One of the primary noise transmission paths in buildings is from HVAC equipment through ventilation ducts. The ASHRAE Handbook provides tables for estimating the attenuation of lined and unlined ducts up to 10 ft (3.05 m) in length. The aim of this research is to suggest and validate a finite element approach to determine the attenuation of ducts of any length and dimension. The approach detailed simulates the standard measurement approaches for assessing duct attenuation. The duct air space, including the source and termination, is modeled using acoustic finite elements. Poroelastic finite elements are used to simulate the fiber lining, and the metal ductwork is modeled using structural finite elements. The model is used to determine the insertion and transmission loss of unlined and lined ducts. Predicted results are compared to measurement with good agreement.

The primary path of noise propagation in buildings is airborne transmission from building equipment through ducts. Attenuation is increased if elbows or side branches are introduced into a duct. In a companion paper, finite element analysis was used to predict the insertion loss of straight lined and unlined ducts and results were validated with measurement. In this work, finite element analysis is used to predict the attenuation of elbows and side branches. Results for elbows and branches are compared to the ASHRAE Handbook with good agreement. In addition, an important secondary noise transmission path is through duct walls into rooms. This path, which is often termed breakout noise, is also investigated using the finite element approach and results are correlated with an analytical solution and the ASHRAE Handbook with good agreement. Of note, it is demonstrated that the breakout transmission loss is much less than the insertion loss through lined rectangular ducts at some frequencies. This suggests that breakout noise may be the dominant noise path at some frequencies.

As a result of numerous pilot projects conducted all over the world, it was demonstrated that energy use reduction in commercial and public buildings can been reduced by more than 50% after renovation, and that some renovated buildings have met the Passive House Institute energy efficiency standard or even Net Zero energy state [1].  This paper summarizes the results of these studies. To evaluate cost effectiveness of deep energy retrofit (DER) using “core technologies” bundle, compared to typical building renovation based on minimum energy requirements, the paper proposes the use of net present value (NPV) of the difference in energy savings to estimate the budget increase limit. Since most of parameters required for LCC analysis differ not only by the individual country but also within the country (first costs and labor rates, energy rates, life of the project, inflation and discount rates, etc.), the concept of Scalar Ratio [8] is used to calculate limitations in renovation budget increase.

This paper presents the results of computational modeling analysis conducted by the U.S. Army Engineer Research and Development Center team of two categories of buildings with relatively low internal loads in 15 U.S. climates using the Net Zero Planner tool. This tool enabled simultaneous simulation of multiple building types and multiple technology bundles of energy efficiency measures in different climate zones. This research supported development of requirements for building envelope characteristics for DER projects. Information presented in the paper along with results of similar studies conducted in Denmark, Estonia, Austria, Germany, China, and UK [2,3,4] for their nation-specific climate conditions have been used to develop general guidelines for technology bundles to be used in DER projects [5].

International Energy Agency’s Energy in Buildings and Communities Program Annex 61 focuses on developing and demonstrating financial and technical concepts for deep energy retrofits of public buildings. A first and important step to define the methodology is to examine the economic aspects of deep energy retrofits in each of the participating countries. Estonia, Germany, Canada, Austria and Denmark have conducted a series of simulations in order to determine the economic conditions in the renovation of a pre- 1980s building. The analysis shows how deep renovation solutions and economic conditions differ from country to country and emphasizes the individual economic challenges of deep energy renovation. The analysis will be used in developing and demonstrating new and alternative funding mechanisms for a deep renovation project. This paper describes results for northern Europe, i.e. Estonia and Denmark.

Within EBC Annex 61: Business and Technical Concepts for Deep Energy Retrofit of Public Buildings are developed to increase pace and quality of DER projects in the public sector. Subtask A targets is to assess accomplished DER projects to define find optimized bundles both from energy efficiency and economical perspective in each of the participating countries. Based on general assumptions defined by the Annex 61 team, modeling studies for different types of buildings and different climate zones have been done. The paper describes the base lining and modeling process, the economic assumptions made for energy prizes, maintenance and other operating costs and consider the investment costs, the cost optimization process and the carbon footprint of the scenarios. The measure bundles resulting from the modeling are described.

The cooling performance of a raised-floor data center is dominated by its ability to deliver adequate cooling airflow to IT equipment through perforated tiles. Although many studies have focused on the design of plenum systems and the use of Computational Fluid Dynamics to predict tile airflow rates, very little has been published regarding accurately measuring airflows in existing facilities. We investigate the ability of a commercially-available passive flow hood to accurately measure data center tile airflow.

Energy efficiency has become increasing important in the data center industry, driven by rising energy prices, environmental legislation, corporate social responsibility pressures and competition. Energy efficiency is part of sustainability, however consideration of other aspects such as the embodied environmental impact of materials, components and systems are needed for a holistic view of sustainability. Life cycle assessment areas of protection may be defined as climate change, ecosystem quality, human health and resource depletion. The industry is starting to become more aware of these issues and developing metrics to quantify performance. This paper describes key data center sustainability issues and proposes how the industry should approach its environmental responsibilities in order to capitalize on the business opportunity as well as demonstrating sustainable leadership.

The required length of vertical ground heat exchangers (GHX) used in ground-coupled heat pump (GCHP) systems is determined to make the outlet temperature from the GHX remains within certain limits at peak ground load conditions. These conditions may not necessarily occur after 10 or 20 years of operation and often occur during the first year of operation. The primary objective of this paper is to develop a general methodology, using the framework of the ASHRAE bore field sizing method, for the calculation of the total required bore field length on a monthly basis during the first year of operation.

District cooling plants using large electric powered water-cooled vapor compression machines in warm weather regions are gaining popularity. Providing an economic mass scale cooling for buildings. This paper proposes to replace such a system with the use of direct-fired two-stage absorption chillers located at the power generation plant. Absorbers energized by the exhaust of a gas turbine power generation plant can be used to provide chilled water to cool nearby buildings. Calculations presented in this document can be used to analyze the feasibility of such an investment.

Liquid to air membrane energy exchangers (LAMEEs) are used to transfer heat and moisture between air and desiccant solution streams. LAMEEs use semi permeable membranes to prevent the transfer of desiccant droplets to the airstream, which guarantee high levels of indoor air quality. When a LAMEE is used for air cooling and dehumidifying, energy of phase change is released as the desiccant solution absorbs moisture from the humid airstream. Consequently, the temperature of the desiccant solution increases as it flows along the exchanger which decreases the LAMEE’s effectiveness. A 3-fluid LAMEE is a novel type of LAMEEs which includes a cooling water circuit to cool the desiccant solution along the exchanger. The main contribution of this paper is that it quantifies for the first time the amount of phase change energy released in liquid desiccant energy exchangers used for air cooling and dehumidifying process.

This paper investigates the possibility of using a Tesla turbine as an alternative air-conditioning compressor drive unit rather than the traditional method of linking the compressor rotor to the vehicle engine crank-shaft belt or chain. Interest in Tesla turbines has recently gained momentum due to the possibility in obtaining high efficiency in energy conversion, as claimed by the inventor Nikola Tesla. This paper investigates the possibility of driving the air-conditioning compressor using the hydraulic energy available in the engine lubrication oil piping provided by the engine oil pump. Tesla turbines are easy to adapt and can cover a range of flow rate capacities. Using such a system for energy conversion can lower capital equipment costs and improve the turbine life span. Contributing to sustainable engineering development.

This paper provides an overview of recent refinements to the Radiant Time Series Method (RTSM) as part of 1616-RP. These refinements include replacing the ASHRAE three-parameter (A,B,C) clear sky model with a new globally-applicable model, introducing new design day temperature profiles, updating the weather data, and improving the treatment of interior shading in the fenestration model. In addition, the sensitivity of the calculated cooling loads to the weather-related refinements is investigated with a parametric study.

This paper extends the application of a correlation developed previously by the author for the overall heat transfer coefficients (the U-factors) of single layered fiberglass Metal Building (MB) insulation assemblies to assemblies where insulation is used in a manner designed to fill up the space (the “cavity”) between the two consecutive structural elements (purlins or girts). These assemblies may involve either single or multiple insulation layers and the cavity may be filled to various extents. The paper describes a general technical approach to calculate the thermal resistances of various regions of a MB insulation assembly, namely regions beyond, underneath, and above the structural units.

The occupancy patterns in office buildings have been becoming increasingly diverse. And, even in cases where the occupancy periods are still rigid, the time needed to bring a room from nighttime setback temperatures to the setpoint temperatures not only change in time but also vary between offices. Consequently, operators have been challenged to choose conservatively short temperature setback periods. In recognition of these challenges, a self-adaptive control algorithm that can learn the recurring occupancy patterns and the parameters of a model predicting the indoor temperature response was implemented in a southwest-facing shared office space in Ottawa, Canada.

Stationary gas turbines used in industrial applications can be run using pre-mixed air/fuel systems. Though pre-mixed air/fuel systems are widely established, research continues to further develop the efficiency of such engines. This paper uses computer numerical simulation in analyzing the effects of the pre-mixed air/fuel composition on the performance of a miniature gas turbine. The composition of the fuel-air pre-mixture was varied, results were recorded and compared. Effects on turbulence intensity in the combustion zone for various pre-mixed air/fuel compositions were monitored and compared. The analysis has shown that performance can be optimized with an optimal air/fuel pre-mixture, and that this optimal performance coincides with peak turbulence intensity at the combustion chamber downstream of the pre-mixed air/fuel injectors.

While the possible impact of refrigerant leaks and subsequent dispersion in an occupied space pertains to a wide variety of applications, dynamic models that accurately describe dispersion phenomena in the built environment have not been extensively explored in the literature. This paper builds on previous work by assessing the performance of well-mixed models via a comparison to computational fluid dynamics simulations and studying the behavior of refrigerant dispersion in multiple connected spaces. Results indicate that the well-mixed models are not able to capture variation in the geometric parameters very accurately, and should be used cautiously, while the studies of the dynamics in multiple spaces highlights the importance of the location of ventilation sources and sinks.

This paper investigates the performance of liquid overfeed and DX refrigeration systems and includes components performance and system balance. This project includes the design of two refrigeration circuits, liquid overfeed flooded and DX with a common condenser, and analyzes the performance of the heat exchangers and their impact on the overall circuit’s performance. Several design techniques and methods are considered, including geometry and construction of heat exchangers. The performance of the two circuits is compared for four operating temperatures: -20°C (-4°F), -10°C (14°F), 0°C (32°F) and 5°C (4°F) and analyzed to ascertain circuits operation. DX evaporators are often utilized operating at -10°C (14°F) and below for relatively small duty systems, below 25kW (7.1 TR). However, liquid overfeed flooded evaporators’ are rarely seen practically for systems in this range. The performance of the DX and liquid overfeed flooded evaporators’ is also analyzed for small duties at the four operating conditions.

The eighty-year-old single pressure absorption refrigeration system invented by Albert Einstein and Leo Szilard is attractive as it has no mechanical moving parts and can be driven by heat alone. The literature on the refrigeration system is scarce and only theoretical analyses are available. In this paper, adversities of the primitive design and the operation of the refrigerator prototype are discussed. The prototype is able to achieve temperatures between 8°C and 14°C. Five pairs of heat inputs between 53 W and 111 W are studied. Cooling capacities decrease (from 34 W to 15 W) when the generator heat input increases, but cooling capacities increase (from 17 W to 30 W) when the bubble pump heat input increases. The highest COP is 0.25 when the heat inputs to generator is 53 W and to bubble pump is 89 W. The ideal cooling capacity and COP are 40 W and 0.28, respectively.

This paper is the first part of two papers that report on the results of the ASHRAE-RP 1468 project. This paper presents an overview of the project and the three volumes of documentation included in the final report. The purpose of the project was to produce reference models and guidelines for developing software to automate thermal model creation from a Building Information Model (BIM) into a Building Energy Simulation (BES) for energy simulations. This paper describes the methods of the research and presents highlights of the guidelines.

This paper presents an experimental and numerical study focusing on the development of control-oriented thermal models of varying resolution for an actively charged/discharged phase change material thermal energy storage (PCM TES) system intended for building integration. This PCM TES system consists of five layers of PCM panels with an air channel between the middle layers. Conditioned air is drawn through the cavity to charge and discharge the PCM. The PCM TES system is tested in an environmental chamber where its dynamic response was carefully monitored. The monitored data is used for model development and validation. Compared to a detailed 30th order RC model, simplified 4th order and 2nd order models are shown to be able to satisfactorily predict the thermal energy storage and release of the PCM TES system. To simplify the PCM characterization input and to reduce the simulation time, a five-parameter equation is developed to model the PCM specific heat and a four-parameter equation for its thermal conductivity. The presented modeling methodology is applicable for similar PCM TES systems with multiple PCM layers and air flow channels.

This paper presents an experimental and theoretical study of the dynamic response of low mass residential buildings and their respective space heating peak demands for different room temperature set point profiles, with a focus on the impact of thermal model resolution on the peak demand calculation. Experiments were conducted at two identically constructed and highly instrumented houses. The wood floor of one of them is covered with carpet. Their dynamic response to different ramping set point profiles is monitored and analyzed. Equivalent and physically meaningful RC network thermal models for the purpose of model based control are developed for a north zone of the houses.

Buildings account for 40% of CO2 emissions in the UK and around 25% in China. In an attempt to mitigate global warming and reduce greenhouse gas emissions, the UK Government is committed to reduce its greenhouse gas emissions by 80% below the 1990’s level by 2050; China pledged a 40–45% decrease in CO2 emissions per GDP by 2020 against 2005 levels. To achieve these targets, building retrofitting is one of the efficient ways to improve building energy efficiency and the associated CO2 emissions. In order to evaluate the potential energy savings that can be achieved through building retrofit plans, this study aims to assess two levels of deep retrofit in a typical office building. These retrofit scenarios are assessed using numerical simulation of a prototypical building in five climate zones in china as well as London and Aberdeen in the UK. Numerical simulations have been conducted using the EnergyPlus software. The outcomes of this study reveal that deep retrofit in office buildings can potentially achieve up to 54% energy saving compared with the energy consumption of buildings designed in 1980(s). However, economic factors should be also considered in the process of decision making to choose the most appropriate building retrofit strategy.

High performance buildings are becoming more prevalent in new Army construction projects. Unfortunately, these new designs often do not take into account preventive procedures to avoid thermal bridging effects which are localized heat flow between the building interior and exterior. These effects become much more significant as buildings are designed to be highly insulated and better sealed against air leakage. Researchers from the U.S. Army Engineer Research and Development Center - Construction Engineering Research Laboratory (ERDC-CERL) visited several Army installations and used infra-red imaging to survey buildings to identify places in the building envelope where thermal bridging commonly occur. Characteristic construction sections were selected for heat transfer modeling to quantify the thermal bridging impact and develop general mitigation solutions. This manuscript presents examples of the developed U.S. Army ERDC-CERL Thermal Bridge Mitigation Catalog, which includes architectural details thermal bridge modeling values (ψ and U-factors), and schematics of good construction practices to improve the building envelope performance of typical Army facilities. In addition, this work includes developed visual step-by-step sequencing examples to be used by the construction practitioner for the assembly of a properly mitigated thermal bridge detail in the building envelope.

The aim of the “School of the Future” project which receives funding within the EU’s 7th Framework Program, is to design, demonstrate, evaluate and communicate shining examples of how to reach the future high performance building level. School buildings, their owners and their primary users, namely pupils (the next generation) are the focus of the project. Both the energy and indoor environment performance of four demonstration buildings in four European countries and climates is being greatly improved due to holistic retrofits to the building envelope, the service systems, the integration of renewables, and building management systems. This paper describes the EU project, including all results, a comparison of the four demonstration buildings, and a detailed description of the German demonstration project.

Many innovative energy-saving strategies have been implemented in energy efficient and sustainable building design to reduce overall energy use and operational cost. However, measurement of the actual energy usage and verification of implemented energy-saving design and strategies are also required to ensure the building performs as expected. This paper presents a comprehensive evaluation of the energy performance at the Iowa Utilities Board and Office of Consumer Advocate (IUB-OCA) building by examining annual detailed sub-metered data.

Air leakage data from six parallel fan powered terminal units that utilized electronically commutated motors were evaluated to determine if simple models of air leakage could be developed for applications in building energy simulation programs. The data is from an earlier investigation by Edmondson et al (2011). Units with both 8 in. (20.3 cm) and 12 in. (30.5 cm) primary inlets from three manufacturers were evaluated. The analysis included the impact of downstream static pressure, upstream static pressure, and primary airflow on the leakage from the units.

Outdoor airflow rate, building static pressure, supply air duct static pressure and relief air plenum static pressure, as controlled variables, are maintained by modulating the speed of the supply and return fans and the position of the outdoor, recirculating, and relief air dampers in an air handling unit (AHU). In practice, the three dampers are interlinked completely or partially to match independent control inputs with the controlled variables. The traditional damper control has all the three dampers interlinked with no control over the relief air plenum static pressure. The reverse relief airflow might occur as the outdoor air damper approaches the closed position. To prevent the reverse airflow, one of solutions is to decouple the relief air damper and maintain positive static pressure at the relief air plenum. Two control methods are available based on the control loop design.

ASHRAE Grant-in-Aid Graduate Student Research Paper: This study presents a summary of experimental measurements on the airflow characteristics and pollution distribution around a non-breathing thermal manikin. The two objectives are: To examine the extent to which personal (body posture, clothing insulation, table positioning) and environmental factors (room air temperature and ventilation flow) affect the airflow characteristic (velocity and temperature) around the thermal manikin. To examine the pollution distribution within the convective boundary layer (CBL) around a thermal manikin and personal exposure to two types of airborne pollutants under factors that influence the CBL.

This is the first in a series of technical papers written to describe results of ASHRAE research project 1544. Hot water use in hotels and its associated energy use is significant. However, information on hotel hot water use patterns has been limited until now, resulting in most hotel hot water systems being designed using extremely old hot water use data (45-80 years old) that predate the introduction of water and energy efficient fixtures and appliances. In recognition of this fact, ASHRAE funded research project 1544 “Establishing Benchmark Levels and Patterns of Commercial Hot Water Use – Hotels” to both develop a monitoring methodology that could be duplicated by others to collect hot water use data from a larger number of hotels, and to obtain updated hot water use information from at least two hotels. This first paper describes the technique used to locate and solicit participating hotels, details about the hotels tested, and the instrumentation, data collection approach and equipment used in the field test effort.

This is the second in a series of technical papers written to describe results of ASHRAE research project 1544. Hot water use in hotels and its associated energy use is significant. However, information on hotel hot water use patterns has been limited until now, resulting in most hotel hot water systems being designed using extremely old hot water use data (45-80 years old) that predate the introduction of water and energy efficient fixtures and appliances. In recognition of this fact, ASHRAE funded research project 1544 “Establishing Benchmark Levels and Patterns of Commercial Hot Water Use – Hotels” to both develop a monitoring methodology that could be duplicated by others to collect hot water use data from a larger number of hotels, and to obtain updated hot water use information from at least two hotels. This second paper describes data collected from a “travel” style hotel having no meeting rooms or commercial food service.

This is the third in a series of technical papers written to describe results of ASHRAE research project 1544. Hot water use in hotels and its associated energy use is significant. However, information on hotel hot water use patterns has been limited until now, resulting in most hotel hot water systems being designed using extremely old hot water use data (45-80 years old) that predate the introduction of water and energy efficient fixtures and appliances. In recognition of this fact, ASHRAE funded research project 1544 “Establishing Benchmark Levels and Patterns of Commercial Hot Water Use – Hotels” to both develop a monitoring methodology that could be duplicated by others to collect hot water use data from a larger number of hotels, and to obtain updated hot water use information from at least two hotels. This third paper describes data collected from a “business” style hotel having multiple meeting rooms and several restaurants and thus a commercial kitchen.

Automated detection of schedule- and operation-related energy savings opportunities in commercial buildings can help building owners lower operating expenses while also reducing the adverse societal impacts such as global greenhouse gas emissions. We propose automated methods of identifying certain energy efficiency opportunities in commercial buildings using only whole-building electricity consumption and local climate data. Our two-step approach uses piecewise linear regression and density-based clustering to detect both schedule- and operation-related electricity consumption faults. This paper discusses results obtained from applying this approach to two office buildings and two residential buildings meant to demonstrate our model’s effectiveness in identifying such energy efficiency opportunities. Ways by which the analysis results can be conveniently and succinctly presented to building managers and operators are also suggested.

On the establishment of a reliable baselines for energy savings estimation, one or more variables are usually used to determine a model by regression analysis. These regression models generally use one or more independent variables, such as outside air temperature (OAT), degree days, or combination of these with occupancy or humidity. Based in a calibrated multi-use building energy simulation in a hot and humid climates, in this paper the study of the influence of outside air intake fraction on the selection of the best parameter to develop change-point regression modeling for cooling and heating energy use was evaluated. A comparison among regressions based on three variables, two regularly used in measuring and verification (M&V) process – OAT and outside air enthalpy (OAE), plus the addition of an operational enthalpy was carried out. The study included variations of the outside air intake fraction in the range of 10% -100% and the development of the corresponding patterns of regression models for each of the parameters.

Energy modelling and optimization studies can facilitate the design of cost-effective, low-energy buildings. However, this process inevitably involves early assumptions of unknowns such as predicting occupant behavior, future climate and econometric assumptions. As presently practiced, energy modelers typically do not quantify the implications of these unknown into performance outcomes. This paper describes an energy modelling approach to quantify economic risk and better inform decision-makers of the economic feasibility of a project. The proposed methodology suggests how economic uncertainty can be quantified within an optimization framework. This approach improves modelling outcomes by factoring in the effect of variability in assumptions and improves confidence in simulation results. The methodology is demonstrated using a net-zero energy commercial office building case-study located in London, ON.

There is a trend towards high-rise residential buildings with large glazed areas – often floor-to-ceiling. In most climates, these buildings are reliant on mechanical systems to maintain comfort as a result of the poor insulating properties and high solar transmittance of the glazing. In the summer they are prone to overheating from high solar gains; in the winter, they are prone to thermal discomfort due to low surface temperatures and high heat loss through poorly-insulated glazing and other façade components. Thus, such buildings are vulnerable to power failures, mechanical system failures, and extended demand response strategies. Furthermore, such buildings can be uncomfortable and high in energy consumption during normal operation. This paper describes a methodology to evaluate building resilience using simulation methods. Several resilience metrics were developed or obtained from the literature including: thermal autonomy and passive survivability. A Toronto, Canada-based case study was performed to assess the effect of various passive design strategies to improve resilience. Results showed that thermal autonomy was very poor without occupant interaction. However, this did not translate to poor passive survivability; relatively comfortable conditions were maintained for at least two to three days after power failures.

We introduce and provide results from a rigorous, scientific testing methodology that allows pure building model calibration systems to be compared fairly to traditional output error (e.g. how well does simulation output match utility bills?) as well as input-side error (e.g. how well, variable-by-variable, did the calibration capture the true building's description?). This system is then used to generate data for a correlation study of output and input error measures that validates CV(RMSE) and NMBE metrics put forth by ASHRAE Guideline 14 and suggests possible alternatives.