building research due to its increasing trend at a rate proportional to the total direct energy use in urban areas nowadays. Urban greening as an effective countermeasure in reducing building cooling load has been attracting close attention although there is a shortage of quantitative measures for applying the general idea to a specific site or building. This study addresses this problem. The cooling effect of trees around buildings and the influence of tree characteristics on building cooling load reduction was quantified using microclimate field measurements and sap flow rate of trees. By integrating approaches of field measurements of microclimate and tree characteristics into EnergyPlus simulation of building energy use, the cooling effects of trees due to both shading and transpiration on buildings were quantified and discussed. Four scenarios were developed based on different tree characteristics for quantifying the influence of trees on saving of building energy use: Scenario 1 with treeless condition, Scenario 2 with existing trees condition in a case of Nanjing City, Scenario 3 with more tree shading condition, and Scenario 4 with more tree transpiration condition. The simulation results showed that compared to Scenario 1, Scenario 2 can reduce building energy use by 10.3% due to the benefits from existing trees shading and transpiration. More shading in Scenario 3 and a higher transpiration rate in Scenario 4 can reduce building energy use by 15.2% and 12.4%, respectively in comparison to that in Scenario 1.

Inter-Building Effect and Its Relation with Highly Reflective Envelopes on Building Energy Use: Case Study for Cities of Japan

The built environment with respect to building envelope designs and the surrounding micro-environment significantly affects building energy use. The influence of the inter-building effect (IBE) on building energy use cannot be ignored and thermal properties of building envelopes also largely affect building energy use. In order to evaluate the influence of IBE and its relation with highly-reflective (HR) building envelopes on building energy use, the building energy use under three simulated scenarios was quantitatively analyzed using the building energy optimization software “BEopt” for five cities of Japan. Analysis indicated that when the simulated building is neighbored by other buildings, an envelope coated with HR material is more effective than lowly-reflective (LR) material to reduce building energy use. A simulated single building without surrounding buildings and a LR envelope has the highest building energy use among the three simulated scenarios. This study also showed the influence of IBE on building energy savings is stronger in cities with lower latitudes.

Housing performance evaluation: challenges for international knowledge exchange

ABSTRACTDeveloping effective building performance evaluation and feedback processes is a vital part of global efforts to reduce building energy use and gain insight into the actual performance of buildings and technologies. Although attempts have been made to introduce internationally agreed models for these processes, it is clear that various countries are producing different approaches according to their cultural, institutional and policy differences. Knowledge exchange is potentially a key means of developing a shared understanding of values, meanings and practices in relation to building performance evaluation. This paper identifies cultural and institutional barriers in the European Union for international building performance communities of practice utilizing knowledge exchange, from an experiential ‘real-world’ perspective. The preparation of a 30-month research project to help develop building performance evaluation in Poland and an associated bilateral symposium is closely evaluated through an action research case study in terms of the stakeholders, the national contexts in which they operated and the key challenges they faced. Recommendations are then made in terms of the support needed to develop more responsive research programmes in relation to developing international knowledge exchange, and the capacity-building elements required for these international communities of practice.

Design and control optimisation of adaptive insulation systems for office buildings. Part 1: Adaptive technologies and simulation framework

The increasing insulation levels imposed by building regulations have the effect of reducing heating energy use, while increasing cooling energy use and/or reducing thermal comfort especially in summer. Adaptive insulation technologies could provide an opportunity to reduce building energy use while simultaneously improving indoor environmental quality, but there is a lack of information about the performance of these novel technologies.This paper is the first of a two part study, which aims to evaluate the performance of adaptive insulation. Part 1 proposes a simulation framework for optimising adaptive insulation design and control parameters and explains its implementation. The customised simulation strategy optimises design and control aspects of adaptive building envelopes by minimising the total primary energy use and thermal discomfort within a building. Moreover the simulation model for adaptive insulation is validated qualitatively. Part 2 applies this framework in a parametric study to explore the potential of adaptive insulation.

Energy and environmental consequences of a cool pavement campaign

Raising the albedo (solar reflectance) of streets can lower outside air temperature, reduce building energy use, and improve air quality in cities. However, the production and installation of pavement maintenance and rehabilitation treatments with enhanced albedo (“cool” pavements) may entail more or less energy consumption and carbon emission than that of less-reflective treatments. We developed several case studies in which a cool surface treatment is substituted for a more typical treatment (that is, a cool technology is selected instead of a more typical technology). We then assessed over a 50-year analysis period the changes in primary energy demand (PED, excluding feedstock energy) and global warming potential (GWP, meaning carbon dioxide equivalent) in Los Angeles and Fresno, California. The analysis considers two stages of the pavement life cycle: materials and construction (MAC), comprising material production, transport, and construction; and use, scoped as the influence of pavement albedo on cooling, heating, and lighting energy consumption in buildings.In Los Angeles, substituting a styrene acrylate reflective coating or a chip seal for a slurry seal in routine maintenance, or a bonded concrete overlay on asphalt (BCOA) without supplementary cementitious materials (SCM) for mill-and-fill asphalt concrete in conventional or long-life rehabilitation, induced MAC-stage PED and GWP penalties that substantially exceeded use-stage savings, primarily due to material production. Modified rehabilitation cases in which SCM comprised 21% to 50% of the BCOA’s total cementitious content by mass (portland cement+SCM) yielded smaller total (MAC+use) PED and GWP penalties, or even total PED and GWP savings. Trends in Fresno were similar, with some differences in GWP outcomes that result from Fresno’s longer heating season.The modified rehabilitation cases using BCOA with high SCM content yielded total GWP savings in each city; all other cases yielded total GWP penalties. The magnitude of the one-time GWP offset offered by global cooling from the increased albedo itself always, and sometimes greatly, exceeded the 50-year total GWP penalty or savings.In Los Angeles, the annual building conditioning (cooling+heating) PED and energy cost savings intensities yielded by cool pavements were each about an order of magnitude smaller than the corresponding savings from cool roofs.

Facilities management added value in closing the energy performance gap

Abstract 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.

Revisiting the climate impacts of cool roofs around the globe using an Earth system model

Solar reflective ‘cool roofs’ absorb less sunlight than traditional dark roofs, reducing solar heat gain, and decreasing the amount of heat transferred to the atmosphere. Widespread adoption of cool roofs could therefore reduce temperatures in urban areas, partially mitigating the urban heat island effect, and contributing to reversing the local impacts of global climate change. The impacts of cool roofs on global climate remain debated by past research and are uncertain. Using a sophisticated Earth system model, the impacts of cool roofs on climate are investigated at urban, continental, and global scales. We find that global adoption of cool roofs in urban areas reduces urban heat islands everywhere, with an annual- and global-mean decrease from 1.6 to 1.2 K. Decreases are statistically significant, except for some areas in Africa and Mexico where urban fraction is low, and some high-latitude areas during wintertime. Analysis of the surface and TOA energy budget in urban regions at continental-scale shows cool roofs causing increases in solar radiation leaving the Earth–atmosphere system in most regions around the globe, though the presence of aerosols and clouds are found to partially offset increases in upward radiation. Aerosols dampen cool roof-induced increases in upward solar radiation, ranging from 4% in the United States to 18% in more polluted China. Adoption of cool roofs also causes statistically significant reductions in surface air temperatures in urbanized regions of China (−0.11 ± 0.10 K) and the United States (−0.14 ± 0.12 K); India and Europe show statistically insignificant changes. Though past research has disagreed on whether widespread adoption of cool roofs would cool or warm global climate, these studies have lacked analysis on the statistical significance of global temperature changes. The research presented here indicates that adoption of cool roofs around the globe would lead to statistically insignificant reductions in global mean air temperature (−0.0021 ± 0.026 K). Thus, we suggest that while cool roofs are an effective tool for reducing building energy use in hot climates, urban heat islands, and regional air temperatures, their influence on global climate is likely negligible.

Genetic algorithm based optimization for photovoltaics integrated building envelope

A growing attention has been paid to building integrated photovoltaics (BIPV) when designing net-zero-energy buildings. Envelope features of large commercial buildings can be properly designed to both enhance PV integration and reduce building energy use. Many studies have been focused on predicting PV performance of designed systems or optimizing building envelope properties to reduce energy consumption. This study introduces an optimization framework using genetic algorithm (GA) via the GenOpt program to determine the best options for building envelope designs to reduce net building energy cost and increase PV utilization capacity/efficiency. A set of envelope design features were tested in this study, such as, building dimensions, window-to-wall-ratio (WWR), orientation, and PV integration placement, upon which the associated PV and building energy cost are evaluated and compared. Cubic commercial buildings commonly found in Egypt were used to demonstrate the application of the proposed optimization process. The developed tool can help designers to determine the optimal envelopes with appropriate BIPV options from both energy and economic perspectives.

Structural, geographic, and social factors in urban building energy use: Analysis of aggregated account-level consumption data in a megacity

Residential and commercial buildings comprise approximately forty percent of total energy consumption and carbon dioxide emissions in the U.S. Yet, while California spends $1.5 billion annually on energy efficiency programs, limited research has explored how building energy consumption varies within cities, including the social and structural factors that influence electricity and natural gas use. We present results from an analysis of aggregated account-level utility billing data for energy consumption across the over two million properties in Los Angeles County. Results show that consumption in L.A. County varies widely with geography, income, building characteristics, and climate. Several higher-income areas have greater total energy use per building even in cooler climates, while many lower-income regions rank higher for energy use per square-foot. Energy consumption also correlates with building age, which varies widely throughout the region. Our results demonstrate the many complex and interrelated factors that influence urban energy use. While billing data is critical for devising energy efficiency programs that actually realize estimated savings and promote more sustainable cities, opening access to such data presents significant challenges for protecting personal privacy. The presented approach is adaptable and scalable to cities seeking to develop data-driven policies to reduce building energy use.

Hygromorphic materials for sustainable responsive architecture

Contemporary smart building systems typically aim to reduce building energy use by means of technologically enabled climate-responsiveness; however, these technologies lack the efficiency and elegance of naturally responsive mechanisms employing the inherent properties of available materials, such as the moisture-induced opening and closing of conifer cones. This mechanism can be replicated to produce low-tech low-cost hygromorphic (moisture-sensitive) materials with the response driven by shrinkage and swelling wood. This paper explores the possibility of adaptive building systems based on incorporation of hygromorphic materials and argues that they present opportunities for architecture that is passively attuned to the variable natural rhythms of the internal and external environments, and that addresses a wide range of sustainability considerations.

IAQ and energy impacts of ventilation strategies and building envelope airtightness in a big box retail building

Heating, ventilating, and air conditioning (HVAC) systems in buildings are designed to provide thermally comfortable conditions and to maintain acceptable indoor air quality (IAQ). At the same time, the operating costs of HVAC systems are often a large percentage of the total energy consumption of buildings, which constitutes 40% of the primary energy consumed in the U.S. As efforts are pursued to reduce building energy use, which may involve reductions in outdoor air ventilation rates, it is important to consider the impacts of these measures on IAQ. To better understand the IAQ and energy trade-offs of various ventilation approaches, simulations were performed using the multizone airflow model, CONTAM, for a big box retail store in two climates. Annual energy simulations were also performed in EnergyPlus. Simulations included ventilating at the minimum outdoor airflow rate prescribed by the ASHRAE Standard 62.1–2013 Ventilation Rate Procedure during occupied hours and at a lower rate for 24 h a day. Additional cases included increasing the base outdoor air intake rates and changing the building envelope airtightness. Annual airflow and contaminant (carbon dioxide, formaldehyde, ozone, particulate matter, and a generic volatile organic compound) simulations were performed using emission rates from previous studies of retail buildings. This study demonstrated that ventilating at a lower rate for 24 h a day saved energy compared with ventilating at the higher rate prescribed in ASHRAE 62.1 and that the simulated indoor contaminant concentrations did not exceed common benchmarks or health guidelines.

Development of simple semiempirical models for calculating airflow through hopper, awning, and casement windows for single-sided natural ventilation

Natural ventilation is a promising approach to reducing building energy use if designed properly. Most of the previous design models for calculating airflow due to single-sided natural ventilation have been based on the assumption of simple openings. Since, most windows are not simple openings, but rather can create flow obstructions when opened; the impact of window structure on ventilation needs to be accounted for in order to accurately predict the ventilation rate in buildings. This paper presents an experimental and numerical evaluation of the impact of three types of windows—hopper, awning, and casement—on airflow in the case of single-sided natural ventilation. Semiempirical models for predicting the ventilation rate were developed for these window types and validated by both large-eddy simulations and full-scale measurements. In general, the predictions agreed with the measured results within an error of 25%, and the new models can be used for the design of natural ventilation systems.

A Framework for Delivering Targeted Occupancy Interventions to Reduce Energy Usage in Buildings

Policies aimed at reducing building energy use have often resulted in inefficiencies due to their higher costs, requirements to comply with regulations, incentives, and/or sanctions; and neglecting the impact of occupants on building energy use. To overcome these challenges, energy policy measures can be designed and implemented by identifying occupants’ behavior that significantly impact building energy use and relevant factors that may lead to sustainable behavior pattern. Therefore, this study presents a conceptual framework that proposes a multi-level intervention strategy that is tailored to varying occupants’ characteristics to produce and maintain energy use reduction in buildings over time. The framework is designed in two main steps: (1) identifying the occupants’ energy use and behavioral characteristics before and after the exposure of any energy efficiency intervention (e.g., education, persuasion); and (2) delivering targeted occupancy interventions based on occupants’ energy use and behavioral characteristics. This framework will assist decision-makers in formulating and designing effective energy policy tools at lower costs to deliver occupancy-focused interventions for reducing building energy use.

Analysis of Thermal Comfort and Energy Consumption in Long Time Large Educational Halls (Studios), Assiut University, Egypt

Reducing energy use in buildings is a critical component of meeting carbon reduction commitments. Architects and engineers are the major players, making technical improvements to existing buildings and designing new ones with higher standards. The aim of the present research is to analyse indoor thermal comfort and energy consumption inside the large educational halls of the Faculty of Engineering, Assiut University, for determining the acceptable operative temperature for student comfort. Two approaches are presented; physical measurements and comfort surveys for 6 naturally ventilated halls. Several parameters were measured: indoor and outdoor air temperatures, wind speed, globe temperature, CO2 concentration and relative humidity. A questionnaire adapted from ASHRAE 2004 was answered by 269 respondents selected from a total of 331 respondents.The results showed that the indoor temperature exceeds 28°C and is far from 90% acceptable comfort range with high PMV range and PPD >10, particularly for female students with Islamic head veils (hijab) and 83% of the students prefer a cooler indoor climate. The lighting power ranges from 50% to 75%, and laptops ranges from 25% to 44% of total nominal electrical power. Also, the students’ thermal sensation ranges between warm and slightly warm in the six halls. The results of this research provide information for future indoor cooling design strategies and energy efficiency in large educational halls.

Retrofitting the Electric Lighting and Daylighting Systems to Reduce Energy Use in Buildings: A Literature Review

This paper presents a literature review about energy-efficient retrofit of electric lighting and daylighting systems in buildings. The review, which covers around 160 research articles, addresses the following themes: 1) retrofitting electric lighting in buildings, 2) electric lighting energy use and saving potential and 3) lighting retrofit strategies. The retrofit strategies covered in the review are: replacement of lamp, ballast or luminaire; use of task-ambient lighting design; improvement in maintenance; reduction of maintained illuminance levels; improvement in spectral quality of light sources; improvement in occupant behavior; use of control systems; and use of daylighting systems. The review indicates that existing general knowledge about lighting retrofit is currently very limited and that there is a significant lack of information concerning the actual energy performance of lighting systems installed in the existing building stock. The resulting key directions for future research highlights issues for which a better understanding is required for the spread and development of lighting retrofit. (Less)

Improving infiltration modeling in commercial building energy models

As building envelope performance and heating, ventilation, and air conditioning (HVAC) equipment efficiencies are increasingly improved to reduce building energy use, a greater percentage of the total energy loss of a building can occur through 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. New strategies to incorporate airflow calculations into building energy calculations are proposed, which are based on relationships between infiltration rates calculated using multizone airflow models, building characteristics, including envelope airtightness, weather conditions, and HVAC system operation. The new strategies are more accurate than current approaches in energy simulation software and easier to apply than multizone airflow modeling.

공공청사 그린리모델링을 위한 데이터 정량화 시뮬레이션 모델에 관한 연구

In recent years, an international community has been trying to reduce greenhouse gas emissions and fossil energy usages in a variety of endeavors. In particular, a comprehensive and long-term policy for reducing building energy use is required since the building energy takes the biggest burden among the greenhouse gas emissions and the energy use. Advanced countries in the area of the reduction of building energy consumption, Germany, United Kingdom, United States, etc., had already established a long-term strategy and implemented the strategy to policies. EU countries established pan-national dimensions of policies such as EPBD (Energy Performance of Building Directive). A variety of regulations and supports for reducing the building energy consumption are implemented in our nation, and the corporate-driven new construction-oriented policy has been converted into the policy for improving energy performance based on existing public buildings. In this work, we propose a scheme to cut down the energy use for the existing public buildings through simulation studies. SBD (Simulation Based Design) is set up based on analysis of the existing public buildings and energy simulation tasks are performed. Then, a methodology is presented to improve the building energy efficiency implementing energy-saving elements obtained from the energy simulation tasks.

From “if only” to “social potential” in schemes to reduce building energy use

Much of the people-centered attention in current work on building energy use focuses on changing the behavior of individuals around a fixed set of things and energy services. This work envisions policy interventions for reducing energy use that rest on motivating people to act on potential monetary savings or to prioritize contributing to the global good. These perspectives largely omit consideration of higher scale and more intricate social contexts, professional cultures, and expectations that shape the activities, habits, and practices behind energy use. Below we discuss a notion of “social potential” that affords a broader possible contribution of social sciences to improved understanding of building energy use and how policies might reshape this use. We begin with an overview of the basic genres of research on people and building energy use and outlines three common missed understandings evident in the energy efficiency industry's attention to people: (1) “If only they knew”; (2) “If only they could be made to care”; and (3) “If only they stayed home.” Beyond individuals, communities, and organizations, we suggest social potential as a formulation that complements and transcends the technical and behavioral savings potential concepts underpinning much of today's building energy efficiency policies, programs, and research.