Demand controlled ventilation (DCV) systems use sensors—generally either CO₂ or occupancy sensors—to estimate the actual number of people in an area and supply only as much ventilation air as is needed at that time. This can save substantial energy over the traditional method of ventilation which assumes that all spaces in a building are at peak occupancy at all times. But while DCV has been in use for over 20 years and its theoretical impacts have been well demonstrated, little is known about the actual operation and energy performance of these systems in real buildings. And even less is known about the performance of DCV for complex multizone systems. This paper helps fill this information gap by covering a field study of DCV systems that we recently conducted in multizone HVAC systems in the upper Midwest. After gathering information on a broad number of actual DCV systems installed in this region, the authors have measured, analyzed and demonstrated the impact of DCV in a subset of six such systems.

The biowall is a plant-assisted air-filter that is integrated with the central HVAC system on a home to improve indoor air quality and has the potential to reduce energy consumption. The biowall concept has been evaluated in a laboratory setting and a pre-commercialization prototype has also been installed in a model home for further evaluation. This paper summarizes the laboratory and field demonstration work that has been accomplished since 2014. It is expected that a biowall can reduce the outside air requirements for IAQ by up to 50% which could subsequently reduce HVAC energy consumption by 30%.

Displacement ventilation systems have found increased usage in recent years and have been shown to reduce energy consumption while satisfying the required indoor air quality (IAQ) standard. The system takes advantage of thermal buoyancy effect to displace warm air and light containments above the occupant breathing zone. This makes the displacement ventilation system a good candidate for cooling spaces with high ceilings. Despite the advantages of this system there are still questions on the system ability in removing CO2, which has a higher molecular weight than air. The current paper investigates the CO2 concentration from occupants in an interior office with a displacement ventilation system.

Electricity consumption per capita has been gradually increasing by 8% annually during the past 10 years in the Kingdom of Saudi Arabia. One of the main reasons for this above-average growth rate is the utilization of low-efficiency electrical home appliances, which is encouraged by the low initial investment and the artificially low energy prices. In 2013, the residential sector consumed nearly 126 terawatt hours, which represents 49% of the country’s electricity consumption. This paper investigates the potential savings in primary energy that can be achieved by switching residential water heating and cooking appliances from electricity to liquefied petroleum gas (LPG).

This paper describes a single-circuit hot gas bypass defrost strategy, similar to those used in commercial refrigeration applications, for a residential heat pump. The hot gas bypass strategy does not require a reversal of the cycle, but instead bypasses some hot gas from the compressor discharge line through some or all of the circuits of the evaporator (outdoor unit) coil to remove frost. Similar defrosting strategies are successfully utilized in large-scale refrigeration systems, such as those used in supermarkets, but these methods are not commonly implemented in smaller systems for the residential or light-commercial markets. A prototype system was developed for investigation consisting of a manifold system that allows hot gas to be bypassed from the compressor discharge line through any or all of the five circuits on the outdoor unit coil.

This paper proposes the conditional demand analysis (CDA) methodology, which is relevant in electric energy consumption by main household facilities and suggests important variables that can affect CDA values, accordingly. Although households, particularly apartments, are considered the main primary energy- and electricity-consuming housing type in Korea, efforts on reducing electricity consumption by households are limited. The usage of energy is mainly focused on primary energy. Considering that many attempts have been made to reduce residential energy consumption, disaggregating total electric energy consumption into specific end-use level such as heating, cooling, ventilating, hot-water supply and lighting, is a very useful method. In general, by obtaining information on the energy consumed by each piece of equipment, we can easily determine the total electric energy consumed.

The first part of this presentation explores the relationship between tall buildings and energy use by examining the publically available data from municipal energy benchmarking ordinances. The analysis of this data examines correlations between building size, age, utility profiles and energy consumption.  The second portion of the presentation compares city benchmarking and CBECS data sets against a pool of newly designed/constructed tall building energy model simulations. The purpose of this analysis is to compare the simulated performance against actual consumption in order to better understand trends in new tall building design as well as assess if these simulations are reasonable representations of actual tall building performance.

Do tall buildings consume more energy per square foot than typical buildings? According to the Council on Tall Buildings and Urban Habitat, more buildings exceeding 200 m in height were constructed in 2014 than ever before. Is this increase in height accompanied by an increased EUI? Energy benchmarking data from New York and Chicago, two of America’s tall-building giants, is used to approach the question from an empirical perspective. Full building energy simulations are presented to approach the question from a modeling perspective. Governing principles of heat transfer, fluid dynamics and building physics are presented to approach the question from a theoretical perspective. Lastly, the audience is engaged to debate and settle the question for good.

Many buildings with large, high-bay areas suffer from high energy cost in the winter months due to inefficient equipment, poor system layout and thermal stratification. While various strategies are available to heat and ventilate the building, some technologies can meet these heating loads with greater energy efficiency, improved temperature control and other operational benefits. This presentation provides an overview of 100% outside air, HTHV (High Temperature Heating and Ventilation) direct-fired heating technology for high-bay commercial buildings and discusses the findings of a recent field study outside St. Louis, MO.

This paper describes the study of an IT office building where radiant cooling system and conventional VAV has been installed for the performance assessment. The paper details the calibration of whole building energy model to component level; lighting, equipment and HVAC components like chiller, pumps, cooling towers, fan etc. Also, a new methodology for the systematic selection of influence parameter has been developed for the calibration of a simulated model which requires the large time for the execution.

The design-build construction method presents opportunities and challenges to all the groups involved in a construction project.  This paper will explore how the mechanical and electrical designers and contractors addressed these opportunities and challenges for the recent Byron G. Rogers Federal Office Building modernization project in downtown Denver, Colorado.  The project involved approximately 500,000 square feet of renovation and deep energy retrofit in an existing high-rise building  which is anticipated to to be added to the National Register of Historic Places in the future. 

The heating, ventilation, air conditioning and refrigeration industry shows a trend toward increased adoption of condensing boilers in heating systems, but the full impact on design and construction is complex. The maximum efficiency of condensing boilers can significantly exceed that of non-condensing boilers at lower return water temperatures. However, in order to reach lower return water temperatures, coils must be properly selected. A standard coil selection exhibits a tendency to produce a smaller change in temperature with lower water temperatures. As a result, pumping energy increases due to the increased flow required to supply the same heat energy. This paper investigates the effect on overall system performance and construction cost of various heating system metrics with regards to condensing and non-condensing boilers.

This paper summarizes an experiment campaign on alternative refrigerant evaluation for R-22 and R-410A mini-split systems. The experimental evaluation was performed according to ANSI/ASHRAE Standard 37 and the performance was rated according to ANSI/AHRI 210-240 standard. The paper presents the relative performance (efficiency and capacity) of the alternative refrigerant compared to the baseline refrigerant at the different operating conditions. The paper ends with concluding remarks about the alternative refrigerants for R-22 and R-410A applications in high ambient temperature regions.

In this paper, the oil retention in a microchannel type evaporator was measured and its effects on heat transfer and pressure drop characteristics are presented. The microchannel heat exchanger was a single pass, aluminum louvered-fin type evaporator with multi-port microchannel tubes installed vertically.

Flammability testing studies were conducted to support a methodology to optimize GWP to flammability for blends of R32, R1234yf and R125. Performance modeling studies were conducted to guide the best design of experiments for the flammability testing that optimize performance. Minimum ignition energy and burning velocity characteristics were determined for various blends of R32, R1234yf and R125 to determine flammability characteristics. This paper will discuss the results of these studies.

Global pressure to control climate change is driving the development of new regulatory policies that restrict and/or lower the direct GWP impact of fluorocarbons (or F-gases). These demands have resulted in researching a whole new class of fluorocarbons called unsaturated fluorocarbons or commonly referred to as hydrofluoroolefins (HFOs).  This paper provides an overall assessment of the application of the new HFO refrigerant R-1233zd(E) in stationary HVAC chillers. The presentation also reviews thermodynamic cycle performance and heat transfer characteristics relative to R-123, R-245fa and R-134a in a centrifugal chiller application.

Regulatory and voluntary actions are beginning to limit the direct global warming potential (GWP) of refrigerants used in many applications. A new class of fluids called unsaturated hydrofluorocarbons or hydrofluoroolefins has been developed to address this concern. These new fluids are being blended with existing HFCs to obtain lower GWP replacements or substitutes for today’s refrigerants. This paper provides an overall assessment of the application of R513A, an azeotropic blend of R1234yf and R134a (56%wt/44%wt), as an alternative to R134a. R513A provides specific environmental and safety features of interest including: no impact to stratospheric ozone, 56% reduction in GWP compared to R134a, no significant secondary adverse environmental impacts, low toxicity and non-flammability. This paper reviews the thermodynamic cycle performance and heat transfer characteristics of R513A relative to R134a.

A major concern in the operation of cooling tower systems is the prevention of scale on heat transfer and evaporative surfaces. The process by which scale forms is not often clear or well explained, and the means by which scaling may be controlled is commonly not explained to any significant degree. This paper attempts to outline the mechanisms of scale formation, discuss chemically based and non-chemically based strategies for scale control, provide real-time instrumental data illustrating the effectiveness of both chemical and non-chemical control and then discuss the basic requirements for successful implementation of each strategy given the many chemical, physical and operational variables generally associated with cooling tower operation. Each strategy has its advantages and diadvantages and no one strategy is well suited under all circumstances. It is hoped that this paper will help clear up some of the misconceptions concerning chemical and non-chemical cooling water treatment and promote more meaningful and informed discussion during the treatment strategy selection process.

HVAC water systems (cooling tower/condenser water) are frequently operated without filtration—leading to reduced efficiency. Filtration selection for cooling tower water is accomplished by determining the type of solids present in the water, water quality requirements, physical space availability, weighing the pros and cons of the various filtration options and budget constraints. Selecting the wrong type of filtration is akin to taking vitamins for pain relief: good product but wrong application. This paper compares the differences between barrier and non-barrier filtration options and when to apply each option. Either type of filtration, when correctly applied, assists HVAC equipment to operate at design efficiency.

Awareness of non-chemical processes and the successes of various technological solutions to common water treatment problems are now well established. Despite detractors, non-chemical and physical water treatment products continue to make their mark by providing results that meet and exceed water treatment industry standards. Although initially propelled by the greening of the built environment, physical water treatment now stands as a viable alternative to traditional chemical programs. The debate over whether these technologies work is over, with the new discussions centered around when and how to apply them. With technological progress and continued innovation, these once-experimental technologies have given birth to experienced and proven methodologies. This paper covers the history of various technologies and examines the plusses and minuses of each class of non-chemical water treatment. It illustrates how the latest advancement improves on pulsed power and in combination with advanced suspended solids management provides unmatched savings of water and energy, while matching or exceeding the performance metrics of modern water treatment deliverables.

The debate continues between the use of non-chemical water treatment devices and chemical water treatment for treating cooling water systems. The goals of any cooling water treatment program are to protect against corrosion, deposition and microbiological fouling. This paper presents the chemical water treatment method to accomplish the best performance standards. In doing so, the authors critique both and highlight the benefits of chemical water treatment. The authors present results of trials where both technologies have been used to treat cooling water and discuss the methodologies behind each technology. Many providers promote “green,” “safe” and “economical” as the reason to use a certain technology. Many users select their appropriate method of treatment based on these same factors. What factors should determine the type of treatment? When we define success, we can determine the best method to achieve it.

Ambient particulate matter (PM) air pollution is critical to human health and well-being given the association of urban air pollution with increased respiratory and cardiovascular mortality. For urban office buildings in big cities, use of economizers has dramatically increased recently for energy saving and ventilation purposes. The objective of this paper is to examine outdoor-indoor transports of ozone and PM_2.5 (particles < 2.5 micron in diameter) for urban office buildings considering economizer operating modes. This study employs multi-zone contaminant transport model for prediction of outdoor-indoor pollutant dynamics in two cities: Los Angeles and Beijing. The model simulates an infiltration of ambient ozone, PM2.5 (< 2.5 micron), into a DOE reference building (medium office) based on outdoor climate condition, outdoor intake and filtration efficiency. Seasonal variations are also considered to capture the influences of high ozone levels during the summer in LA and elevated particle concentrations during the spring season in Beijing.

Exposure to ambient fine particles (PM_2.5: particles < 2.5 μm in diameter) and ultrafine particles (UFPs: particles < 100 nm in diameter) has adverse effects on human health. Residential buildings greatly impact human exposure to outdoor particles because people spend more than 90% of their time indoors (and much of that time at home) and outdoor particles can infiltrate through building envelopes and mechanical ventilation systems with varying efficiencies. This paper will model the impact of various combinations of central forced air HVAC filtration and mechanical ventilation systems on indoor concentrations of fine and ultrafine particles of outdoor origin in three types of residential buildings (i.e., older, existing and new homes).

Exposure to airborne particulate matter is connected with adverse human health effects. The majority of human exposure to airborne particles occurs inside buildings. In order to improve indoor air quality by reducing indoor particle concentrations, high efficiency particle filters installed in central forced air heating, ventilating and air-conditioning (HVAC) systems are being used. ASHRAE Standard 52.2 relies on a method of laboratory testing to measure the performance of general ventilation air-cleaning devices to assist end-users in their selection of appropriate air filtration products to increase living or working environmental quality. In this project, an in-situ test method is used to measure the particle removal efficiency of a wide range of commercially available filters in 28 particle size ranges from 0.01-10 µm in diameter.

Membrane-based energy recovery ventilators (ERV) are an effective means of reducing energy cost and allow for scaling down HVAC equipment. Owing to their compact geometry and rough surfaces of the porous membrane substrate, ERV exchanger cores can be fouled by airborne particulate matter. In this study, the influence of particulate fouling on the membrane-based ERVs was investigated via accelerated material- and core-level fouling experiments.  The core-level experiments, inside an aerosol wind tunnel (AWT), investigated the effect of dust accumulation on the performance of cross-flow cores (including sensible and latent effectiveness, and pressure drop) through comparing pre- and post-fouling performance tests of two core samples. The influence of the membrane surface exposed to particle-laden air, and working airflow rates were considered during AWT tests.

This paper introduces a systematic approach to define a lighting replacement strategy that comprises the following: lighting type, location, efficacy, cost and service classification. The paper also presents an actual life-cycle cost example as a decision support tool to evaluate replacement cost effectiveness. Study results highlight the significant role lighting replacement can play to meet target energy consumption and reductions in CO2 emissions. The approach proposed in this paper can be adopted by organizations operating under similar environments that want to showcase their leadership in energy efficiency and environmental compliance.

Climate has a major impact on energy use in buildings, especially in Saudi Arabia. Due to the complexities of the Saudi Building Code, Energy Conservation Requirements (SBC-601) and the lack of a simple building science-based climate zone map for Saudi Arabia, neither builders nor designers have been able to demonstrate code compliance, and neither have the authorities having jurisdiction been able to mandate code enforcement properly.  As a result, 70% of Saudi Arabian homes are today, for example, not insulated, which results in the consumption of nearly 52% of electrical power generated. This study explains the details of how the above-mentioned shortcomings can be addressed through development of a Kingdom-specific climate zone map online tool, which characterizes the SBC 601 minimum prescriptive energy efficiency performance requirements for residential and nonresidential buildings envelopes. The study also highlights the significant role this tool can play in facilitating code compliance and gives examples of the potential energy savings.

ASHRAE 90.1 is an energy standard for buildings except low-rise residential buildings. It provides minimum design and construction requirements for most types of Residential and Commercial buildings and their systems. The objective of this technical paper is to analyze and assess, some of the building envelope values in ASHRAE 90.1 such as wall, roof, and glazing, using building energy modelling simulation techniques for different regions in the Middle East. A comparative analysis is made for thermal conductivity (U) values of walls, roof,  glazing, and solar heat gain coefficient (SHGC), based on the results from building energy modelling simulation, to analyse the energy consumption and energy savings potential and obtain optimised values for these parameters relevant to the Middle Eastern region. Also, a comparative analysis is made to examine the performance of building envelope values with Residential and Commercial buildings.

The energy utilization index (EUI) is commonly used to describe a building's energy performance. This index is not without shortcomings, as it does not adequately address issues such as space utilization, occupant density, or irreducible process loads. This paper explores the use of a bottom-up approach for energy benchmarking, both for design optimization and portfolio analysis, utilizing a concept known as energy usage effectiveness (EUE). The EUE metric is based on the ratio of a building's total energy use divided by an adapted calculation of process energy use. Benchmark EUE values will be calculated based on the Department of Energy's Commercial Reference Building's for new construction, existing buildings "post-1980" and existing buildings "pre-1980s." The full range of ASHRAE climate ones will be represented for all of the major building types available. EUE will be compared to calculated EUI, to highlight correlations and divergences in the outcome data. The EUE concept will also be applied to data from a heavily sub-metered high-performance building, as well as public data published in ASHRAE high-performance building case studies. Discussion will include possible ways for ASHRAE Standard 90.1 to be adapted to utilize EUE and further rolled into green construction codes.

The energy use-related effects of ultraviolet germicidal irradiation (UVGI) to mitigate biological fouling (biofouling) of a chilled water cooling coil are investigated via a field study. A visibly bio-fouled cooling coil in an air-handling unit serving an operational building in a hot, humid climate is monitored for 5 months to establish a fouled coil baseline. Parameters monitored include air flow rate, airside pressure drop, air temperature and humidity upstream and downstream of the coil, chilled water flow rate, entering and leaving chilled water temperature and waterside pressure drop. A UVGI coil irradiation system is installed on the downstream side of the coil following typical manufacturer guidelines, and the system is then passively monitored over a period of 10 months. An average improvement of 5.2% to 7.9% in coil airside pressure drop, and 11.9% to 12.7% in heat transfer coefficient (both 95% confidence interval) are estimated by comparing data from the baseline and post-irradiation periods. Complexities of the physical phenomena involved, e.g. the effect of both airflow and latent load on airside pressure drop, are taken into account.

The goal of this project was to assess the potential benefits of using a highly-controlled surface wettability to preferentially condense (and therefore locate) water droplets on a heat transfer surface during the early stages of frost growth to affect the thermophysical properties of the frost layer (i.e. density, thermal conductivity, etc.). It was postulated that a thinner, denser frost layer might lead to improved heat conduction (and therefore improved air-side heat tranfer) and longer operational periods before defrosting becomes necessary. The retention of less water on the heat transfer surface following defrosting might also be used to slow frost growth in the subsequent cycle and therefore lengthen the operational cycle. Thus, accompanying this objective was the goal of creating heat transfer surfaces that more completely drain the melted frost layer during an applied defrost cycle.

It has been noticed by many users that whenever a germicidal UV disinfection is performed in a room, there is often a strange odor left behind. It is not ozone, which can be easily identified and measured. It is more like a slightly pungent smell. It's actually easier to acknowledge the smell than to describe it. Until now, no satisfactory scientific explanation about the origin of this peculiar odor has been provided. In this paper, the authors provide a clear explanation of the source of this odor. Evidences show that the root cause seems to be the interaction of UV with airborne dust.

A number of studies reported associations between ground-level ozone and various adverse health effects, including respiratory and cardiovascular diseases. Indoor ozone is also a significant initiator of indoor chemistry by driving various oxidative processes which produce many harmful oxidation products. Hence ozone is the required challenge gas with respect to oxidizing gases to be tested in AHSRAE Standard 145.2-2011. In practical application, how often the filters should be changed on specific operation condition is a key question. Wheeler-Jonas equation is widely used for describing breakthrough curves of VOCs removal by granular activated carbon (GAC).  This paper will investigate the applicability of W-J equation to the oxidizing gas - ozone. The experiments will be conducted on a state-of-the-art full-scale filter test rig. The air tightness, uniform distribution of challenge gases and stable temperature and humidity control of the test rig have already been validated. Commercially available AC filters with different pore sizes, specific areas and bulk densities will be tested.

Institutional campuses often times encompass both centralized and decentralized heating and cooling systems. Each configuration inherently has advantages and challenges when trying to maintain occupant comfort while minimizing energy consumption.  Recent technological advancements in computing power allows building energy modelers to quickly and efficiently develop models which can be evaluated as part of a centralized plant or as a stand alone system.

ASHRAE is aiming for buildings to achieve net-zero energy use, including energy-intensive mission critical facilities, by the year 2030.  The design methods to achieve this goal are aiming to be in place in less than 5 years, by 2020. There is a need to ensure designers can choose the most beneficial options available.  Often data center heat is considered a bane, and water source energy recovery is not an option because the heat rejection and distribution is limited by physical, monetary and temperature aspects.  However, opportunities are becoming more available for new and existing facilities as data center densities and water cooling temperatures move steadily higher. This paper reviews the potential benefits of operating with higher water temperatures and finding means to couple alternative systems as heat sinks for modern data centers.

Data centers have an extensive range of complicated system design choices, which can often times seem overwhelming when deciding the best way to maximize the system design for reliability and energy efficiency. Is an air-side or water-side economizer system better, or should an indirect system be used over a wet-bulb economizer design? Is the industry moving away from raised floor designs to installing server cabinets directly on slab? High-level decisions can be complicated, but diving further into the details reveals even further trade-offs and directions in designs. Should containment be done on the cold-aisle or hot-aisle? Is it better to select units with EC fans or VFD equipped motors? The authors present a range of topics for debate in data center design and discuss the strengths and weaknesses of each, applicability and limiting factors as well as encourage participation in discussions about highly contested topics in the data center industry. These debates are happening right now across designers and operators, end users and owners and produces a variety of viewpoints and engaging discussions on complex systems design.

The as-installed energy efficiency of unitary systems is much less than that of central systems, and the efficiency gap widens as systems age due to maintainability issues.  Energy engineers and service technicians use indirect indicators of equipment performance and make adjustments according to manufacturer guidelines and standard field practice, which varies with technicians’ level of experience.  Growing numbers of unitary systems combined with shrinking budgets result in deferred maintenance, and long-term operation of equipment at degraded levels. Energy efficiency is a metric that must be measured to be optimized.  This paper reports on field testing of continuous sensing of actual operating energy efficiency to control unitary equipment operating parameters, provide remote fault detection diagnostics and support maintainability. The energy efficiency of most unitary HVAC systems is much less than chilled water systems and limited cost-effective choices exist for increasing their energy efficiency.

In the U.S., there are 14.4 M electric-heated dwellings using 0.16 quad/year for heating in cold regions, e.g. ASHRAE climate regions IV and V. Conventional air-source heat pumps (ASHP) do not work well in such cold zones, due to high compressor discharge temperatures, large pressure ratios and inadequate heating capacities at low ambient temperatures. Consequently, noticeable portion of auxiliary strip heating has to be used to meet the building heating load. Two options of tandem compressors were studied, with one using two identical, single-speed compressors, and the other using two identical, vapor-injection compressors. The system modeling and laboratory testing results will be presented in the paper.

A 250 m², two story, residential home of the style typical of the Gaithersburg, Maryland area was constructed in 2012 to illustrate technologies employed to produce a netzero energy home. It functions as a laboratory to support the development and adoption of cost-effective NZE designs, technologies, construction methods, and building codes. The primary design goal was to meet the comfort and functional needs of the simulated occupants. The first annual test period began on July 1, 2013 and ended June 30, 2014. During this period the heating and air conditioning of the home was performed by a novel air-source heat pump that utilized a reheat heat exchanger to allow hot compressor discharge gas to reheat the supply air during a dedicated dehumidification mode.

The application of vapor injection to the compression process leads to a decrease in discharge temperature, extending the operating envelope to lower suction pressures. Additionally, it increases the coefficient of performance as well as the heating capacity under these conditions. Vapor injected compressors are therefore ideally suited for cold climate heat pump applications. This paper introduces a PI-type mapping of a dual port vapor injected compressor’s performance data trained with data from both, in-system testing as well as test-stand testing.  The in-system testing was conducted in a prototype cold climate heat pump, where injection mass flowrates and suction superheat were a result of the operating conditions.  In contrast, suction superheat of the test-stand data was fixed while injection flowrates were dictated by the test plan. These differences result in limitations of the mappings if the model is trained with only one of these sets.

Vapor injected compressors are one of the promising technologies for cold climate heat pumps because it enables compressor operation with a large range of evaporating temperatures at acceptable efficiency. However, the large operating range also makes it difficult to generate empirical maps that are applicable to most of its operating conditions. This paper discusses a method to create an empirical map using the Buckingham-PI theorem and estimates the resulting extrapolation uncertainty. Data from the laboratory testing of a cold climate heat pump were used to generate the map. The uncertainties from model random error and training data were calculated to examine if the model is reliable at extrapolation.

Ground source heat pump (GSHP) systems are commonly used in Sweden for both residential and commercial buildings.  However, there are several key differences with GSHP systems utilized in the USA. Scandinavian systems are often heating-only, and instead of using grouted boreholes, groundwater-filled boreholes are often used.  These boreholes are cased from the ground surface to the usually-shallow bedrock.  A single or double U-tube is commonly suspended in the borehole.  These boreholes are often deeper than those commonly used in the USA.  This paper reviews current Scandinavian practice for borehole design and discusses several installations with boreholes 250 – 300 m (820-984 ft) deep or deeper.

The purpose of this paper is to explore the performance of shallow depth helical heat exchangers coupled with ground source heat pumps (GSHP) for residential HVAC applications.  This shallow depth system serves as an alternative to traditional vertical bore fields, which carry high installation costs.  These helical heat exchangers occupy considerably less land when compared to horizontal configurations, but are still influenced by changing ground temperatures driven by seasonal weather conditions.  Performance data and design information is limited for helical heat exchangers, which has limited their adoption amongst GSHP system designers and installers.  In Situ testing was performed for a GSHP system to provide designers with performance information and insight towards appropriate applications of this technology.

Heat pumps use less energy when the difference between the source and load temperatures is small. For a ground-source heat pump (GSHP), the source temperature is prescribed by the local ground temperature. As for the load temperature, it depends on the type of heating system. In this paper, the performance of a water-to-water heat pump coupled to two different heating systems is examined. The first one is a radiant type floor heating system operating at a relative low temperature (≈30 °C). The second system uses a fan-coil unit operating at higher temperature (≈45 °C) to supply space heat. The objective of the paper is to quantify the energy savings from running a GSHP at a low load temperatures.

Photovoltaic panels that provide electricity and thermal energy are now commercially available. These PV/T collectors use either the air or a liquid as the heat transfer fluid to collect thermal energy. This paper examines the overall system performance of PV/T collectors linked to a ground-source heat pump equipped with a four-pipe borehole. The system selected for this study consists of two independent fluid circuits. In the first circuit, the outlet fluid from a liquid-cooled PV/T collector is first pumped through a heat exchanger then to the ground heat exchanger. In the second circuit, fluid is pumped from the ground heat exchanger to the heat pump via the heat exchanger which provides a thermal link between the PV/T and GSHP circuits.

Studies have shown that neglecting borehole thermal capacity in annual simulations of ground-source heat pump systems can lead to an overestimation of the energy consumption by 3-4% when the heat pump is operating intermittently. There are various approaches to account for thermal capacity when simulating geothermal boreholes. The objective of this paper is to validate the TRCM procedure. Experimental data from two tests performed at the Canadian Centre for Housing Technology (Ottawa, Canada) are used for this validation.

This paper refers to a study on the application of the thermodynamic analysis method proposed by
POPPE to model the thermodynamic behavior of countercurrent water cooling towers, to improve
performance. This method replaces the traditional method used today, more simple and less accurate, proposed by
MERKEL. The objective is to produce a mathematical routine using this method, to be used in supervisory systems in order to optimize the operation of these towers, looking at energy savings.

Early stage design has fundamental impact on building performance as they place significant limits on later design options. The objective of this study was to develop a simplified and scalable approach for optimizing the form, massing and orientation in early design stage. In this approach, a reference building was first defined with pre-selected building materials and assemblies and HVAC system for the intended climate and site conditions. The energy performance of this reference building was estimated by whole building energy simulation such as EnergyPlus at the same time. Heat fluxes and irradiation fluxes received by these interior surfaces of enclosure were also extracted from the reference building simulation.

This paper is about the application of Mixed Methods for design professionals and social science researchers.   The purpose is to describe an intellectual commons which integrates qualitative and quantitative data related to sustainable design and operation of the built environment. Once described, the proposed intellectual commons would include a form of communication based on data described by symbolism and logic to be shared by the broad range of worldviews in our global society. This form of communication models that which is common in the process of problem solving for many academic and professional disciplines.

Designing energy efficient buildings has been traditionally viewed as an optimization problem with a few stipulated constraints which could be tackled by mathematical methods relying on detailed computer simulations. Recently it has been argued that the conceptual building design process should inherently and explicitly contain an interactive process which captures the synergy between automated performance prediction with the human capabilities to perceive, evaluate and ultimately select one (or a few) suitable solution(s). The need to address multi-criteria requirements makes it even more valuable for a designer to know the “latitude” or “degrees of freedom” he/she has in changing certain design variables while achieving preset criteria such as energy performance, life cycle cost, environmental impacts, etc.

Heat losses and gains through opaque building envelopes (such as walls, roofs and floors) significantly affect the overall energy consumption of buildings. To reduce energy consumption of buildings, it is important to ensure that building envelopes exhibit excellent thermal insulation performance. However, the actual insulation performance of building envelopes varies depending on components and construction methods even if the same insulations of equal thickness are used. Therefore, this study aims to evaluate thermal insulation performances of various opaque building envelopes considering thermal bridges and to discuss methods of reducing thermal bridges.

From the late 1940's to the late 1960's, significant efforts were made by ASHVE and ASHRAE to evaluate and quantify the impact of window shading. In the context of the now defunct Shading Coefficient (SC), well known researchers such as Parmelee, Ozisik, Schutrum, Farber, Yellott and Keyes laid the groundwork for much of the work that followed decades later. Of particular interest are the efforts of Keyes, published by ASHRAE in 1967. In that work, he presented measurements of the solar-optical properties of fabrics determined using a custom made apparatus. The main contribution of this work was a method of classifying fabric properties based either on visible inspection, or property measurements. The result was the Keyes Universal Chart, which has been in the Fenestration Chapter of the ASHRAE Handbook of Fundamentals since the 1970's.

The single-family residential building stock in California is dominated by gas-fired storage water heaters. This is a result of the building energy efficieny code. For decades the water heater energy consumption calculated in the budget compliance tools has made it very hard to justify using an electric resistance water heater. As a result very few electric water heaters have been installed. The compliance tools were written in a way that poorly calculates the hot water load. Furthermore the calculated time of energy use by water heaters does not account for the buffering effect of a storage tank. An important part of the budget calculation uses a time dependent valuation of electrical generation to capture the societal costs of using electricity for every hour of a typical year. This has meant that the actual effects of the time difference between the hot water use and the energy consumption of electric storage water heaters are not being evaluated properly. The combined effect of these oversights has inadvertently effectively blocked the adoption of heat pump water heaters in new construction in California. This presents a major obstacle for reaching the state's net-zero energy and greenhouse gas emission targets. This paper describes the way the building energy efficiency code currently calculates the water heater energy budget. Problems in the calculation procedure are explained. Our knowledge about residential hot water systems has increased greatly in recent years. These research efforts have significantly improved our ability to characterize these systems. Revisions to the building code calculations are suggested based on this increased knowledge. An enhanced hot water load calculator has recently been adopted by RESNET. Detailed field studies over the past several years of residential hot water draw patterns provide a source for more realistic draw schedules to use in the calculations. An open source water heat simulation model developed for utility incentive programs in the Northwest could be adapted to calculate the amount and timing of energy use. The role of demand response controls to reduce the impact of electric heat pump water heaters on the grid are also discussed.

The purpose of this paper is to study the energy impact of operating a HPWH in the basement of an R-2000 equivalent house, i.e. the Canadian Centre for Housing Technology (CCHT) twin house test facility, located in Ottawa Canada. We included four key parameters in the study: Did the operation of the HPWH have any adverse impacts on the basement air temperature? Was the HPWH operating more efficiently than the baseline water heaters? What if any were the impacts on energy consumption during the heating and cooling seasons and were there energy cost savings during the Heating and Cooling Seasons?

In the effort to achieve net-zero operation of residential buildings, advanced water heating technologies are vitally important.  Solar thermal is the most cost and energy efficient, renewable energy alternative for water heating, but the use of electric resistance as the backup to solar thermal may no longer be the most suitable option. This paper explores the year-long performance of a 189 liter (50 gallon) heat pump water heater (HPWH) serving as an auxiliary unit to an active indirect solar thermal water heater with a 303 liter (80 gallon) storage tank in a net-zero energy test home at the National Institute of Standards and Technology, Gaithersburg campus.

Approximately half of water heaters sold in the U.S. and Canada for residential applications are natural gas fired storage water heaters, and for these products the maximum steady state thermal efficiency of available products is approximately 96%, with transient rated efficiencies much lower.  To move beyond the thermal efficiency limits of standard condensing-efficiency residential gas water heating equipment, this paper describes an effort to develop an economic gas-fired ammonia-water absorption heat pump deployed as a packaged storage water heater.

Radiant cooling and heating systems can potentially provide significant energy savings, possible peak load reduction, and better thermal comfort for the occupants. Such systems primarily depend on the radiant mode, instead of convective mode, for the transfer of heat within a space. These systems are often required to supply ventilation air to maintain certain indoor air quality and humidity in the space. The air flow patterns of the supply air and resulting buoyant airflows in the space can affect the performance of radiant systems. The flow rate and temperature of the supply air; location and type of supply air diffusers; and strength and location of interior sensible heat loads can affect the relative share of radiative and convective heat transfer in the space. This paper with the help of Computational Fluid Dynamics (CFD) analysis will evaluate the impact of various parameters of the supply air including the supply airflow rate, supply air temperature, and location and type of diffusers on the operation of radiant systems.

Between 1990 - 2006 the energy use of the ventilation systems in Swedish schools has doubled. This is mainly due to an increase of cooling demand which results in higher air-flow rates. In recent years many schools changed from displacement ventilation (DV) to mixing ventilation (MV), because MV causes fewer problems with thermal discomfort, although DV has higher ventilation efficiency. Studies show that 87% of Swedish schools use constant air volume (CAV) and it’s estimated that a change to variable air volume (VAV) could save 0.12-0.33 TWh per year. Therefore the aim of this study is to investigate whether it’s possible to replace DV with MV to create a comfortable indoor climate in a typical classroom and at the same time decrease the energy use by using VAV and Low Pressure Drop Ceiling Supply Device (LPDCSD).

This paper introduces a new model to simulate the energy performance of VRF systems in heat pump operation mode (either cooling or heating is provided but not simultaneously). The main features of the new model are the introduction of separate curves for capacities and power inputs of indoor and outdoor units instead of overall curves for the entire system, the allowing of variable evaporating and condensing temperatures in the indoor and outdoor units, and variable fan speed based on the temperature and zone load in the indoor unit. These features enhance the accuracy of the estimation of VRF system performance in both heating and cooling modes, especially during low part load operations.

The variable refrigerant flow (VRF) technology provides multi-split ductless configurations that typically use one outdoor unit (ODU) and multiple indoor units (IDU). VRF systems offer many advantages, such as elimination of duct loss of air distribution, design and installation flexibility, compactness, integrated controls, quiet operation and reduced maintenance cost. Also, multi-functional VRF (MFVRF) systems have achieved remarkable development, offering flexible operation of individualized zoning control, i.e. making possible simultaneous heating and cooling in addition to cooling or heating only modes. Meanwhile, such flexibility further complicates the operation and control due to diversified system configurations and highly variable operational loads. This paper proposes extremum seeking control (ESC) schemes for MFVRF system under different operational modes, in order to maximize the efficiency provided the satisfaction of thermal comfort.

Building energy systems often consume in excess of 20% more electrical energy than was the design intent largely because of equipment performance degradation (e.g. filter or heat exchanger fouling), equipment failures, or detrimental interactions among subsystems such as cooling and then reheating of conditioned air. Identifying the root causes of efficiency losses is challenging because a gradual erosion of performance can be difficult to detect.  This paper is focusing on the faults that are implemented using OpenStudio measures. These measures are created in OpenStudio Application or the Parametric Analysis Tool, which are written in Ruby scripts. These faults related measures act like add-on marco to make changes to the energy model to reflect faults.

Some HVAC engineers and designers are uncertain of the requirements for fire dampers and smoke dampers, especially with regard to the difference between partition types, because those requirements are typically found in the model building codes rather than the model mechanical codes. Some play it safe and specify fire and smoke dampers where they really are not necessary. This conference paper presents a fire and smoke damper summary for HVAC engineers and designers based on the model building codes. Topics addressed include the differences between fire walls, fire barriers, shaft enclosures, and fire partitions and between a smoke barrier and smoke partition, so that one can properly apply (or not apply) fire and smoke dampers where they are required and only where required. Eight helpful design tips are included. This paper is intended as a good introduction to the topic for less experienced engineers or designers; and a good review for the more experienced.

The use of trend data from Building Energy Management Systems (BEMS) is a cost-effective solution to provide the necessary data for the ongoing commissioning. This paper presents the use of trend data, recorded every 15 minutes, with a virtual air flow meter for the estimation of the outdoor air flow rate brought in the air-handling units. A virtual flow meter estimates the value of a physical variable in the heating, ventilating and air-conditioning system where a physical sensor does not exist. For this purpose, a mathematical model is used along with measurements from available sensors in the system. In this study, a virtual air flow meter was developed to estimate the outdoor air intake, and the results were presented as the ratio α of the outdoor air flow rate to the supply air flow rate.

Buildings are maintained at slightly positive pressure by the air handling units to avoid infiltration of unconditioned air. The conventional AHUs rely either on direct building pressure control or volume tracking control with a single loop proportional integral derivative controller to maintain positive building pressure. Even though this type of control structure is simplistic, the performance is usually not satisfactory. The purpose of this paper is to evaluate the performance of the cascade control on the building static pressure in comparison with the two conventional controls by simulation. An airflow model of an AHU system with PID controllers is developed. Performance of the two conventional controls as well as cascade control is simulated and subjected to wind effect, pressure fluctuations and flow sensor error.  The simulations conclude that the cascade control method stabilizes the control signal and compensates the error in flow measurement.

Wind driven roof ventilators have been in existence for over 3 decades. Developed in the USA, where it is primarily used as an attic /domestic ventilator, the roof ventilators have found a more industrial application in India considering the higher throat dia and material of construction. Evaporative cooling systems can be used for cooling at a fraction of the cost of conventional air conditioning systems. If used in a correct manner its ideal for sustainable and energy efficient comfort as well as process conditioning requirements. The ECS used for the case studies in this paper are systems that deliver higher air volume with lower energy consumption. Fabric Air Dispersion Systems were used for their lower carbon footprint and the fact that they can be removed and cleaned. Combining a precise ECS with WRV and using fabric ducts for delivery, an energy efficient system can be designed with perfect air balancing, optimum airflow patterns and utmost effectiveness to provide the necessary conditions in all parts of the building.

Advancements in computer technologies have made it economical for HVAC equipment manufacturers to implement computational fluid dynamics (CFD) in order to aid in the design process. The benefits of using CFD analysis include reducing the amount of time to optimize a given design, ease of identifying potential failure points in existing products, and reducing the number of laboratory experiments required. CFD offers the ability to visually characterize the airflow and heat transfer through an AHU and assess uniformity as it enters the heat exchanger. This paper presents the CFD models used to characterize the airflow uniformity in order to increase the overall heat exchanger efficiency in an AHU.

The residential building sector is responsible for about 26% of total energy consumption in the European Union and account for 75% of the total building stock. About 64% of the residential buildings were constructed before the 80s and the widespread adoption of energy efficiency regulations. In the framework of a European research project there is an ongoing multinational effort to develop a conceptual framework for monitoring the effectiveness of energy efficiency measures (EEMs) applied in European residential buildings. The conceptual framework is based on national residential building typologies for single- and multi-family houses. The goal is to derive suitable energy performance indicators that will enable stakeholders on different scales to ensure a high quality of energy refurbishment plans, check compliance with regulations, track and steer the refurbishment processes in a cost-effective way and quantify actual energy savings in order to meet regional or national targets. This paper will provide an overview of these efforts and focus on the results from the Hellenic pilot action within EPICOPE.

Advancements in whole building energy modeling have coincided with the demand for improved building energy performance and have become a useful tool in determining optimal configurations of energy saving measures on the path to net zero building. This study presents a multi-objective optimization environment in which passive energy conservations measures of a high performance house in Toronto are evaluated for life cycle cost and performance. The main objective of the study was to identify economically efficient design solutions that may be used to inform future efficient housing design and housing performance standards.

Recently built residential apartment buildings have faced the issue of increased condensation risk caused by highly insulated and airtight building designs used to decrease building energy consumption. In particular, glazing systems have a high risk of condensation on the inside surface of building envelopes. Especially during cold winters in Korea, condensation in residential buildings damages the interior surfaces, leading to mold or mildew problems and causing discomfort of the building occupants. To eliminate condensation risks and secure the well-being of the occupants, the Korean Design Standard for Preventing Condensation was announced in 2014. Nonetheless, current glazing systems in the market cannot fulfill the strengthened design standards. Therefore, a high-performance glazing system that satisfies the new enhanced standard is needed. A brief comparison between the newly developed Korean Design Standard for Preventing Condensation and other international standards was performed.

This paper discusses how the use of advanced engineering tools in HVAC industry has increased as the cost of computational fluid dynamics (CFD) has become more affordable for engineering firms.  We employed CFD in a design-build project in which conventional engineering tools were not sufficient to address the design challenges of developing an efficient chilled water thermal storage system. The system utilized a series of vertical tanks to store chilled water to supplement chillers in the event of a power failure. Chilled water is routed from the storage tanks to critical equipment during chiller re-start, bridging the gap in time that the chillers are unable to provide set-point chilled water due to power failure and subsequent required time to re-start.

As air conditioning (AC) has evolved from luxury to almost necessity, the rapid uptake of residential AC systems is creating major problems for our electricity network infrastructure, particularly on peak summer days. By using automated demand response (DR) signals, energy service providers aim to constrain the electrical demand that these systems place on the network. One such DR signalling scheme is Australian Standard 4755.3.1 that defines how air conditioning appliances respond to a set of initiating signals for reducing energy consumption. This paper highlights potential benefits obtained when performing ‘pre-cooling’ control strategies in summer prior to a demand response event.

Smart windows are used to reduce energy consumption and improve thermal and visual comfort by controlling the solar flux entering into a building and/or adapting their thermal resistances. A commercial building with integrated electrochromic windows is modeled. The hour-by-hour state of the smart windows required to minimize overall energy consumption (heating, cooling, lighting) while respecting constraints related to visual comfort is determined through an optimization strategy based on genetic algorithms. Then, this optimal control is compared to two other approaches that could be applied in real-time applications: (i) rule-based control, and (ii) predictive control. The impacts of thermal mass, façade orientation and climate are analyzed.

Accurate energy performance prediction of HVAC system plays a significant role for intelligent building operations to improve energy efficiency and reduce energy consumption in buildings. In modern commercial and residential buildings, large amounts of raw data, including electric metering data, are monitored, trended and saved in, for example, Building Automation System (BAS). Due to the complexity of building mechanical and electrical system and the cost, practically speaking, it is impossible to have sensors/meters to monitor the building at a fine granularity. Building total energy consumption (e.g., total electricity consumption) is one of the most commonly available metering data.

Many facility departments have installed energy meters seeking to pin point how, where and when energy is being inefficiently utilized. This has led to the recording of vast amount of data over extended periods of time, which makes it very difficult to manage and manually analyze. Luckily, techniques in machine learning have shown promising results in automated knowledge discovery making it more and more crucial when large data is at hand. This paper applies machine learning (ML) algorithms to detect abnormalities in chilled water systems (CWS) at building level. Two abnormal situations are pursued: chilled water sensor misreadings and low thermal efficiency in terms of delta T. The visualization of building chilled water historical data provides general trends and an initial identification of the building abnormalities; this visualization also helps to lay down the requirements for the abnormality detection algorithms, and eventually, their selection.

The accuracy of experimental results has always concerned engineers and scientists. The uncertainty of each parameter is desired to be minimized because these uncertainties will propagate in the data reduction process. In heat-transfer equipment testing, there are usually two independent measurements of heat-transfer rate in the hot and cold stream respectively (Q_h and Q_c). It is proposed in this paper that Q_ave should be calculated based on a form of weighted-linear average, with weighting factors depending on the individual uncertainties in Q_h and Q_c. Heat-transfer rate which has higher uncertainty will be weighed less in the average, and the other one with lower uncertainty will be weighed more accordingly. Implementing this new methodology will minimize the uncertainty in heat-transfer coefficient and Colburn j factors, which will consequently provide more accurate data for use in the development of correlations or for performance comparison purposes.

The currently developing concept of net zero energy building should be adaptive for different climate situations. Buildings in the severe cold area of China have higher energy consumption and release gas emission due to large heating energy demand in wintertime. It is challenging to design and operate a net zero energy building in severe cold climate. This paper will discuss the feasibility of a net zero energy office building design targeting for energy efficiency and environmental sustainability from the initial planning, final construction, until the operation. An on-campus office building is studied as an experimental objective in Shenyang, Liaoning Province in China.

The global demand for electrical energy is increasing as a result of population growth and a higher standard of living that is enjoyed by many people.  However, the availability of electricity is often limited by fuel supplies and/or infrastructure for generating and distributing power.  In addition, the looming threat of green house gas emissions and the collateral damage to the environment has encouraged efforts to diversify methods of electricity production.  These factors have led to the increased use of renewable energy, particularly solar and wind, to help meet the demand for energy. In particular, the shift towards solar energy has been accelerating due to the decreasing cost of materials and installation. Universities are one possible location where solar electricity makes good sense.

As zero net energy (ZNE) buildings and other low-energy buildings become increasingly common it is important to consider how different ZNE strategies can interact with their local electricity grids. Demand response technologies and grid-sensitive design features in ZNE buildings will be critical to enabling the integration of these facilities into the grid at a large scale. The paper describes three tiers of DR and renewable energy technology integration in commercial buildings: Conventional buildings with one-way energy flows or conventional net metering. Moderately responsive buildings with interactive demand response capacity. Fully grid-integrated buildings with active and passive efficiency and demand response features, often with on-site renewable energy. This paper presents a framework for employing design strategies and measures that ensure buildings of the future can benefit from, and support, the grid modernization efforts that will occur throughout the life of the buildings.

The path towards zero energy buildings is fraught with many challenges, the onsite renewable energy production to drive consumer appliances that are not low or zero energy is an important challenge. Therefore, developing the energy production such that the production mode is matched to the usage is the simplest manner to improve efficiency.  As such, energy consumption for lighting could be significantly reduced by optimizing the building`s design to maximize direct daylight usage, similarly cooking using solar stoves, or water heating using solar geysers, reduce the need for PV cells electricity. The most important energy consumption in most buildings is HVAC (which accounts for approximately 40% of a building`s energy consumption) which can be addressed with the use of a solar power absorption chiller. This article introduces a design of a novel solar concentrated photovoltaic thermal (CPVT) system that produces electricity and thermal energy simultaneously from the same surface area.