In building design or research processes, building energy simulations are conducted using weather data. There are two types of the weather data for building energy simulations; one is the typical weather year (TWY) to estimate annual cooling/heating load and the other is the design weather data (DWD) to estimate maximum cooling/heating load. In this paper, we propose a new type of year weather data which can be used as both the reference weather year and design weather data, here called as the typical and design weather year (TDWY). The TDWY presented in this paper include each quantile values of multi-year observation data, which means that the TDWY is also used for the versatile design weather data. In this paper, we investigate more detailed property of the TDWY such as the simultaneity of each weather components.

Building dynamic simulation is a mature and advanced technique that has been used for decades to evaluate the thermal performance of building designs and existing buildings. Alternately, some researchers have developed reduced models that represent the thermodynamics of buildings using simple models based in real data. Lumped Parameter Models (LPMs), are lineal dynamic models that can be studied with the techniques developed in systems theory. This work identifies the LPMs that best represent 40 dwellings in the UK, and has applied system theory to study the response of those buildings in frequency to the driving forces of outside temperature, electricity and solar gains. The work has shown that the buildings present a response in frequency similar to low-pass filters with respect to outside temperature.

Temperatures in the Gulf Arab region exceed 50 Celsius during the summer, making cooling one of the biggest issues facing the region. This paper investigates the effect of wind speed, direction and temperature on the air-conditioning system thermal performance in an outdoor shopping and setting area. Moreover, two methods of conditioned air supplying will be tested using displacement diffusers and jet diffusers. The effect of different roof designs will be simulated. Some wind mitigation methods were tested like trees and perforated panels. A three dimensional Computational Fluid Dynamics (CFD) model was built to simulate the air flow and temperature patterns between the buildings. Mass and energy conservation equations were added to the model. K-Turbulence model was in the calculations. In order to validate the numerical model, wind-tunnel tests were carried out and compared with the air-flow patterns from simulations. Comparison between air flow simulations and wind-tunnel results yielded good agreement.

Airflow patterns within the hospital operating rooms (OR) determine the levels of air speed, temperature, and flow path of contaminants to and from the sterile and non-sterile zones. This paper with the help Computational Fluid Dynamics (CFD) analysis analyzes the effect of various HVAC configurations on the resulting airflow pattern, temperature distribution, and importantly flow of path of contaminants between the sterile and non-sterile zones. With the help of airflow visualization this paper shows the effective flow path of the contaminants. The analysis provided in this paper is useful to practicing engineers in the healthcare industry in designing the HVAC systems for the operating rooms.

An Efficient ventilation configuration of an Airborne Infection Isolation Room (AIIR) is essential for protecting Health care workers (HCW) from exposure to potentially-infectious patient aerosol. This paper presents the Computational Fluid Dynamics (CFD) study to predict airflow distribution patterns throughout the AIIR, air velocity vectors in the HCW’s region, streamline of an air particle from patient’s infectious source and the comfort working conditions for the HCW for a range of AIIR ventilation configuration design challenge.

Buildings impact human health. The design and operation of an indoor environment influences occupants’ well-being. Aerosol transmission has been defined as “person ­to ­person transmission of pathogens through the air by means of inhalation of infectious particles”. The source may be an infected person such as a flu sufferer sneezing. Aerosol generation can also happen via coughing, laughing or just exhaling. This paper focuses on investigating the spread of aerosols after sneezing in a ventilated office space and the length of time they reside in the breathing zone thus estimating the possibility of infection of another occupant.

This paper examines developing air conditioning systems in the playground zone of a stadium by employing several kinds of technologies to cool the outdoor spaces. The most serious challenge of air conditioning in a playground zone in stadium is controlling the temperature and humidity in the outdoor area and also the enormous energy needed by the cooling system to maintain thermal comfort conditions within the football playground area. The main task for the analyzed model was to ensure the better method to distribute air to achieve the human comfort level for players and reducing the cooling capacity of playground zone by using a large sunshade to reduce the sun's rays and maintain the stadium's temperature.

This paper describes the chiller selection design and procurement process for a building thermal management system. The design procedures described in this paper are based on those carried out during an energy efficiency engineering internship in a local Los Angeles company and thus serving as an example of real world training. This paper presents the results of a case study to replace chillers that are approaching the end of their useful life. This case study is an example of how engineering interns are exposed to the various ASHRAE Standards. The retrofit project was carried out according to specifications and drawing of the existing obsolete equipment and adhering to Standard 90.1 “Minimum Requirements for Chillers” and the ASHRAE “Chiller Life Expectancy” guidelines used to govern chiller selection and installation. Results for COP lift versus load and chiller load versus system load are presented in the paper.

Louvers (or vents) are primarily used in air conditioners, fans and air-coolers for directional circulation of air in a confinement. Hence, it is of interest to determine the downstream flow field characteristics of air passing through these louvers for cooling and ventilating the confinement. A detailed Computational Fluid Dynamics analysis can be done by resolving all the geometrical features of the louver and setting the appropriate boundary conditions. However, this involves high computational effort, especially, in case of physical movement of the louvers for time-varying directional delivery of the air. The central aim of this research is to develop a rapid airflow model which can replicate similar downstream flow characteristics while obviating the necessity to geometrically resolve the louver. This paper examines the results of this research.

Air finned-tube evaporators and/or condensers, are the predominant type of heat exchangers used in building air conditioning applications. The compact V-shaped, or sometimes called A–shaped, finned-tube heat exchanger installation considerably enhance the capacity of heat transfer by allowing the maximum number of coils installed in a given space and increasing the total surface area of heat transfer. On the other hand, this design configuration creates noticeable problems of uneven distribution of air flow velocity over the heat exchanger surfaces, which decreases the energy efficiency of the air conditioning system. This paper uses computational methods to investigate the problems of mismatch between the air and refrigerant flow distributions and propose different engineering solutions at air flow side as well as refrigerant flow side to remedy the problems.

Streamwise longitudinal vortex generation is a promising method for enhancing air-side heat transfer performance of heat exchangers in a range of applications. In this paper, the vortex-enhanced air-side flow and heat transfer for offset strip-fin array is studied with an emphasis on understanding the relation between flow structure and heat transfer. The flow and heat transfer behavior of the baseline offset strip-fin geometry has been thoroughly investigated both experimentally and numerically in the literature. However, numerical modelling of vortex generator (VG) enhanced offset-strip fin array has not been reported. The predictive capability of the model in terms of the local flow and heat transfer characteristics is evaluated in such geometry for both baseline and enhanced cases.

Currently, the taxonomy of HVAC system and components has various basis, which can get quite complex because of the various components and system configurations. In addition, some of the system names might be commonly used in a confusing manner, such as “unitary system” vs. “packaged system.” Without a systematic classification, these components and system terminology can be confusing to understand or differentiate from each other, and it creates ambiguity in communication, interpretation, and documentation. It is valuable to organize and classify HVAC systems and components so that they can be easily understood and used in a consistent manner. This paper aims to develop a systematic classification of HVAC systems and components.

Passenger comfort and ventilation efficiency in cars have attracted the attention of scientists and car manufacturers during the last years due to their potential of improving thermal passenger comfort, increasing efficiency and attended energy reduction. Nowadays, state of the art for the ventilation of passenger compartments of cars is mixing ventilation (MV) which is based on a high mixing degree of inflowing air with cabin air. In cooling cases, this is realized by high-momentum jets of cold air, which enter the cabin at the dashboard. Among the potential benefits of new developed ventilation concepts, are an increased thermal passenger comfort by reducing draughts and simultaneously energy saving potential by increasing the heat removing efficiency (HRE). The latter is of great importance especially for electrically powered cars to improve their range.

Improving comfortable environmental conditions for passengers has been the airlines’ interests in the recent decades. This paper discusses air distribution systems and factors affecting the goal of a healthy and comfortable environment for the passengers and cabin crew. Research was done by using ANSYS FLUENT 17.0 with new features. The standard air distribution systems used in recent air cabin are combined between mixing ventilation and personalized ventilation and this study makes a simple applicable modification on the ventilation system that improves the ventilation efficiency, thus protecting the passengers from being infected by each other. Commercial airplane environmental control systems (ECS) currently mix air ventilation systems, which are necessary to make a safe, thermally comfortable and healthy cabin environment.

A number of studies have shown that air distribution systems on the thermal comfort of occupants can vary depending on locations of diffusers and return outlets and types of ventilation systems. However, few studies have focused on air distribution strategies for serving multiple zones and their effects on local air quality and thermal comfort. Simulation results indicate that temperature distributions of two rooms were a strong function of ventilation type. However, indoor air quality of two rooms was significantly affected by both a ventilation type and an operation strategy. The results suggest that careful consideration is needed for designers and managers in selecting and operating air conditioning system to maximize the ventilation effectiveness and the thermal comfort in multiple zones.

Air-conditioning systems are often designed based on the model experiment and the numerical simulation. However, such study methods spend much time and costs in order to obtain the result. Therefore, the prediction method of indoor thermal environment with less time and cost is required. As for the practical use period, the air-conditioning system controls the supply air temperature and the airflow rate based on the feed-back control system which has temperature sensors. In this paper, Contribution Ratio of Indoor Climate (CRI) is employed to predict the distribution of the air temperature for the sake of the more efficient control system. The vehicle cabin and its air-conditioning system are focused because in-vehicle environment is a relatively severe condition compared with indoor environment of building. The purpose of this paper is to investigate the prediction accuracy of the air temperature in vehicle with CRI in order to clarify its applicability.

As households are being required to be more energy efficient over the years, the energy consumption for producing domestic hot water (DHW) is receiving increasing attention. Hence, the design of hot water systems is becoming more important for a holistic approach to energy conservation. Current sizing for these systems is often based on estimations that obey empirical rules. An inaccurate evaluation of the hot water demand could lead to a poor hot water system design that is either undersized or oversized. This either means an insufficient amount of hot water available to occupants or an overpriced system that never gets to be used at its optimal operational point. Therefore, it is crucial to properly evaluate the hot water demand when designing hot water systems for dwellings. This paper discusses a stochastic tool constructed to generate hot water demand profiles for residential buildings using a 10-minute resolution.

In the residential housing sector, a strong correlation exists between occupant behavior and space heating energy use. In particular, the occupancy scenario (e.g., daytime absence, morning presence, etc.) has a significant influence on residential heating load profiles, as well as on cumulative heating energy consumption. The share of households characterized by different occupancy scenarios is a crucial assumption in order to accurately model the residential building stock heating demand. The choice of the most suitable occupancy model is a trade-off between complexity, accuracy and computational effort, as well as model integration at large scale. This paper analyzes the combined influence of different occupancy assumptions and different occupancy models on the housing heating loads for a UK building stock sample.

Occupancy information is important to building facility managers in terms of predictive control, safety, as well as the indoor environment quality. Previous works have addressed different occupancy counting and estimation solutions in different buildings or spaces. In this paper, we build up a test bed using the existing University lecture theatres to develop and compare four different occupancy counting methodologies. The paper addresses the occupancy counting challenge in educational building deployment scenario with large groups of people entering and leaving. Experiments have been conducted for three months with every 5 minutes data reporting interval. The results will be compared with the ground truth of real time pictures.

Accurate occupancy information is crucial to the demand response HVAC control. However, traditional passive infrared (PIR) occupancy sensors can only provide binary results of occupant presence without detecting the number of people in a room. In this paper, a low-cost bi-directional people counter was developed to determine the occupant number in a single entry room by detecting people entering or leaving the room. The developed people counter was designed to be installed in the doorway with a capability of recording the time and the number of people entering, leaving, and staying in the room separately. A field evaluation of the developed people counter was conducted in a single entry student lounge in a period of two weeks.

Flammability risk, in the event of a leak, can be lowered by reducing the potential for forming a refrigerant/air mixture that can reach the lower flammability limit (LFL) in the event of a leak into a confined space. The determination of effective room area and space volume has become critical to safety. This paper will describe an approach for determination effective room area, including methods to utilize adjacent connected spaces. Computational fluid dynamic (CFD) analysis was performed to support the justification for the methodology. An approach, utilizing the principles of natural convection and forced convection will be described for determining the effective room area and volume for individual rooms and connected rooms for unventilated spaces.

This paper presents details of a study which investigates the long-term thermal resistance (LTTR) performance of polyurethane insulation within discrete cold storage panels used in the US retail grocery environment. The research seeks to better define the potential benefit of extending the productive life of the insulation through longer cold storage service or through recycling into another insulative material. A total of ten U.S. retail chain grocery store sites were semi-randomly selected for the extraction of polyurethane panel specimens from decommissioned cold storage structures. Thermal performance of the cold storage panel specimens was determined by using the ASTM C518-10 Standard Test Method.

The need for refrigeration in the retail industry and specifically in supermarkets, currently accounts for around 30% to 60% of the total energy consumed in stores. A key characteristic of this consumption, is the high amount of low-grade (i.e., low-temperature) heat rejected by the condensation units to the ambient air. This paper focuses on the transcritical CO₂ (R744) refrigeration cycles and aims to assess whether the use of a water-cooled condenser rejecting heat to the soil via an intermediate closed water-circuit, can reduce the energy consumption, while also considering the economic implications of this modification.

In the past, the International Building Code (IBC) has required pressurized stairwells to maintain pressurization with all exit doors closed. Most jurisdictions in the U.S. are adopting the 2015 IBC that considers the status of exterior doors as opened or closed. A 2016 ASHRAE research project (RP-1447) has shown that a tenable environment can be maintained in stairwells with many open doors provided that the stair doors on the fire floor are closed. Smoke that leaks into the stairwell is quickly diluted resulting in a tenable environment in the stairwell. There are stairwell systems that are intended to maintain pressurization with a number of open doors, but many such systems are complex and have dangerous failure modes. This paper discusses these issues including suggested stairwell pressurization systems.

Delhi Metro is the world’s thirteenth largest metro system in terms of length and is India's first modern public transportation system built on state of the art technologies. The life safety systems are of paramount importance while carrying millions of passengers daily, the systems are required to be designed in such a manner that in case of any emergency situation the passengers shall be safely evacuated from transit network in minimum time. This paper discusses in detail the different life safety systems provided in the underground metro station building e.g. Smoke Management System, Fire Fighting System, Fire Alarm System, Emergency Power Supply System and Emergency Lighting System.

Mechanical Emergency Ventilation Systems (EVS) have been widely used in tunnels to mitigate fire hazards. However, a number of catastrophic tunnel fires have occurred and have raised questions about the effectiveness of the current tunnel fire safety systems. This paper discusses life safety issues that need to be considered in designing different types of the EVS commonly used in tunnels including transverse and longitudinal ventilation systems. It also discusses how airflow induced by the longitudinal and transverse ventilation systems could impact on the fire development and smoke dispersion in the tunnel. Tenability along the length of the tunnel produced by each type of the ventilation systems is also examined.

A hybrid-GSHP project currently being developed will investigate the economic and technical feasibility of a system using a water-to-air heat exchanger as an ancillary heat exchanger. The project has been planned to be developed in three phases, in order to have one year data for each phase. This paper describes the research facility, the concept of the hybrid-GSHP to be developed in three phases, and the energy performance of the system in Phase I from the data collected.

Residential zero net energy/low energy buildings require integrated renewable energy air conditioning systems especially in harsh climates such as Phoenix, AZ. In this paper, the thermal as well as economic performances for three types of residential-scale solar-powered heat pump systems is compared. The systems selected for this study were silica gel-water adsorption, single-effect LiBr-water absorption (both thermally driven), and solar photovoltaic (PV) powered vapor compression systems. An hourly building simulation model was developed for a single-family house in the Phoenix, Arizona, USA metropolitan area and performance of each of these systems was determined to satisfy the hourly cooling demand. The effect of solar collector area and storage capacity was also investigated.

Residential air conditioning represents nearly half of peak electrical demand on the Texas electricity grid during the summer, so finding ways to reduce peak demand have significant value for homeowners and grid operators. Thermal storage systems provide a means of shifting air conditioning load off-peak while maintaining cooling operation and thermal comfort levels, but are typically not deployed at the residential level due to cost constraints. This paper discusses the design and pilot testing of an integrated thermal energy and rainwater storage system (or ITHERST) for a small residential house. The paper summarizes the system design, describes the testing process and preliminary results, and concludes the report with a discussion on lessons learned and future work.

In California there are 70 non-residential and apartment house ZNE projects in 2015, whereas there are 21 ZNE projects in Japan in 2015. Hence, it’s supposed to be a good example for ZNE dissemination in Japan to clarify the problems toward ZNE dissemination in California. This paper addresses the energy performance of a ZNE office building in Northern California from the perspectives of simulation, measurement, verification, and code compliance. Simulations of the building’s energy use were undertaken during the design stage to demonstrate code compliance and measurements of actual energy use were taken for six months after occupancy.

Occupancy plays a significant role in the amount of energy used in buildings and their presence is stochastic in nature. There is extensive evidence to suggest that buildings usually do not perform as well as predicted by energy simulation. Use of unrealistic occupancy data as an input of building energy modelling (BEM) is a major reason behind it. As a result, large discrepancies are being observed between predicted and actual energy performance, typically averaging around 30% and reaching as high as 100% in some cases. This paper covers research that aims to develop an occupancy prediction model using Artificial Neural Network (ANN) for improving the accuracy of building energy simulation.

The increase in the electricity bills and the new opportunities to participate in the electricity market has encouraged companies with activities not related to the energy industry to engage and actively participate in the electricity market to reduce costs and become more competitive. With the overarching goal of making cost-effective investments and decarbonizing their operation, the first step to improve these companies’ bottom line is to comprehend their electricity costs. This paper focuses on detailing a methodology to model electricity commercial bills and generate real-time price curves; thus allowing customers to calculate their half-hourly true cost of electricity and to assess the challenges of reaching net zero energy buildings for different UK regions and connection voltage levels, across every month up to the financial year 2019-20.

An accurate building energy forecasting model is the key for real-time control of advanced building energy system and building-to-grid integration. Feature selection, the process of selecting a subset of relevant features, is an essential procedure in data-driven modeling due to its ability to reduce model complexity, increase model interpretability, and enhance model generalization. In building energy modeling research, features are often selected purely based on domain knowledge. There lacks a comprehensive methodology to guide the feature selection process when developing building energy forecasting models. In this research, a systematic feature selection procedure for developing building energy forecasting models is proposed in consideration of statistical data analysis, building physics and engineering practices. The procedure includes three main steps: (Step 1) rule-based feature pre-selection process based on domain knowledge. (Step 2) feature removal process through filter methods to remove irrelevant and redundant variables. And (Step 3) Using wrapper method to obtain the best combinations of features. A case study is presented here using simulated building energy data that are generated from a medium sized commercial building (a DOE reference building). In this study, the energy forecasting model generated by using the proposed systematic feature selection process is compared with other models such as a model that uses conventional inputs, and a model with single feature selection technique. The comparison result shows that, in terms of cross validation error, the model with systematic feature selection process shows much better model performance than other models including that with conventional inputs and that uses only single feature selection technique.

Tenability analysis along with computational fluid dynamics (CFD) are recognized methods of atrium smoke control analysis by NFPA 92, Standard for Smoke Control Systems. Tenability analysis evaluates the following threats to life: toxic gas exposure, heat exposure, thermal radiation exposure, and reduced visibility. In dense smoke, people see poorly and often become disoriented which prolongs exposure time of the other threats. Also falls from balconies can result from reduced visibility. This paper discusses these threats as they apply to atria smoke control and how tenability analysis can be incorporated in CFD simulations of atrium smoke control systems.

High-rise building fires often lead to disastrous and enormous losses if the fire smoke is not well controlled. This study uses the CFD model, Fire Dynamics Simulator (FDS) developed by the US National Institute of Standards and Technology (NIST), to model the fire smoke spreads and control strategies in a full-size high-rise building. The building is a 302-feet (92 meter) high-rise with two 20-story towers, three-story ground level parking spaces, two stairwells and one elevator shaft. The modeled fire smoke control system is a hybrid venting system with mechanical fan installed at the top of the stairwells. Neutral plane level, smoke temperature and smoke flow inside the building were studied based on the simulation.

The International Building Code and the Life Safety Code (NFPA 101) recognize that smoke-protected assembly seating, which is not subjected to smoke accumulation within or under a structure, subjects occupants to a lesser hazard from the accumulation of smoke and fumes during a fire event. The codes therefore have less-stringent requirements for design and layout of the means of egress for smoke-protected assembly seating, including reduced aisle widths per seat served and greater maximum travel distances. These less-stringent requirements provide increased use of space and flexibility in the design of assembly seating. This paper provides an overview of the use of CFD models in the design of smoke control systems for smoke-protected seating. Examples of smoke-protected seating in various settings, including arena seating and large theaters, are also discussed.

Thermal response tests (TRTs) are often conducted to inversely estimate the design parameters of borehole heat exchangers (BHEs); those are the effective thermal conductivity of ground and borehole thermal resistance. TRT can only provide the design parameters of a borehole heat exchanger, but it cannot provide the transient heat exchange rate of installed BHE which represents the actual performance of installed BHE. This paper proposes an estimation method of TPT that can provide both the thermal performance of BHEs and design parameters that usually obtained from TRT. Results showed that the performances of BHEs strongly depend on the inlet temperature. Additionally, transient heat exchange rates obtained from TPRTs provide valuable information on BHE performances that can be used for the design of BHEs.

The heat recovery ground source heat pump (HR-GSHP) system that has several types of GSHPs for different uses connected in the ground heat exchangers yields two types of heat recovery effects. The first one is the direct heat recovery effect obtained by operating the several types of GSHPs. The second one is the indirect heat recovery effect that utilizes the underground thermal storage effects and is brought by alternately operating the several types of GSHPs in the short term. By utilizing these two effects, the HR-GSHP can yield both energy saving effect and drastic reduction of the ground heat exchanger’s total length. This paper investigates the design and operation method of the HR-GSHP system.

In office buildings, the use of a Gas Heat Pump air-conditioning systems may be able to meet thermal demands with the same efficacy as a conventional electrical system while reducing energy demand of the whole building. This paper investigates technically, ambient and economically the substitution of a conventional air-conditioning system of an existing office building by a Gas Heat Pump air-conditioning system. The analysis was conducted through a data assembling of the potential of retrofit of operating office buildings in the city of Sao Paulo; through interviews with mechanical engineers and consultants; and through a case study developed in an existent office building, using computer simulation to evaluate energy performance of different air-conditioning scenarios.

One of the most important relationships in the commissioning process is between the commissioning agent, the owner and the engineer of record (EOR). A relationship that requires ongoing coordination with common goals defined from the beginning of the project. But what happens during Design-Build projects when the relationship between the EOR and contractors may result in different goals and can cause a conflict of interest? This paper provides a resource for all commissioning agents participating in a design-build project and offers guidelines to use to navigate from design to construction and to occupancy as effectively as possible.

This paper addresses issues from DGNB refurbishment and explores how a design process can be streamlined to address refurbishment and still preserve the gains from IED. Registration of the existing conditions is a prerequisite for a good design process where the software tools developed to ensure low energy consumption and good indoor climate can be used, and 3D scanning is therefore making a new and important contribution. The paper includes case studies of both ideal and applied design processes from an architectural office that specializes in sustainable projects.

Automated fault detection and diagnosis (AFDD) methods, followed by corrections, have the potential to greatly improve a building and its system’s performances. Existing AFDD studies mostly focus on component and sub-system AFDD. Much less effort has been spent on detecting and diagnosing faults that have a whole building impact. In this paper, an integrated data driven method: Pattern Matching Principle Component Analysis method, is developed and applied for whole building fault detection. Real building data that contains artificially injected faults and naturally occurred faults are used to evaluate the method’s accuracy and false alarm rate. The method presents great potential to be a cost-effective and accurate whole building fault detection strategy.

This paper explores opportunities for, and impacts of potential regulated energy performance and emission reduction standards for existing buildings in British Columbia. It includes evaluation of four standards – Standard 100-2015, Standard 90.1-2010 (BC Building Code), National Energy Code of Canada for Buildings-2015 and retro-commissioning procedures. Standards are applied to the existing building stock, except low-rise residential buildings, at the time of existing building alterations or repairs that trigger the BC Building Code or Vancouver Building Bylaw.

Today’s societal demands to control climate change are forcing HVAC&R equipment designers to consider new lower GWP refrigerants, some of which are slightly flammable under certain conditions. This paper supports setting a safety factor as low as 2 to 1 (50% of LFL) when setting the charges limits for A2L flammable refrigerants depending on the HVACR products application refrigerant charge and application height. Computational fluid dynamic (CFD) analysis was performed to support the justification of setting the safety factor. Numerous fast leak scenarios, 4 min leaks, were evaluated at various heights, room areas and refrigerant charge sizes. Maximum refrigerant charges for a large number of ASHRAE 34 classified refrigerants will be summarized for comparison purposes at various LFL endpoints.

Demands to control climate change are forcing HVAC equipment designers to consider new lower GWP refrigerants to replace traditional higher global warming potential (GWP) refrigerants, for example R134a and R410A. Understanding the environmental tradeoffs of using these new low GWP alternatives in HVAC products is becoming well understood but what uncertainty remains in understanding how they impact the on building sustainability. This paper provides an understanding of the impacts on total building sustainability through using building model simulations employing products using new lower GWP alternatives R513A and R452B to replace R134a and R410A.

There is significant interest in the adoption of low global warming potential (GWP) refrigerants. However, the heat transfer performance of these refrigerants is not well documented. This paper investigates alternate R410A refrigerants such as R32 and R452B. Fewer than 10 papers have been located which report heat transfer and pressure drop data for R32 and no papers have been located which report heat transfer and pressure drop data for R452B. The predicted performance of low GWP R410A alternatives will be compared to baseline values for R410A and impact on evaporator and condenser design will be discussed.

In recent years, the HVAC&R industry has been evaluating low global warming potential (GWP) alternatives to refrigerants such as R410A because of rising concerns over climate change due to their high direct GWPs. The industry is working to identify candidates that optimize performance, safety (flammability), and environmental impacts (GWP). R452B and R32 are two of the candidates under consideration. This paper presents measurements of system performance made on an R410A-based 100 RT air-cooled packaged water chiller with R410A (as baseline), R452B, and R32 refrigerants. The chiller comprised scroll compressors, a brazed plate evaporator, and microchannel condenser.

Thermal load management studies have been carried out at small and large scale, covering all the range from a single building to the country level, although prior research provides valuable information on the possible energy management schemes and gains, the large scale studies typically suffer shortcomings. This paper addresses those shortcomings focusing on the existing building stock. It describes a comprehensive tool to estimate the potential for thermal load management at large scale accounting for the buildings passive storage potential. The paper also describes the application to a 10 buildings case-study in Geneva (Switzerland) and quantifies the associated gains.

Energy efficiency in buildings is one of the key measures to tackle global energy and emission concerns. The large share of air conditioning in commercial buildings makes air conditioning systems as primary targets for retrofitting. This paper studies 50 commercial buildings in Singapore that have undergone chiller plant retrofitting. The energy audit reports from these buildings are studied in detail to gather data related to building energy consumption and chiller plant efficiency (measured in kW/RT). The energy utilization index (EUI) which is measured as the total energy per square meter is analyzed for these buildings before and after retrofitting.

Commercial buildings alone are responsible for 36% of the total United States electricity consumption, and on average 30% of this electricity consumption is wasted. One of the greatest challenges in improving building energy efficiency lies in the ability to do simple and non-intrusive disaggregation. Building energy disaggregation extracts system and equipment level energy signals from a whole building’s energy consumption data. This paper proposes a novel unsupervised non-intrusive building energy disaggregation technique using 15-minute interval whole-building energy consumption and weather data. The proposed disaggregation technique consists of an analysis loop with three steps.

Benchmarking energy use can help building owners and managers to assess building energy performance and to identify energy efficiency opportunities. Energy consumption data makes it easy to understand the energy use characteristics of each building, and can promote occupants’ awareness of building energy efficiency when providing an energy performance index developed from this data. As a way of improving energy efficiency in the building sector, the Korean government has developed a nation-wide integrated energy consumption database with more than six million building records. This paper introduces the framework of the national building energy consumption database and to analyze energy use characteristics of office buildings across the country.

Model predictive control (MPC) is becoming a popular algorithm for building HVAC supervisory control. One type of MPC for HVAC supervisory control is EnergyPlus Model-based Predictive Control (EPMPC), where an EnergyPlus model is used in MPC algorithm to predict future building performance. EPMPC could reduce the development cost of MPC by reusing the EnergyPlus model that is often developed during the design phase of a project. However, MPC, especially EPMPC, is much more complex and computation-intensive compared to traditional HVAC control logic; also, it needs to constantly acquire updated forecast data as inputs for computation, such as weather forecast data and occupancy schedule forecast data. Therefore, implementation of MPC to real HVAC systems is difficult. In this paper, a software framework of MPC for HVAC supervisory control is developed to facilitate implementation of MPC.

Intelligent building management systems aim to maintain thermal comfort and reduce energy consumption by learning occupant’s habits and behaviors. A component of these systems is dynamic scheduling, which ensures the HVAC system is only in use when the building is occupied. This paper develops dynamic schedules of building occupancy for an office building in London and estimate the effectiveness through a building simulation.

ASHRAE Guideline 36 aims to standardize a set of best practices for HVAC control. This paper compares a single-duct VAV terminal reheat strategy developed and implemented at Appalachian State University with the dual maximum strategy included in Guideline 36. The two strategies are similar but they differ in the details of implementation. The Appalachian State strategy controls the reheat valve with the zone temperature. Discharge air temperatures are monitored and when that temperature reaches 90 F, the VAV damper modulates to cap the discharge air temperature at the 90 F setpoint. Using numerical analysis and actual performance data, this study looks at the implications of this variation and compare operational outcomes with those established for the dual maximum strategy outlined in Guideline 36 and other energy conservation standards.

Small and medium sized commercial buildings, such as retail stores, restaurants and factories, often utilize multiple roof top units (RTUs) to provide cooling and heating for open spaces. A conventional control approach for these buildings relies on local feedback control, where each unit is cycled on and off using its own thermostat. Because a thermostat operates regardless of the overall building’s behavior, the conventional control approach could result in unnecessary energy use and high electrical peak demand via poor coordination among the units. The control solution is not site-specific and provides reduced energy consumption and peak demand with low sensor requirements. This paper provides recent results of long-term performance of the RTU Coordinator at field sites for small/medium commercial buildings.

This paper describes experimental results obtained from running a household dehumidifier overnight and comparing the temperature and humidity changes before and after turning on the dehumidifier, and comparing these changes to the amount of energy used to run the dehumidifier. This work is being performed in response to sustainability goals proposed by the United Nations call for “off-the-shelf” sustainable technologies in third world nations. The objective is to test the energy-saving qualities of dehumidifiers as a method of home heating. The data reduction of the household humidifier first calculates the amount of energy in the form of heat that is generated by the dehumidifier by comparing the change in temperature, time, kWh, and humidity, and applying these changes to the equation for the change in enthalpy in atmospheric air.

This paper presents a new, interior-space, environmental conditioning strategy, referred to as spatially adaptive heating, ventilating, and air conditioning (HVAC), where supply air locations within a room are repositioned in response to changing thermal loads or other room conditions. In order to quantitatively examine the technical merits of this concept, a computational fluid dynamics (CFD) model of a typical office was created using SOLIDWORKS Flow Simulation software and benchmarked using full-scale, experimental, velocity and temperature data from the literature. In light of promising results, a one-fifth scale model office was constructed to examine additional scenarios not covered experimentally in the literature and to validate computer simulations of these scenarios. Initial results from the scale model tests are described, and preliminary engineering concepts for achieving supply register relocation are presented. In addition, the opportunities, challenges, limitations, and potential for energy savings associated with this new strategy are discussed.

Radiant systems are increasingly being used for heating and cooling spaces due to its benefits like better energy efficiency, improved thermal comfort and IAQ. In addition, the radiant systems reduce the ductwork and are aesthetically pleasing. However, the effectiveness of radiant systems for optimal design need detailed study of impact of several parameters. In this paper, detailed CFD simulation of a typical room with radiant panel for cooling has been performed. Typical heat loads from human, lights and computer are considered in the model. Different scenarios of return diffuser location, on floor and on ceiling, are considered. Impact of radiation and buoyancy are modeled in the simulation and typical thermal boundaries are applied for walls, roof and floor. The detailed temperature and flow distribution obtained from simulation are used to evaluate and optimize the cooling system, supply flow requirements and diffuser locations.

The experimental performances of a dual-mode CO₂ heat pump system coupled with hot and cold thermal storage is investigated in this paper. This combined system was tested by controlling compressor frequency, expansion valve opening and hot and cold circulation water flow rates. Experimental results show that high compressor frequency benefits the combined system performances. Expansion valve opening affects the thermal stratification of thermal storage tanks very slightly. Low hot and cold water flow rates are good for the thermal stratification of thermal storage tanks although high water flow rates can enhance the COP of heat pump system; and thermal stratification in thermal storage tanks is one of the most important impact factors on the COP of heat pump.

Growing concerns about climate change, new decarbonization agenda, research for energy independence and geopolitical evolutions have led countries and industries to rethink their energy consumption. In this research for sustainability, major stakeholders in the UK food retail market are investigating pathways to reduce their carbon footprint. Low-carbon energy production technologies such as photovoltaic systems coupled with battery storage constitute potential solutions, also driven by rising electricity bills. The purpose of this paper is to develop an end-user optimization model assessing potential benefits of photovoltaic systems associated with battery storage for commercial buildings integration.

This paper discusses new methods for the operation of interacting simulating models. These methods provide tools to step into optimization of combinations of integrated energy systems. The main design issues that are addressed are hydronic flow system and the sizing of storage systems. The hydronic layout is important with respect to utilization of exergy i.e. water temperature, but the research also shows the importance of control strategies on energy savings. A proposed new hydronic layout and control design are described in this paper, as applied to heating, cooling and storage systems.

Mechanical ventilation accounts for a significant portion of the total energy consumption in large office buildings. The air needs to be transported over large distances through ducts, it requires filtration and needs heating and cooling to condition the ventilated space. Most offices in North America have closed windows, and manually opening these windows for natural airflow is discouraged as this can interfere with the operation of the building’s HVAC system. The recent drive for energy efficiency has created renewed interest in using natural ventilation to reduce energy consumption. This paper suggests a new approach to natural ventilation by using motorized windows controlled by the Building Automation System (BAS) in existing buildings. This paper presents a detailed breakdown and analysis of the simulation results, including an economic feasibility analysis of the application of BAS-controlled motorized windows.

The purpose of this research is to elucidate the influence of overhang of an exhaust hood on the capture and containment of the exhaust hood. The capture and containment performance depends on capturing and containing the thermal plume from cooking appliances. Larger exhaust hood openings seem more able to capture thermal plumes even if they expand due to air disturbance. However, provided that the ventilation rate is the same, the face velocity of exhaust hoods is low of the larger exhaust hood openings. This may prevent containment of the thermal plume from cooking appliances. We prepared an electric fryer and an electric noodle cooker. These devices are typical cooking appliances whose thermal plumes are weak and strong, respectively. The capture efficiencies of exhaust hoods were revealed, including the parameters of overhang length of exhaust hood and ventilation rate.

The K-12 education system is the largest public enterprise in the United States. Public K-12 schools employ approximately three million staff and enroll more than fifty million students. Public schools have an expenditure that includes funds for salaries, benefits, transportation, materials and energy use. Of these expenditures, energy use is often targeted for reduction, which sometimes results in reduced ventilation. While saving energy is desirable, it must be achieved without compromising student health. Lack of proper ventilation can result in a decrease of students’ attention and can cause health-related issues. This paper evaluates how the type of heating, ventilation, and air conditioning (HVAC) systems installed in schools and HVAC operation conditions affect temporal and spatial distributions of carbon dioxide (CO₂) concentration in classrooms.

This paper discusses a systematic experimental study of the effects of operating conditions (i.e. relative humidity and temperature of working air streams) on the transport of water vapor and CO2 (as a major indoor air contaminant) through a series of standard polymeric materials suitable for membrane media used in ERVs’. Results are reported for the permeation experiments of binary mixtures of water vapor and CO2 in five commercial polymers of two major types (glassy and rubber). The selectivity of water vapor over CO2 was also evaluated from permeation experiments. In general, the permeability results suggest that ERV exchangers using polymer membranes can achieve high latent effectiveness (i.e. very high water vapor permeability) over a wide range of operating temperature and relative humidity while maintaining very low CO2 permeability and very low EATR crossover rates (<1%) accordingly.

In most HVAC systems, water is usually delivered by several centralized pumps, which may reduce the pumping system’s energy efficiency because of unnecessary pressure loss. A decentralized pumping system is an alternative system that only circulates the minimum water required by the respective terminal unit and can reduce the excess pressure loss. This paper verifies the performance of the decentralized pumping system by conducting an experiment comparing centralized and decentralized pump systems under various water flow conditions in terms of their energy consumption in water delivery and their energy saving potential.

District cooling means producing cooled water in a centralized plant and distributing it in pipelines to a number of buildings to cool the air in each building’s air conditioning system. This paper investigates the effect of the wind speed and direction on cooling towers' thermal performance. Moreover, the distance between stacks, cooling tower fan speed, and effect of wind barriers were also simulated. A three-dimensional Computational Fluid Dynamics (CFD) model of a power plant cooling towers is utilized to assess the effect of flow circulation air on entering air wet bulb temperature under different ambient conditions and orientations.

Texas A&M University’s Main campus has its heating and cooling district to provide needs of both heating hot water (HHW) and chilled water (CHW) to over 230 buildings. Commonly, buildings exceeding the plant static pressure level experience negative pressure in their tallest parts, allowing air into the system that reduces heat transfer efficiency, causes noise, and increases corrosion. The negative pressure also results in consuming much more pumping power due to the requirement of lifting water above plant static pressure to above top building coil. This paper identifies the reason for the negative pressure, and a pressure distribution analysis was performed on the campus thermal loop.

Chiller plants are commonly used to provide cooling water to data centers. While chiller plants are designed for the maximum projected heat load, majority of data centers produce a fraction of the design load. Chiller plants that operate at partial load may not perform efficiently. Evaluating the performance of a working chiller plant is challenging because of the limited data available at the site. Moreover, it is not possible to know how the system will perform after making an adjustment to improve the efficiency. This paper illustrates the use of a scientific approach based on the Flow Network Modeling (FNM) technique for improving the operating efficiency of a real-life data center in Rochester, NY.