Absorption systems are an alternative to vapor compression systems due to the high requirements of electrical energy involved in the vapor compression systems. Researchers are concentrating to improve the performance of absorptions systems, and one of the possible ways is to analyze different losses associated in each component of an absorption system using an exergy approach. In this paper, energy and exergy analysis of the single-effect lithium bromide/water absorption chiller system has been carried out. A computer-based simulation model has been developed for parametric investigation of the system which also analyses the effect of generator temperature on the exergy losses in different components of the system. The irreversibility rate in thegeneratorhasbeenfoundtobethe highest when compared with the other components involved in the system. The coefficient of performance (COP) is found to be in the range of 0.85–0.93 for a given set of operations parameters.

Citation: ASHRAE Transactions - Volume 120, Part 2, Seattle, WA

Fan-powered terminal units (FPTUs) are composed of three main components: the fan/motor/controller, damper, and housing. These three components were experimentally characterized separately to determine if the overall system performance of series FPTU could be predicted by combining the models of the three components. Eight terminal units, from three manufacturers, with 8 in. (203 mm) and 12 in. (304 mm) primary air inlets were studied.

Fan airflow and power data were collected fromeight fans with electronically commutated motors (ECMs) over a range of fan speeds and discharge static pressures. Semi-empirical models were developed from the experimental data. Model variables included the nondimensional fan speed and the discharge static pressure. The resulting models had a coefficient of determination (R2) value greater than 0.99 for fan airflow model and 0.97 for power consumption model. These models can be applied to HVAC simulation programs to model variable-air-volume (VAV) systems with series FPTU.

Citation: ASHRAE Transactions - Volume 120, Part 2, Seattle, WA

This product is a PDF that contains links to files that consist of PowerPoint slides synchronized with the audio-recording of the speaker (recorded presentation), PDF files of the slides, and audio only (mp3) as noted.

The first step on geothermal heat pump projects is assessing project sites for ground heat exchanger viability. This includes understanding the local regulatory requirements, permitting and hydrogeology. It also requires design engineers to estimate through calculation or testing the local formation properties and the size and type of ground heat exchanger. The speakers in this session discuss the science and engineering for selecting and developing site data application for designing ground heat exchangers on commercial projects.

1. Site Characterization for Geothermal Heat Pump Systems
   John Rhyner, PW Grosser Consulting, Bohemia, NY
   Product Contains: Slides (pdf), Recorded Presentation, Audio (mp3)
2. Ground Heat Exchanger Design Considerations for Proper Integration with the Building System
   Warren (Trey) Austin III, P.E., Member, Geo-Energy Services, Littleton, CO
   Product Contains: Slides (pdf), Recorded Presentation, Audio (mp3)

Citation: ASHRAE Seminar Recordings, 2014 Annual Conference, Seattle, WA

This paper presents a set of asset business value models (BVMs) that map individual buildings and groups of buildings from their business objectives to the constituent assets whose operations are critical for the accomplishment of those business objectives. The outputs of these BVMs then provide inputs to asset management processes for the allocation of investment in labor and materials and for the organization of maintenance workflow. The two types of value models presented in this paper provide ordinal (criticality) or monetary business value scores for assets. The first BVM maps the business objectives designated by an organization for a building to that building’s selected critical assets, using qualitative and subjective indices to yield an ordinal criticality score for those assets; the second BVM quantifies the business value of those assets in economic terms, using a monetary metric.

Citation: ASHRAE Transactions - Volume 120, Part 2, Seattle, WA

This product is a PDF that contains links to files that consist of PowerPoint slides synchronized with the audio-recording of the speaker (recorded presentation), PDF files of the slides, and audio only (mp3) as noted.

This session has two overall objectives and a separate speaker addressing each. The first speaker addresses the history of ground source heat pumps (GSHP), providing an overview of the many ways the technology has been applied as well as attempts to apply, including those that failed or were eclipsed by others. The second speaker provides an overview of the contents of the many sessions within the Ground Source Heat Pumps State of the Art: Design, Performance and Research track.

1. History of Geothermal Heating and Cooling Systems
   Steve Smith, Enertech Global, LLC, Greenville, IL
   Product Contains: Slides (pdf), Recorded Presentation, Audio (mp3)
2. Overview of the Geothermal Track at This Meeting
   Gary Phetteplace, Ph.D., P.E., Member, GWA Research LLC, Lyme, NH
   Product Contains: Slides (pdf), Recorded Presentation, Audio (mp3)

Citation: ASHRAE Seminar Recordings, 2014 Annual Conference, Seattle, WA

Exergetic analysis of a typical hot-water condensing boiler (HWCB) was carried out using the general equation for hot-water/steam boilers. Good correlation with results reported in the literature was found. Significant discrepancy between condensing boiler exergetic efficiency and energetic efficiency is demonstrated. The same method is applied to estimate theoretical exergetic efficiency of a proposed vapor vacuum heating and condensing boiler (VVHCB) combo. Comparative calculation for a Boston area house heated by a condensing boiler indicated potential savings of 43.8% energy/fuel for the VVHCB alternative.

Citation: ASHRAE Transactions - Volume 120, Part 2, Seattle, WA

Generalized one- and two-time-constant models used to capture the evolution of the capacity of geothermal heat pumps at compressor start-up are presented. A one-time-constant model for the capacity decay at compressor shutdown is also presented. The determination of these time constants is important as longer time constants lead to more degradation of the heat pump performance in cycling conditions. Various reference time constants are obtained from a detailed and experimentally validated dynamic model of a geothermal heat pump in a range of operating conditions in heating or cooling mode. These dynamic empirical models are efficient and are more appropriate to whole-building energy simulation than corresponding deterministic models. It is shown that, contrary to the impression that may come from the literature, time constants change according to operating conditions. In particular, if the runtime decreases, the time constants tend to increase in the heating mode and to decrease in the cooling mode. They increase with the inlet water temperature (IWT) and decrease if the pressures are allowed to equalize at compressor shutdown. Finally, the time constants tend to increase when the fan is continuously operating. A time-constant-based heat pump model is derived and implemented in the dynamic energy simulation software TRNSYS.

Citation: ASHRAE Transactions - Volume 120, Part 2, Seattle, WA

The goal of this study was to investigate how well the performance of a series fan-powered terminal unit (FPTU) could be predicted by combining the models of its individual components, namely fan/motor/controller, damper, and housing. Eight series FTPUs, from three manufacturers, with electronically commutated motors (ECMs) were investigated. In Part I of this paper, the fan airflow and power performance were experimentally studied. The corresponding empirical models were established fromthe measured data.Part II of this paper described the development of primary and plenum airflow models by testing dampers and housings. The primary airflow model predicted the airflow throughdampers asa function of damper angles and damper differential pressures. The plenum airflow model estimated the amount of air induced into housings by using the housing differential pressures and plenum air inlet areas. The overall performance of a series FPTU was evaluated by systematically assembling its component models.

Comparisons were made between model outputs and experimental data from previous studies. While the predicted airflows were in agreement with measurements, the componentbased model underestimated fan-power consumptions for some units. This discrepancy may be caused by fan-system effects that occur as a consequence of flow mixing and swirl inside housings. These flow distortions create a condition that is different from the condition used in the laboratory fan tests.

Citation: ASHRAE Transactions - Volume 120, Part 2, Seattle, WA

The aim of this paper is to show how the number and positioning of boreholes for a given land surface area can affect the fluid and ground temperature variations and the required borehole length. The methodology uses a g-function generation model and then uses temporal superposition to predict the variation of the fluid and borehole wall temperatures over 20 years of operation of the ground-source heat pump system. The cases of a 3 x 7 and 5 x 10 bore field are studied. Results show that the position of boreholes within a bore field of constant land area affects only slightly the required borehole length, while the number of boreholes has a greater, albeit small, impact on the required length. For instance, for the 5 x 10 bore field, the total required borehole length increases by 0.9% when boreholes are displaced towards the center and decreases by 2% when the field was changed to a 5 x 9 configuration. In the latter case, the length of individual boreholes increased by 8.8%.

Citation: ASHRAE Transactions - Volume 120, Part 2, Seattle, WA

This product is a PDF that contains links to files that consist of PowerPoint slides synchronized with the audio-recording of the speaker (recorded presentation), PDF files of the slides, and audio only (mp3) as noted.

University science buildings are typically the highest net energy users on a campus. This project combined a centralized geothermal heating/cooling plant, a dedicated outside air system, active chilled beams, thermally-massive radiant heating/cooling and self-learning adaptive controls. The system is designed to use geothermal loop water directly for sensible cooling without needing a chiller. A magnetic-bearing chiller provides chilled water for the dedicated outdoor air system (DOAS) unit and hot water for heating. Net onsite energy consumption for the first year of operation was 64 KBTU per square foot.

1. Geothermal HVAC Case Study: Davis Building, University of Findlay
   Stephen A. Hamstra, P.E., Member, Greensleeves LLC, Zeeland, MI
   Product Contains: Slides (pdf), Recorded Presentation, Audio (mp3)
2. Geothermal HVAC Case Study: Success in K-12 Schools and Nation's Largest Net Zero School
   Don Penn, P.E., Member, Image Engineering Group, Ltd., Grapevine, TX
   Product Contains: Slides (pdf), Recorded Presentation, Audio (mp3)
3. Geothermal HVAC Case Study: Fast Food Restaurant, Pensacola, FL
   Greg Tinkler, P.E., Member, Redding Linden Burr Consulting Engineers, Houston, TX
   Product Contains: Slides (pdf), Recorded Presentation, Audio (mp3)

Citation: ASHRAE Seminar Recordings, 2014 Annual Conference, Seattle, WA

Originally a mid-sized Midwestern U.S. power plant controlled airflow rate used for combustion by dampers. This airflow rate that travels through the boiler and scrubber pollution control device is provided by centrifugal blowers powered by two 4000 hp (3.0 MW) and two 3000 hp (2.2 MW) motors. Variable-frequency drives (VFDs) were installed to power these motors and analysis was made by examining the electrical current of the motors approximately one year before and after VFD installation. After installation, the VFD was operated manually and airflow was still partially controlled by the dampers, hence not saving the maximum amount of electricity. Even operating this way, however, the analysis showed that the VFDs saved 22.76 GWh annually. This power plant assumes a cost of $0.04/kWh for electricity produced, therefore, the project saves $910,440 annually and the total project cost was $2.9 million. In addition, grants providing $2 million of these funds greatly improving the profitability. The project was a success, providingVFDs with a long life expectancy that saves a significant amount of electricity for an appropriate initial cost.

Citation: ASHRAE Transactions - Volume 120, Part 2, Seattle, WA

This article presents a novel framework by integrating the existing asset management theory with building simulation technology to develop effective and optimal maintenance strategies for the purpose of reducing the energy footprint of buildings while ensuring that building performance and business objectives are met. The optimality criteria take into account not only the energy consumption in engineering terms, but also the value that the building assets generate with respect to building business missions and objectives.

An energy efficient asset with minimal stoppages due to failures or replacements, coupled with minimal loss of productivity due to occupant discomfort would certainly generate high asset values. A computationally efficient optimization algorithm is also presented to overcome computational deficiencies of building energy simulation models in lieu of long simulation runs. Through several case studies, we argue that while the maintenance plans seem intuitive, especially by experts, the details of these plans (together with cost factors that are broken down into energy, maintenance, and penalty terms) can significantly help facility managers and building owners to strategize their investments and maximize their annual return on savings. The optimization engine is sufficiently flexible to connect to different simulation engine and forecasting models, and is also able to receive near real time and historical data from different platforms.

Citation: ASHRAE Transactions - Volume 120, Part 2, Seattle, WA

For 40 years, dating back to the adoption of insulation requirements for residential buildings in 1974, the City of Seattle has had strong policies to support energy efficiency in buildings. While Seattle has followed the progress of national standards, Seattle has sought greater energy efficiency. From a Seattle public advisory group recommendation in the late 1970s for a 20% energy savings in the building envelope compared to ASHRAE Standard 90-75 to a Seattle City Council resolution in 2001 requiring that city staff bring forward amendments for each update to the Seattle Energy Code to achieve a 20% total building energy savings compared to the latest version of ASHRAE/IES Standard 90.1, the incorporation of advances in the energy efficiency of fenestration products has been a key component.

To achieve the energy savings expected, there has been dedicated effort on implementation and seeing what lessons can be learned.When the 1986Washington State Energy Code specified thermal testing of fenestration products and no entity was compiling such information, Seattle required manufacturers to submit their test reports and published a list of tested product performance. By 1991, Client Assistance Memo 403 had grown to include close to 1000 products. Seattle analysis of the test results then revealed anomalies. Lack of sufficient oversight of the testing laboratories and credibility concerns subsequently led to the founding of the National Fenestration Rating Council (NFRC).

In the 20 years since NFRC published Technical Procedure 100 for rating fenestration product U-factors in 1991, the NFRC rating procedures have been embraced by federal law and adopted into national energy standards and codes, providing a reputable basis for assessment. NFRC’s initial focus was fenestration products that leave a manufacturing plant fully assembled. Now most of those fenestration products are shipped with an NFRC label listing the overall product U-factor, solar heat gain coefficient (SHGC), and visible transmittance (VT).

For site-assembled fenestration products (such as curtain walls, window walls, and storefronts),NFRChas offered alternative labeling options, including the NFRC Site Built Label Certificate program adopted in 1999 and the NFRC Component Modeling Approach (CMA) Label Certificate program adopted in 2009.

This paper contains a summary of the Seattle Energy Code requirements for fenestration products with a focus on siteassembled fenestration products. The paper provides highlights of energy-efficiency advances that fenestration product manufacturers brought to the Seattle area in response to the Seattle Energy Code requirements during the NFRC Site Built Label Certificate era. The paper then provides a detailed assessment of the fenestration products in all 169 of the NFRC CMA Label Certificates issued between 2010 and 2013 with Seattle addresses in response to more recent Seattle Energy Codes.

Improvements in the energy efficiency of fenestration products will continue to be essential as policy makers and designers, and building operators and occupants, seek further savings in building energy consumption. This summary provides a snapshot of where the fenestration industry is now in Seattle and notes advanced fenestration products that have already been installed, illustrating options for consideration for more widespread energy savings.

Citation: ASHRAE Transactions - Volume 120, Part 2, Seattle, WA