Reduce Building Energy Use Research Articles

Building retrofit optimization considering future climate and decision-making under various mindsets

Building retrofit is effective in reducing building energy use and improving comfort levels for existing buildings. However, conducting multi-objective optimization for individual buildings can be challenging due to the laborious computational cost of using white box models and the difficulty in visualizing and understanding the decision-making process. Additionally, the impact of climate change has not been fully considered for the post-retrofit lifecycle. This research proposes a pragmatic automated scheme that integrates a feature selection method based on marginal abatement cost analysis and variance-based sensitivity analysis, multi-objective optimization supported by non-dominated sorting differential evolution (NSDE) algorithm, tailor-made decision-making support under different mindsets, and tree-based retrospection scheme of decision-making pathways. The simulation engine used in this study is a low-order white box modeling tool developed by the research team. The proposed scheme was applied to two educational buildings with different thermal characteristics, and the results showed that a certain number of sampling sizes were needed to achieve reliable feature selection results. The hierarchical clustering based decision-making support scheme has demonstrated robustness in visualizing and supporting decision-making for Pareto front. Two retrofit mindsets - aggressive and balanced - were assumed in the decision-making process, and the proposed method produced distinct final solutions accoridng to the two mindsets. This framework can support informed decision-making, helping stakeholders implement sustainable practices and transition to a low-carbon built environment.

Building Energy Governance: Statutes and Guides on Retro-Commissioning in China and the United States

Reducing building energy use, a linchpin of climate change mitigation, is a daunting challenge across the world. Gaining increasing attention, retro-commissioning (RCx) is a systematic process that can improve building energy performance. Using a techno-legal lens to review statutes and guides on RCx, this study reveals that in China, a national standard on building commissioning has taken effect yet RCx statutes are hitherto not found. The United States has RCx statutes enacted over 14 states; scrutinizing the statutes of five cities unveils similarities and differences in their scope of control and compliance requirements. In the absence of a specific RCx statute, the guide of Hong Kong, China provides detailed guidance for energy saving practices. While these findings can serve as reference for other places planning to formulate laws or guidance on RCx, the need to further study the effectiveness of mandating RCx for reducing building energy use is highlighted. A conceptual analysis of cost variation with statutory control, which could help policymakers consider from an economic perspective whether or to what extent statutory RCx requirements should be imposed, is also illustrated. This not only contributes insights to the pursuit of an optimal balance between statutory control and voluntary action for energy reduction but also adds to the debate on building energy policies.

Daylight performance of horizontal light pipe and shading systems in office room with bilateral opening

Daylighting implementation in the building can reduce building energy use. Previous research about Horizontal Light Pipe and shading systems in the Tropics examined daylighting strategies in a room with a unilateral opening, which receives daylight through a window in one wall. The bilateral openings from two adjacent side windows have the potential to improve daylight distribution and have yet to be discussed in previous research. This research evaluates the daylight level and distribution of HLP and shading systems in a room with a bilateral opening from two adjacent windows. The research method is experimental with simulation using IES-VE (Integrated Environment Solution-Virtual Environment) as a tool. The Daylight Factor (DF) and Uniformity Daylight Factor (UDF) of a room with bilateral openings from two adjacent windows were compared with a room with bilateral openings, HLP, and shading systems. The results indicate that integrating HLP and shading systems in an office room with two adjacent side windows decreases the average Daylight Factor (DF) by 48.74%, bringing the average DF fulfilling the recommended DF level for the office room. HLP and shading systems improve the Uniformity Daylight Factor and percentage of sensor points with DF 2-5%, as high as 56% and 67.38%, sequentially.

Implications of lower indoor temperatures – Not cool for cold susceptible individuals across both sexes

Wider temperature ranges in buildings can reduce building energy use and prevent shortage of energy availability. However, humans do not perceive temperature equally and a general lowering of indoor temperature may in particular impact susceptible individuals. The discrepancy between individuals has been ascribed to sex differences, but is not well understood and could relate to heterogeneity in endogenous heat production or other personal parameters. We, therefore, evaluated individual thermal responses including physiological measurements of metabolic heat production in both men and women, identified, and via experiments, verified as cold sensitive or cold resilient. On average, the cold sensitive group had an 18 % lower resting metabolic rate compared to the cold resilient group when controlling for clothing and other important parameters for heat exchange. We observed a 0.9 °C difference in neutral temperature between sexes, but no difference in thermal perception or skin temperature. We concluded that cold susceptibility is not simply a matter of perception, but relates to a measurable difference in endogenous heat production. Currently mandated temperature setpoints at workplaces or recommended household temperatures do therefore not seem to discriminate between sexes as a result of sex-related differences in physiology, but they might have negative implications for cold sensitive individuals.

Assessment of a Decision-Making Model for Monitoring the Success of a Project for Smart Buildings

Objective: To express the usage of intelligent concepts in the architectural building construction field that are primarily concerned with reducing building energy use. Improved energy-saving methods and the use of environmentally friendly design principles are essential in this field. This type of managerial decision-making is necessary for the success of these types of projects. Methods: monitoring the performance of intelligent buildings use the cost variance (CV) and schedule variation as standard metrics to track the progress of a project based on the save energy concept. Also, this research conducted a comparative study on Building Information Modelling (BIM) and (MCDM) decision-making limitations as presented in the article. Analysis: the conventional technique, on the other hand, is unable to offer data on variance from typical performance levels. The main point based on Delphi results of construction cost variables has been observed 19 effective factors. Finding and Novelty: The RII observed that the most effective aspects of an intelligent building are the number of floors in the building, the kind of structural design, and the size of the shadow cast on the surface of the building. The Multi-Criteria Decision Maker (MCDM) observed significant differences in planned value (PV) and actual value (AC) results. In addition, as a result of the current approach, it is possible to track project costs and timelines more precisely. Doi: 10.28991/CEJ-2023-09-01-010 Full Text: PDF

Introducing extended natural ventilation index for buildings under the present and future changing climates

Natural Ventilation (NV) in buildings has a significant potential to reduce building energy use, provide thermal comfort and improve indoor air quality. NV potential is highly dependent on climatic conditions and may change over time due to global warming. To ensure a sustained and efficient NV design, it is necessary to identify the maximum potential of NV in a given climate and its sensitivity to climate change. Accordingly, this research aims to i) quantify the Climatic Potential of Natural Ventilation (CPNV) under present climate conditions and explore how this potential may change over time in the future in different Australian climate zones, ii) propose a new index named the Climatic Potential of Extended Natural Ventilation (CPENV) which identifies to what extent NV can be exploited if elevated airspeed requirements are met, and iii) evaluate the sensitivity of both CPNV and CPENV indices to global warming. Results showed that CPNV could be extended up to 18% with a required airspeed. The results also highlighted that the Total Climatic Potential of Natural Ventilation (TCPNV) could increase up to 27% or decrease up to 14.3% based on the present climate zone in the future.

Mandatory or voluntary approaches to green roof implementation: a comparative study among some global cities

Green roofs can deliver multiple environmental and social benefits by reducing the urban heat island effect, reducing building energy use and greenhouse gas emissions, improving air quality, providing habitat for biodiversity and access to the biophilia effect. Green roofs provide these benefits to differing degrees in different climate zones globally. Despite known benefits, uptake of green roofs has been slow. Different cities, globally, adopt various policies and programmes to increase their green roofs; the question is which approach is best? This research used an in-depth review, site visits and qualitative methods, to determine whether mandatory or voluntary approaches produced greater uptake. Green roof policies and practices from selected global cities, London, Toronto, Singapore, Rotterdam and Stockholm, Sydney and Melbourne were examined. Singapore’s voluntary approach led to the greater uptake of green roofs. The mandatory approach taken by Toronto, with financial grants provided meaningful outcomes. London and Rotterdam implemented useful voluntary programmes, and Stockholm required more time to evaluate the effectiveness of its voluntary approaches in increasing green roofs. A voluntary approach for retrofit and a mandatory approach for new build developments are suggested as recommendations for Australian cities. Given the increases in green roofs internationally, similar increases can occur in Melbourne and Sydney in Australia, and these findings may be transferable to other global cities investigating different approaches to the increased adoption of retrofitted green roofs.

Advocating for view and daylight in buildings: Next steps

With the exponential growth in population and commensurate increased density in urban cities, access to daylight and views to nature is being severely curtailed in buildings. In parallel, increasingly urgent demands to sharply reduce building energy use and associated greenhouse gas emissions are being made to mitigate climate change. There are many challenges and performance tradeoffs associated with the building facade (i.e., daylight and view versus solar and glare control); increased prioritization of health and well-being as a fundamental human requirement could adversely affect building energy-efficiency. Given the current state of knowledge on the effects of daylight and view on health and well-being in buildings, we identify critical needs in research, tools and technologies that if satisfied may enable more effective use of daylight and view in buildings within the constraints of climate change. Lack of knowledge regarding the complex causal mechanisms of window views on human factors is a severely limiting factor in forward progress. Current models and methods to derive bidirectional scattering distribution functions (BSDFs) will need to be modified. Developers of energy-efficient window technologies will need more guidance to shape product development. Advanced window technologies and integrated design can enable attainment of both health and well-being and net zero energy goals, but considerable work will be needed to make such options turnkey and broadly available.

Estimating energy savings of ultra-high-performance fibre-reinforced concrete facade panels at the early design stage of buildings using gradient boosting machines

ABSTRACT The selection of an energy-efficient building facade system, as one of the most important early-stage design decisions, plays a crucial role in reducing building energy use by controlling heat transmission between outdoor and indoor environments. This paper aims to evaluate the feasibility and applicability of gradient boosting machines in estimating the energy savings of different facade alternatives in the early-stage design of building facades. The energy performance of two competing facade systems was estimated for different scenarios using building energy simulations (i.e. EnergyPlusTM ). Three gradient boosting machines were developed based on the data collected from the simulation of thirteen building types in fifteen different locations (i.e. 195 scenarios). The prediction performance of gradient boosting models was compared with the building energy simulation results of two new building models that were not used in the database development phase to validate the models. Moreover, the prediction power of the trained gradient boosting models was compared with three common prediction models (i.e. Artificial Neural Networks, Random Forest, and Generalized Linear Regression) based on several performance metrics. The results showed the superiority of gradient boosting machines over other models in estimating total site energy savings, heating energy savings, and buildings’ cooling energy savings.

Tunable infrared transmission for energy-efficient pneumatic building façades

Thermal regulation of buildings in climates with daily and seasonal weather changes can prove challenging and result in high building energy consumption. While adaptable façades with tunable infrared transmitting properties could modulate solar transmittance through the building envelope and, as such, increase energy efficiency, available technologies to meet these needs are often expensive, relatively complicated, and challenging to implement in a lightweight form factor.Motivated by these limitations, this report presents a novel tunable light-modulating technology for energy-efficient pneumatic façades in the form of polydimethylsiloxane (PDMS) film with a thin gold surface coating. Sequential stretching and relaxing of this film results in strain-induced microscale surface cracks that can significantly modulate both visible and near infrared light transmission, and consequently, the material’s solar heat gain coefficient (SHGC).The material’s tunability has shown a significant potential to reduce building energy use, as assessed with building simulation software. The technology offers additional advantages for light modulation in pneumatic façades including real-time operation, ease of implementation and control, and predictable performance. Façade design guidelines for the integration of the infrared-regulating film into ethylene tetrafluoroethylene (ETFE) building envelopes and climate suitability are described, and a critical evaluation of material durability, optical clarity, and material costs are provided.

Multi-zone field study of rule extraction control to simplify implementation of predictive control to reduce building energy use

Model-based predictive control (MPC) has been promoted as a software-based energy saving approach for buildings since the 2000s. However, there has not been significant industry adoption of MPC using current approaches. This paper proposes and tests an approach to MPC using rule extraction (RE) that can be easily implemented in building controllers to override sub-optimal control. The resulting decision trees could be implemented by building control programmers to save energy when ambient conditions are predicted to satisfy the thermal requirements of the spaces. A detailed MPC algorithm using inverse models was implemented in 27 rooms of an institutional building to provide data for a classification learning approach. Cooling and heating season decision trees were generated based on the inputs and outputs of the detailed MPC algorithm. An ensemble and sample randomization were used to generalize the trees across rooms and prevent overfitting to individual rooms. Cooling season MPC and RE energy savings were 42% and 27% respectively and heating season MPC and RE energy savings were 18% and 33% respectively. Both algorithms also reduced the difference between the temperature setpoint and measured indoor air temperature compared to the reactive controls.

Optical and thermal performance analysis of aerogel glazing technology in a commercial building of Hong Kong

Abstract Improving the thermal insulation of glazing units is a common strategy of reducing building energy use for spacing cooling. This paper newly examined the application of aerogel glazing technology in Hong Kong by the means of laboratory testing and simulation. Nine prototypes of granular aerogel glazing were selected to examine their optical properties, and the measured optical properties of aerogel were used to calculate the total window thermal performance indices. A typical 40-story commercial office building was chosen for energy simulation to compare the thermal performance of aerogel glazing with different glazing technologies in Hong Kong. The results showed that aerogel glazing could achieve the promising reduction of window heat gain up to 57% and cooling energy up to 8.5% compared with double glazing. The heat insulation performance of aerogel glazing is even better than the double glazing with low-E coating in Hong Kong. Therefore, aerogel glazing can be a good alternative of glazing to comply with the existing local Overall Thermal Transfer Value (OTTV) requirement and to reduce the building energy use for space cooling in Hong Kong and other regions.

Simulation analysis of Macro-Packed Phase Change Materials (MPPCM) to reduce building energy use

This study sets up a zone-construction combination by constructing walls based on the classification of climates classified according to Korea’s energy saving design standards and the heat paring rate standard of the wall. There are four climatic divisions, C1, C2, S, and J, and we have used representative climate data for each climate. The target building was a residential apartment, which is the main residential type of large cities in Korea and the world. In the set combination, PCM of TES system is placed indoors, and applied PCM is n-hexadecane, n-heptadecane, n-octadecane with phase change temperature of 20-28 °C corresponding to room temperature standard. Each PCM is set at 0.1% to 0.9% of the area of the building. We used Energy Plus 8.7, a building energy simulation, and analyzed the energy saving and economic efficiency of the building. Saved energy was 2.71% on average and we were able to save up to 4.56%. In addition, we conducted an economic analysis, saving an average of 3.42% and saving up to 7.48%.

Trees in cool climate cities may increase atmospheric carbon by altering building energy use

Urban trees are a critical part of the ‘green infrastructure’ intended to make our growing cities more sustainable in an era of climate change. The potential for urban trees to modify microclimates and thereby reduce building energy use and the associated carbon emissions is a commonly cited ecosystem service used to justify million tree planting campaigns across the US. However, what we know of this ecosystem service comes primarily from unvalidated simulation studies. Using the first dataset of actual heating and cooling energy use combined with tree cover data, we show that contrary to the predictions of the most commonly used simulations, trees in a cool climate city increase carbon emissions from residential building energy use. This is driven primarily by near east (<20 m from building) tree cover. Further analysis of urban areas in the US shows that this is likely the case in cool climates throughout the country, encompassing approximately 39% of the US population and 62% of its area (56%, excluding Alaska). This work adds geographic nuance to our understanding of how urban shade trees affect the carbon budget, and it could have major implications for tree planting programs in cool climates.

Energy and hygrothermal performance of cross laminated timber single-family homes subjected to constant and variable electric rates

Cross Laminated Timber (CLT) is a panelized mass timber product suitable for sustainable building construction that can reduce building energy use and cooling electricity peak demand. Previous studies have shown that CLT has a market in the US for tall commercial buildings. However, most of the current CLT literature has not consider application in residential construction. Residential building energy use is highly susceptible to weather. Thus, it has the potential to benefit from using CLT as the envelope material given its natural massiveness and enhanced air-tightness. Furthermore, the construction advantages of CLT make it a candidate for rapidly growing residential areas. This study numerically analyzes potential energy savings when CLT is implemented in a single-family home in different US climates. A typical new wood frame home is compared against the same house implemented with CLT construction. The effects of increased thermal mass and reduced infiltration are taken into account in order to determine the impact of CLT on the energy consumption. This study also considers the use of variable thermostat setpoints to introduce precooling strategies with the objective of reducing cooling electricity energy cost when time-of-use (TOU) electricity rates are available. In addition, this study examines temperature and humidity changes in CLT homes using WUFI software, a wall assembly simulator used to analyze thermal and moisture transfer. The thermal changes throughout the wall assemblies indicate the enhanced sensible storage capabilities, insulation performance of CLT, as well as ensure that the CLT assembly is physically practical, with no significant moisture accumulation that can lead to rot or mold.

Building energy: a review on consumptions, policies, rating schemes and standards

The building and construction sectors account for more than one third of the global energy consumption. In order to understand the status quo of building energy around the world, a study, as reported here, reviewed the energy consumptions of the major countries/places, their energy policies and rating schemes and standards applicable to building energy use. The review shows that countries with abundant energy resources tend to consume more energy per person than those with less energy resources. Some developing countries have green building rating schemes in place, but many others have not adopted any building energy standard. For those countries who have the standards in place, they may find it difficult to implement the standards in reality. In addition, some new building energy standards have been released lately; studies that make reference to such standards are yet to be seen. Research in future should investigate how the building energy standards could be effectively adopted to reduce building energy use.

Do Mandatory Energy Audits Reduce Building Energy Use?: A Bayesian Analysis of New York City's Local Law 87

Cities are experimenting with a range of policy and regulatory tools to reduce energy use in the building sector as a pathway to substantial carbon emission reductions. Increasingly, cities are turning to policies that reduce information asymmetries and knowledge gaps through data transparency, focusing on existing buildings and the potential to achieve up to 50% energy savings through retrofit adoption. These include energy disclosure - or benchmarking - ordinances and, more recently, mandatory energy audit requirements. While energy benchmarking is a relatively low-cost mandate, energy audits impose non-trivial costs in terms of capital and time for building owners. The question we explore here is whether mandatory energy audits lead to reduced energy consumption over time. We collect detailed energy use and building attribute data from 2011 to 2016 for approximately 4,000 buildings in New York City and integrate with a unique dataset of mandatory energy audit reports for a randomly selected sample conducted in 2013 and 2014. We use non-parametric statistical tests and Bayesian regression to evaluate the impact of energy audits on building energy performance, compared to a control group of matched buildings not subject to the audit requirement. We find that mandatory energy audits have a modest negative impact on energy consumption, consistent with savings expected from low-cost energy conservation measures and retro-commissioning activities. The result reinforces the hypothesis that audits, by themselves, create an insufficient incentive to invest in energy efficiency upgrades at the scale needed to meet city carbon reduction goals.

Design and experimental analysis of a solar thermoelectric heating, ventilation, and air conditioning system as an integral element of a building envelope

This study presents an innovative concept of a compact integrated solar-thermoelectric module that can form part of the building envelope. The heating/cooling modes use the photovoltaic electrical current to power the heat pump. The experimental analysis was carried out and the results of coefficient of performance were in the range 0.5–1 and 2.6–5 for cooling and heating functions, respectively. The study demonstrates that thermoelectric cooler can effectively be used for heating, ventilation, and air conditioning applications by integrating with solar panels especially in cooling applications. The system is environmentally friendly and can contribute in the implementation of zero energy buildings concept. Practical application: In order to help address the challenge of climate change and associated environmental effects, there is continuous demand for new technologies and applications that can be readily integrated into day-to-day life as a means of reducing anthropogenic impact. Heating, ventilation, and air conditioning, as one of the largest energy consumers in buildings, is the focus of many researchers seeking to reduce building energy use and environmental impact. This article proposes using facades and windows that have an integrated modules of solar photovoltaic cells and thermoelectric devices that are able to work together to achieve heating and cooling effects as required by the building without requiring any external operational power.

Sensitivity analysis of design parameters and optimal design for zero/low energy buildings in subtropical regions

To reduce building energy use and mitigate CO2 emissions, zero/low energy buildings have attracted increasing attention. However, the impacts of the main design parameters and optimal design for zero/low energy buildings only provided with cooling in subtropical regions are seldom studied, and the objectives for building performance assessment and design optimization in such particular situations are not addressed sufficiently. In this study, the impacts of the main design parameters and optimal design for zero/low energy buildings in subtropical regions are studied. A holistic approach integrating sensitivity analysis and design optimization is developed for zero/low energy buildings. A new optimization objective is proposed, which considers annual energy consumption and winter thermal discomfort, for buildings without heating provision. A multi-stage sensitivity analysis approach is proposed to identify the key design parameters for design optimization. The key building design parameters are optimized to minimize the optimization objective using the genetic algorithm. A case study is conducted, using the zero carbon building (ZCB) in Hong Kong as a reference building, to illustrate the implementation steps and effectiveness of the proposed approach. This paper presents the identification of the key influential design parameters in the subtropical climate and the design optimization method of zero/low energy buildings as well as the procedures and the results of the case study.

Integration of passive PCM technologies for net-zero energy buildings

Due to the increasing energy demand for space heating and cooling, renewable energy power generation and integration of energy storage systems received attention around the world. A method to reduce energy demand of buildings is the application of thermal energy storage (TES) systems. This is due to the possibility of storing heat/cold energy to release it when required, which can tackle the temporal gap between energy demand and supply. In this work, phase change materials (PCMs) have been considered as a useful passive method. In the summer, PCMs can absorb the excessive heat during day time and release the stored heat during night time. A composite wall filled with different PCMs was developed and analysed using TRNSYS software with the purpose of integration into passive near zero building applications. The results show that the PCMs in walls can reduce building energy use on daily basis and help achieving the goals of a net zero energy building (NZEB) in future.