Some of the greatest potentials for improving building energy efficiency are found in the residential sector. Social housing, in particular, has drawn heavy research interest because it affects the welfare of large populations, is the source of significant energy consumption, and has outsize importance in the construction and regulatory sectors. Energy regulation in Mexico focuses on reducing the energy needed to cool buildings down, neglecting the importance of heating buildings built in the colder regions of the country. To address this gap, the present work focuses on the thermal behavior of social housing in the regions of Mexico with cold semi-arid climate. We found that thermal discomfort inside houses is primarily driven by low temperatures. We calculated annual heat flows in houses, visualizing heat gains and losses through each part of the building envelopes, and found that the highest heat flows occur through the floor. We also found that windows have the greatest heat transfer per unit area of all construction elements. We estimated the energy that each building would require if heating and air conditioning were used throughout the year to bring indoor temperatures within the range of thermal comfort. Finally, we used evaluation schemas from several countries to evaluate the energy demand per unit area (kWh/m 2 ) of several local houses in a typical year. The houses analyzed here presented low scores under these schemas.

Financial energetic problems oblige citizens to reduce the energy consumption. Accordingly, the recent research showed that major financial economies can be optimally achieved, by introducing some passive measures. The main objective of the current contribution is to investigate the impact of thermal insulation and compactness on energy efficiency. Following the assessment of the methodology, several input parameters were identified and economic insulation thicknesses were obtained. Finding revealed that the best effectiveness of solar gain has been observed for a better insulation and a good compactness, whereas a reduction of about 12.51% of energy needs can be achieved. Similar to the previous case, compactness has an attractive effect, provided that the building was well insulated. Furthermore, any variance cannot be occurred in economic insulation thickness by varying the building compactness. Unlike this remark, for a better compactness, a slight increase in the investment-return time has been noticed, following the energy bill reduction, which becomes more interesting. Hence, the comparative study averred that the previous passive concepts provide reduction in energy needs nearest 73.64%. Thus, reduction was nexus 82.17%, during cold season, and around 59.87%, in overheating period. As consequence, the studied structure type can be integrated in the buildings that have an energy label of “type C.”

Buildings' energy consumption has a great energetic and environmental impact worldwide. The architectural design has great potential to solve this problem because the building envelope exerts influence on the overall system performance, but this is a task that involves many objectives and constraints. In the last two decades, optimization studies applied to energy efficiency of buildings have helped specialists to choose the best design options. However, there is still a lack of optimization approaches applied to the design stage, which is the most influential stage for building energy efficiency over its entire life cycle. Therefore, this article presents a multi-objective optimization model to assist designers in the schematic building design, by means of the Pareto archived evolutionary strategies (PAES) algorithm with the EnergyPlus simulator coupled to evaluate the solutions. The search process is executed by a binary array where the array components evolve over the generations, together with the other building components. The methodology aims to find optimal solutions (OSs) with the lowest constructive cost associated with greater energy efficiency. In the case study, it was possible to simulate the process of using the optimization model and analyze the results in relation to: a standard building; energy consumption classification levels; passive design guidelines; usability and accuracy, proving that the tool serves as support in building design. The OSs reached an average of 50% energy savings over typical consumption, 50% reduction in CO 2 operating emissions, and investment return less than 3 years in the four different weathers.

The main objective of this study is to identify how climate variability and urbanization influence human comfort levels in tropical-coastal urban environments. San Juan Metro Metropolitan Area (SJMA) of the island of Puerto Rico was chosen as a reference point. A new human discomfort index (HDI) based on environmental enthalpy is defined to determine the energy required to maintain indoor human comfort levels. Regression analysis shows that both temperature and HDI are good indictors to predict total electrical energy consumption. Results showed that over the past 35 years, the average environmental enthalpy have increased, resulting in the increase of average HDI with clear bias due to urbanization. Local scale weather station data show a decreasing rate of maximum cooling per capita at –11.41 kW h/years and increasing of minimum cooling per capita of 10.64 kW h/years; however, for the whole Caribbean region, an increasing trend is observed for both minimum and maximum cooling per capita. To estimate human comfort levels under extreme heat wave events conditions, an event of 2014 was identified. The analysis is complemented by simulations from the weather forecasting system (WRF) at a resolution of 1 km, forced by data from the National Center for Environmental Prediction at 250 km spatial resolution. WRF model results were evaluated against observations showing good agreement for both temperature and relative humidity (RH) and improvements. It also shows that energy per capita in urban areas during a heat wave event can increase to 21% as compared to normal day.

A building energy simulation study is carried out to analyze the performance of a triple-hybrid single-effect vapor absorption cooling system (VACS) operated by solar, natural gas, and auxiliary electricity-based cogeneration. A high capacity small office building subjected to different climatic conditions is considered. The system is designed to continuously maintain a specified building comfort level throughout the year under diverse environmental conditions. Simulations are done at different generator temperatures to investigate the performance in terms of total annual electric energy consumption, heating energy, and the coefficient of performance (COP). The performance of the present VACS is compared with the conventional compression-based system, which demonstrates the electric energy and cost saving potentials of the proposed VACS. Simulation outcomes are well-validated against benchmark data from national renewable energy laboratory and energy conservation building code. Interestingly, it is found that beyond a certain collector area, surplus energy savings can be acquired with the present triple-hybrid VACS as compared to the compression-based cooling. Results also show that COP of the simulated system is in line with experimental values available in the literature. Finally, recommendations are given to operate the complete system on solar and biomass resources, which provide encouraging opportunity for agriculture-based countries.

A hybrid algorithm that combines genetic programming (GP) and genetic algorithms (GAs) that deduce a closed-form correlation of building energy use is presented. Throughout the evolution, the terms, functions, and form of the correlation are evolved via the genetic program. Whenever the fitness of the best correlation stagnates for a specific number of GP generations, the GA optimizes the real-valued coefficients of each correlation in the population. When the GA, in turn, stagnates, correlations with optimized coefficients and powers are passed back to the GP for further search. The hybrid algorithm is applied to the problem of predicting energy use of a U-shape building. More than 800 buildings with various foot-print areas, relative compactness (RC), window-to-wall ratio (WWR), and projection factor (PF) values were simulated using the VisualDOE TM energy simulation engine. The algorithm tries to minimize the difference between simulated and predicted values by maximizing the R 2 value. The algorithm was able to arrive at a closed-form correlation that combines the four building parameters, accurate to within 4%. The methodology can be easily used to model any type of data behavior in any engineering or nonengineering application.

This paper focuses on the thermal and energetic behavior of a building located in the Brazilian Amazon Region, a region climatically characterized by elevated temperatures and high humidity levels, where achieving adequate thermal comfort demands a high-energy consumption due to the use of air-conditioning systems. Therefore, different energy conservation measures (ECMs) need to be evaluated to reduce the thermal load for cooling. The use of a thermal insulation material on the west wall and on the roof, and a photovoltaic (PV) system integrated as an architectural element and adapted to the roof of the building are considered. The building is simulated with the software energyplus , with its thermal behavior and energy consumption analyzed for an entire year and for a chosen design day, defined with data measured by a weather station installed close to the building. According to the evaluations carried out, it is determined that the ECMs have a direct and major influence on the reduction of the thermal load for cooling, on the reduction of the effects caused by radiation with the shading on the eaves, and the reduction of the transmittance on the surfaces that were modified in the study. In terms of energy consumption and economic feasibility, the ECMs reach an annual energy saving percentage of 74% for the building chosen as the case study, and the solutions adopted provide the return of the financial investment, proving suitable for energy saving and economically viable for regions with similar climatic characteristics.

This paper presents a comparison of air conditioners using the conventional heating, ventilation, and air conditioning heat pumps and the one using solar heat stored underground, also known as shallow geothermal air conditioning. The proposed air conditioner with solar heat stored underground reunites practical data from an implementation of the heuristic perturb-and-observe (P&O) control and a heat management technique. The aim is to find out the best possible heat exchange between the room ambient and the underground soil heat to reduce its overall consumption without any heat pump. Comparative tests were conducted in two similar rooms, each one equipped with one of the two types of air conditioning. The room temperature with the conventional air conditioning was maintained as close as possible to the temperature of the test room with shallow geothermal conditioning to allow an acceptable data validation. The experiments made both in the winter of 2014 and in the summer of 2015 in Santa Maria, South Brazil, demonstrated that the conventional air conditioner consumed 19.08 kWh and the shallow geothermal conditioner (SGC) consumed only 4.65 kWh, therefore, representing a reduction of energy consumption of approximately 75%.

The Net-Zero Energy Residential Test Facility (NZERTF) was designed to be approximately 60% more energy efficient than homes meeting the 2012 International Energy Conservation Code requirements. The thermal envelope minimizes heat loss/gain through the use of advanced framing and enhanced insulation. A continuous air/moisture barrier resulted in an air exchange rate of 0.6 air changes per hour at 50 Pa. The home incorporates a vast array of extensively monitored renewable and energy efficient technologies including an air-to-air heat pump system with a dedicated dehumidification cycle; a ducted heat-recovery ventilation (HRV) system; a whole house dehumidifier; a photovoltaic system; and a solar domestic hot water system. During its first year of operation, the NZERTF produced an energy surplus of 1023 kWh. Based on observations during the first year, changes were made to determine if further improvements in energy performance could be obtained. The changes consisted of installing a thermostat that incorporated control logic to minimize the use of auxiliary heat, using a whole house dehumidifier in lieu of the heat pump's dedicated dehumidification cycle, and reducing the ventilation rate to a value that met but did not exceed code requirements. During the second year of operation, the NZERTF produced an energy surplus of 2241 kWh. This paper describes the facility, compares the performance data for the 2 years, and quantifies the energy impact of the weather conditions and operational changes.

Buildings in major metropolitan centers face increased peak electrical load during the warm season, especially during extreme heat events. City-wide, the increased demand for space cooling can stress the grid, increasing generation costs. It is therefore imperative to better understand building energy consumption profiles at the city scale. This understanding is not only paramount for users to avoid peak demand charges but also for utilities to improve load management. This study aims to develop a city-scale energy demand forecasting tool using high resolution weather data interfaced with a single building energy model. The forecasting tool was tested in New York City (NYC) due to the availability of building morphology data. We identified 51 building archetypes, based on the building function (residential, educational, or office), the age of the building, and the land use type. The single building simulation software used is energyplus which was coupled to an urbanized weather research and forecasting (uWRF) model for weather forecast input. Individual buildings were linked to the archetypes and scaled using the building total floor area. The single building energy model is coupled to the weather model resulting in energy maps of the city. These maps provide an energy end-use profile for NYC for total and individual components including lighting, equipment and heating, ventilation, and air-conditioning (HVAC). The methodology was validated with single building energy data for a particular location, and with city-scale electric load archives, showing good agreements in both cases.

Energy addiction is regarded as the primary obstacle to humanity's sustainable future. The need to change lifestyles in consumer societies to become more sustainable is advocated without a clear understanding of what elements of modern life must undergo major transformations. One of the most overlooked aspects of this question is the role of buildings that serve as homes and workspaces. The energy use for maintaining such infrastructure, especially in urban areas, and operating key services like heating or cooling, lighting, delivering water, and collecting wastewater will inevitably grow as global population becomes increasing more affluent. This paper investigates the energy costs of several aspects of these key services in urban areas, specifically delivering and heating water and heating residential spaces in the five boroughs of New York City. It provides detailed geospatial calculations as an example of assessing energy costs based on physical principles (e.g., accounting for the effects of topography and building floor elevation to deliver water and heat, and energy losses in the water distribution system). The paper also serves as a demonstration of much-needed research to price out the cost of modern life in energy terms in order to identify major inefficiencies in our current urban infrastructure, as well as the potential for efficiency improvements. While these calculations do not directly incorporate observed data, the principles demonstrated here highlight the use of quantitative geospatial analyses (based on fundamental physics) in order to look at urban infrastructures, particularly for planning and designing new cities or rebuild existing ones.

Recent disruptions of communities due to natural hazard events such as hurricanes and earthquakes have led to increased calls for improved resiliency of the built environment. The “built environment” denotes constructed facilities such as buildings and bridges, as well as infrastructure systems such as power delivery, transportation roadways, and water utilities. “Resiliency” is defined here as the “recovery and adaptability” during and after events which disrupt civil infrastructure services. In the context of this paper, the critically important service is energy delivery, on which many other services such as communications and transportation networks depend. The robustness of the building energy supply can be significantly enhanced through on-site renewable sources such as photovoltaic panels coupled with storage batteries. The degree to which the energy demand is met by the on-site capacity in the future will be determined largely upon advances in renewable energy generation and storage as well as in efficiency gains for commonly used equipment and appliances such as lighting fixtures and cooling systems. In this paper, we propose an improved design approach for the energy capacity of existing and new buildings as part of a greater regional community in which the total energy capacity requirements are met through increasingly enhanced on-site permanent power links, as opposed to increased reliance on the existing power grid. The metrics for characterizing resiliency will be “robustness,” “redundancy,” “resourcefulness,” and “rapidity,” with the associated metrics for sustainability being self-reliance and intergenerational equity enhancement.

The environment of a regularly occupied space can be extensively improved by maximum utilization of natural light/daylight, which is available in abundance. In Indian climate, availability of sufficient day light in both direct and diffused form of radiation can lead to reduction in dependency on artificial lighting thus, decreasing energy demand for artificial lighting system. In this study, an institutional building in New Delhi, India is analyzed for its daylighting characteristics. The academic block of a building comprising all categories of regularly spaces is modeled and simulated using Integrated environmental solutions - virtual environment (IES VE). The objective is to analyze the extent of penetration of natural light into these spaces of the building for reducing energy requirement for artificial lighting by studying a room, which performs the worst as per present case parameters. The conclusion puts forth the optimal solutions for utilizing maximum day light in a work space, complying with standards set forth by building construction council by utilizing the principles for increasing luminous flux level through visual light transmittance, window-to-wall ratio, and controlled usage of artificial lighting. Considering all these factors in the analysis, energy savings and carbon mitigation due to these savings in regularly occupied spaces are finally evaluated.

Today's building energy codes focus on prescriptive requirements for features of buildings that are directly controlled by design and construction teams and verifiable by municipal inspectors. Although these code requirements have had a significant impact, they fail to influence a large slice of the building energy use pie—including not only miscellaneous plug loads, cooking equipment, and commercial/industrial processes but the maintenance and optimization of the code-mandated systems as well. Currently, code compliance is verified only through the end of construction, and there are no limits or consequences for the actual energy used in a building after it is occupied. In the future, our suite of energy regulations will likely expand to include building efficiency, energy use, or carbon emission budgets over their full life cycle. Intelligent building systems, extensive renewable energy, and a transition from fossil fuel to electric heating systems will likely be required to meet ultralow-energy targets. This paper considers short and long-term trends in the building industry, lays out the authors' perspectives on how buildings may evolve over the course of the 21st century, and discusses the roles that codes and regulations will play in shaping those buildings of the future.

This research is to assess effects of a partition on thermal comfort, indoor air quality (IAQ), energy consumption, and perception in an air-conditioned space via computational fluid dynamics (CFD) analysis. The variables of indoor air are numerically determined before/after installation/removal of a partition. Accordingly, predicted mean vote (PMV) of thermal comfort, carbon dioxide concentration, rate of energy consumption in making up air, and an overall perception index are proposed to quantify effects in a partitioned space. For a case study, a partition is used to tightly separate a study area from a rest area in a library during peak time. The CFD analysis is performed so that the mean differences between the measured and simulated variables at 14 locations are less than 5%. After partitioning in the CFD analysis, it is found that the average PMV value decreases to −1.4 in the rest area, and it remains at −0.7 in the study area where occupants perceive a slightly cool sensation. In the study area, the carbon dioxide concentration increases to 450–500 ppm, while the rate of energy consumption increases by 8.3%. From the overall perception index of 0.9, the occupants feel spacious in the partitioned areas. Therefore, installing the partition is encouraged with the recommendation that cooling supply can be reduced for energy savings. It is apparent that the proposed methodology yields quantitative indicators for decision making of installation/removal of partitions. The interior investigation of partitions in buildings can be performed before making real physical changes.

Buildings account for a significant portion of the total energy consumption in the U.S., especially the energy-inefficient commercial building sector. As part of the future path toward realizing net zero energy buildings, innovative energy-efficient technologies must be developed. In this study, the potential of phase-change material (PCM)-enhanced constructions to lower heating, ventilating, and air conditioning (HVAC) energy consumption in a commercial restaurant building was investigated. A commercially available fatty acid based PCM product was selected due to their promising thermal and chemical properties. Differential scanning calorimetry (DSC) was used in isothermal step mode to accurately measure the latent heat energy storage of the PCM. A U.S. Department of Energy (DOE) commercial reference building model with a PCM-enhanced ceiling was simulated using a finite-difference conduction heat transfer algorithm in EnergyPlus to determine the effects of the PCM on the building energy performance. It was found that, although the PCM-enhanced ceiling had a beneficial stabilizing effect on the interior surface temperature of the ceiling, the zone mean air temperatures were not significantly altered. As such, minimal HVAC energy savings were seen. Future work should focus on active PCM systems, which utilize heat exchanging fluids to discharge the PCM to remove the stored thermal energy of the PCM during the night in summer, overcoming the fundamental issue of the passive PCM system returning stored thermal energy back into the building.

This study investigates the efficiency of application of phase change materials (PCMs) in a solar cooling system. The proposed system consists of an adsorption chiller and a latent heat storage unit (LHSU) containing PCMs. The PCM stores solar energy during daytime and at nighttime, the thermal energy stored in the PCM is utilized to drive the adsorption chiller. An auxiliary heater is also used to provide the required energy in addition to the LHSU. To verify the accuracy of the obtained results, the modeling of the solar adsorption system and the PCM unit are validated separately. Moreover, the whole system performance is verified by evaluation of the conservation of energy in the system. The performance of the system is compared with a similar solar adsorption chiller lacking LHSU. Also, the parameters which affect the performance of the LHSU are studied. It is found that application of LHSU decreases auxiliary energy consumption and increases solar fraction. Solar fraction goes up more if larger amount of PCM is used. However, there exists a maximum mass of PCM which can be charged during the sunshine hours. The maximum chargeable mass of PCM goes up by increasing the solar collector area, which leads to decreasing auxiliary energy consumption and increasing solar fraction. The results also show that enlargement of the hot water storage tank reduces auxiliary energy consumption and enhances solar fraction, but decreases thermal storage efficiency. In order to achieve higher thermal storage efficiency and also less auxiliary energy consumption, it is suggested to use average-sized hot water storage tanks.

In this paper, passive cooling strategies have been investigated to evaluate their effectiveness in reducing cooling thermal loads and air conditioning energy consumption for residential buildings in Kingdom of Saudi Arabia (KSA). Specifically, three passive cooling techniques have been evaluated including natural ventilation, downdraft evaporative cooling, and earth tube cooling. These passive cooling systems are applied to a prototypical KSA residential villa model with an improved building envelope. The analysis has been carried using detailed simulation tool for several cities representing different climate conditions throughout KSA. The impact of the passive cooling systems is evaluated on both energy consumption and electrical peak demand for residential villas with and without improved building envelope for five cities, representatives of various climate conditions in KSA. It is found that both natural ventilation and evaporative cooling provide a significant reduction in cooling energy use and electrical peak demand for the prototypical villa located in dry KSA climates such as that of Riyadh and Tabuk. Natural ventilation alone has reduced the cooling energy end-use by 22%, while the evaporative cooling system has resulted in 64% savings in cooling energy end-use. Moreover, the natural ventilation is found to have a high potential in all KSA climates, while evaporative cooling can be suitable only in hot and dry climates such as Riyadh and Tabuk. Finally, the analysis showed that natural ventilation provided the lowest electrical peak demand when applied into the improved envelope residential buildings in all five cities in KSA.

This paper presents a study which was conducted to evaluate the performance of a commercially available heat pump water heater (HPWH) with modified controls. The HPWH is first characterized experimentally under a series of different thermal conditions and draw parameters. The test tank contains a 1500 W electric auxiliary heater that provides on demand heat to the top 0.30 m (1 ft) of the tank, and a wrap-around heating coil. An air source heat pump (ASHP), using R-134A as the refrigerant, draws air from, and returns air to the surrounding space and provides heating to the whole tank through the coil. The tank has been tested using Canadian Standards Association draw profiles to characterize performance under different hot water demands. Electricity consumption and thermal flux is measured for each vertical tank section, and various performance metrics are calculated using energy balances. A trnsys model is then calibrated to the experimental data to allow for the flexibility of varying multiple parameters over various climates. Using this calibrated trnsys model, an optimal control strategy and tank setpoints can be determined for use in cold climates. As expected from previous work, there is a decrease in performance of the HP when heating the tank to higher temperatures to facilitate thermal storage, but the benefits from taking advantage of shifting electrical demand (of water heating) to space heating demand can outweigh the loss of performance.

A transient three-dimensional numerical solution is developed to analyze the thermal performance of thermo-active foundations used to heat and cool commercial buildings. Using laboratory testing data, the numerical solution is validated and used to carry out a sensitivity analysis to assess the most important design and operating parameters that affect the thermal performance of thermo-active foundations. It is found that the foundation depth, the shank space, the fluid flow rate, and the number of U-tube loops in each foundation pile are the main parameters that affect the thermal performance of a thermo-active foundation system. Based on the validated numerical solution, thermal response factors for a thermo-active foundation are developed, and implemented into a detailed building energy simulation program. These thermal response factors are then used to estimate the impact of installing thermo-active foundations on the total energy use of typical office buildings in representative US climates.