Monday, January 30, 2017

This article proves that the use of Fan Law Equations to calculate changes in air flow and pressure lead to significant errors in cases where air handling units have considerable internal resistance. It also demonstrates methodologies for a more accurate calculation of fan system parameters.

The work was completed under ASHRAE Research Project 1467-RP Balancing Latent Heat Load between Display Cases and Store Comfort Cooling. The overall objective is to provide a comprehensive assessment of the potential for energy savings in supermarkets by optimized design and operation of the combined HVAC and refrigeration systems. The research addresses the impact of supermarket design, HVAC and refrigeration system design, temperature and humidity setpoints, and store location. The study uses EnergyPlus as the simulation tool for modeling supermarkets, and generally found good agreement with both measured results and expected outcomes on an individual variable level.

The primary objective of the 1609 research project was to formally specify information exchange use cases for O&M work processes based on existing ASHRAE publications. Four use cases were developed from Guideline 4, Standard 180, Service Life and Maintenance Cost database, and Standard 105. A fifth combined use case, focused on asset management. A User Guide was written to help practitioners implement a practical asset management program. These products can be adopted by O&M professionals to bring Building Information Modeling (BIM) techniques into their practice and increase ASHRAE involvement in adopting BIM technologies to support its members’ work processes.

One of the critical tasks of the International Energy Agency’s Energy Conservation in Buildings and Communities (IEC ECBC) Program’s Annex 61 “Business and Technical Concepts for Deep Energy Retrofit (DER) of Public Buildings” is to develop bundles of core technologies (measures), which, when applied in major renovation projects to older (pre-1980) buildings, allow site energy reduction by 50% or better compared to the pre-renovation baseline. This paper shows that application of a core technologies bundle to dining facilities, which have high process loads and ventilation requirements, significantly improves energy use in the building compared to the typical renovation scenario.

Presidio of Monterey, host to the military’s premier language training institute, faces the same challenges as other Army bases in managing its aging building stock. This paper demonstrates the acquisitions strategies employed and field lessons learned in an attempt to better guide prospective DER project stakeholders. This project employed a regimented process to its various contracting phases with some strategic augmentation to support the DER method that are transferrable to similar retrofit efforts. There have also been many process-based and technical takeaways that can be used to bolster future DER work at Presidio, in the Army, and throughout the sustainability industry.

Deep energy retrofits can supercharge our transition to a clean energy future without relying on radical technologies or untested methods. Buildings are the largest energy-consuming sector in the United States and 80% of existing buildings today will likely remain in operation by 2030, making existing building retrofits essential to national and global energy and carbon reduction strategies. There are three main funding mechanisms to deliver deep energy retrofits to federal facilities: congressionally appropriated funding, performance contracting, including commonly used energy savings performance contracts (ESPCs) and a combined funding model blending appropriations with ESPC. This paper focuses on ESPCs and the emerging combined funding model.

In this study, heat transfer coefficients for radiant floor heating systems were investigated in a special test chamber that is one of the very first implementation of the ANSI/ASHRAE Standard 138 in the world. Radiant systems offer high energy and exergy efficient sensible heating and cooling potential. These systems can be directly coupled with low enthalpy, renewable or waste heat resources. Heat transfer coefficients are important design parameters for radiant systems that effects the heat transfer capacity of the heated/cooled surface to indoor. In this study, radiant, convective and total heat transfer coefficients for radiant floor heating are investigated experimentally.

As Semi-Transparent Photovoltaic (STPV) windows are advancing within the building and window industry, the need for deeper understanding and quantification of key performance parameters such as the solar heat gain coefficient (SHGC), operating temperature profile and electrical power output is required. This study proposes an experimental methodology suited to the determination of the SHGC of STPV windows. The methodology presented utilizes an indoor solar simulator and calorimeter facility. A SHGC reduction from 2% to 20% was estimated, when the STPV windows were tested with no-load and with load applied at maximum power point.

The study describes an experimental and simulation study to estimate load handling capacity and thermal performance of radiant cooling system installed in existing building in India. To evaluate thermal performance and capacity, experiments are conducted and simulations were carried out using EnergyPlus tool. Building model was calibrated using the experimental results and a parametric analysis at different operating condition has been done on calibrated model. The results are validated by evaluating the characteristic performance exponent (nco’’) given in ASHRAE Standard 138.

A solar collector cum regenerator (C/R) is a key component of a liquid desiccant air cooling system that concentrates liquid desiccant flowing over its absorber surface. Simultaneous collection of solar energy and evaporation of water occurs as the solution flows over the absorber surface of the solar C/R being exposed to the ambient air throughout sunshine period. This paper discusses the use of a single solution tank for regeneration of liquid desiccants (LiCl and CaCl2 solutions) using a solar C/R of absorber area 4.0 m2 using experimentally collected data sets in a day (9am up to 4 pm) across seasons.

The present study focused on the effect of supply air temperature on air distribution in a room with floor heating (FH) or ceiling heating (CH) and mixing ventilation (MV) or displacement ventilation (DV). The vertical distribution of air temperature and velocity in the occupied zone and the horizontal distribution of containment concentration in the breathing zone were measured as the supply air temperature ranged from 15.0℃ to 19.0℃. The results showed that the vertical air temperature differences were less than 0.3℃ with FH+MV or CH+MV and between 1.9℃ and 4.2℃ with FH+DV or CH+DV. The turbulence intensity varied from 12.5% to 15.5% with FH+MV or CH+MV, and from 6.0% to 10.8% with FH+DV or CH+DV. The air distribution effectiveness was close to 1.0 with FH+MV or CH+MV, and between 1.06 and 1.16 with FH+DV or CH+DV. The results in this paper are relevant to the design and control of the hybrid systems with radiant heating systems and mechanical ventilation systems.

Many organizations take pride in improving the energy efficiency of their buildings through certifications such as Leadership in Energy and Environmental Design (LEED). However, due to limited accountability for energy consumption on a building level, particularly after some period of operation, LEED certification may not necessarily translate into efficient building operation in the long run. This paper details an energy analysis and a building energy simulation of a LEED Silver dining hall which was diagnosed with poor energy efficiency performance and appeared among Facilities Management list of buildings that needed prompt attention on the University of Maryland’s (UMD) campus.

Laboratory facilities remain expensive to operate because of the extraordinary volume of once-through exhaust air required by chemical fume hoods. Traditionally, laboratory fume hood operation is perceived as a laminar flow process to capture and contain contaminants inside the hood, and relies on face velocity to establish the volume of air required when the hood is in use. Conversely, vortex fume hood operation is understood as a dilution process that utilizes turbulence to dissolve and contain contaminants in the air stream and employs air changes per minute to establish the volume of air that passes through the hood.

The phase-out of hydrochlorofluorocarbon (HCFC) refrigerants in developing countries is currently under way according to the Montreal Protocol. R-22 is one of the most commonly used HCFCs in the developing nations. It is extremely well suited for air conditioning and refrigeration (AC&R) in high ambient temperature environments. Non-Article 5 countries have already gone through the phase-out of HCFCs and settled on using R-410A as the refrigerant of choice for AC applications. Previous studies have shown that R-410A results in significant capacity and performance degradation at higher ambient temperature conditions. There is a growing concern about finding alternative refrigerants to R-22 that would have zero ozone depletion potential (ODP), lower global warming potential (GWP), and at the same time maintain acceptable performance at higher ambient temperatures. Furthermore, the developed world’s transition through higher GWP refrigerants such as hydrofluorocarbons (HFCs) and HFC blends resulted in significant direct CO2 equivalent emissions. It is imperative to develop a bridge for developing nations to avoid the transition from HCFC to HFC and then from HFC to alternative lower GWP refrigerants. This paper summarizes data from an experimental campaign on alternative refrigerant evaluation for R-22 and R-410A substitutes for mini-split air conditioners designed for high ambient temperature environments. The experimental evaluation was performed according to ANSI/ASHRAE Standard 37, and the performance was rated at test conditions specified by ANSI/AHRI 210-240 and ISO 5151.

Variable speed heat pump systems offer capabilities for advanced control strategies that coordinate the operation of compressor, valve and fans to maximize efficiency while tracking changing heating and cooling loads. However, advanced multivariable controllers can be more complex to design, implement and troubleshoot. This paper presents energy optimal coordinated control strategies, with varying levels of complexity, ranging from decoupled PID control to Linear Quadratic Gaussian (LQG) multivariable control. The advantages and disadvantages of the three strategies are analyzed and compared in simulation and experiment.

Frosting in air-to-air energy exchangers is a common problem when the outdoor air temperature is very low. Membrane-based air-to-air energy exchangers which are capable of moisture transfer as well as sensible heat transfer may assist in overcoming frosting. To understand the effect of water vapor transfer on frosting, laboratory experiments are conducted to investigate the frosting conditions for two geometrically identical air-to-air cross-flow plate exchangers. One exchanger is made with a water vapor permeable membrane (energy exchanger), while the other exchanger is made with an impermeable polymer film with similar thickness (heat exchanger).

This paper discusses strategies to improve the cost efficiency of DER. In most cases a DER is started with a general refurbishment which covers all major non energy related investments and the investments to accomplish the minimum energy requirement for the building stock. The cost efficiency for any measure beyond the minimum energy requirements will be accomplished by accounting the energy savings in pay back periods of less of half of the average life cycle of the building; this might be acceptable for the public sector but will find no large acceptance in the commercial sector.

Fossil fuels including petroleum, coal and natural gas are being currently used as energy sources resulting in global warming. Energy consumed by buildings accounts for about 40% of the total energy consumption. Further, heat losses through windows inside buildings account for 20-40% of cooling and heating loads. In addition, various studies on energy saving are being carried out. In the present study, tightness of windows has been analyzed according to KS F 2292 by using sliding and high-performing lift sliding windows. Further, TRNSYS17 has been used to analyze infiltration and heating load with respect to lock operation and location.

Due to high installation costs and space limitations, airflow measurements with physical meters in air handling units are not adequate or/and accurate for energy efficient operations. Virtual airflow sensors that calculate airflow rate based on measurable operational data using fan curves provide a promising alternative. However, in-situ fan curves, rather than the manufacturer’s fan curves, are needed for accurate airflow calculations. This paper explores a comprehensive procedure for accurate in-situ fan curve calibration in variable air volume (VAV) systems by addressing three technical challenges.

As the energy efficiency industry evolves more complex efficiency projects, such as chilled water system upgrades, are being implemented. This is due to both the completion of simpler efficiency projects on many sites and the large room for efficiency improvements in chilled water systems that are custom designed for each application and site. In most cases owners prefer third-party measurement and verification (M&V) of the efficiency projects. Additionally, electrical utilities see benefits in incentivizing and claiming energy efficiency projects. This paper discusses the different available methodologies and their limitations.

Energy models are commonly used to examine the multitude of pathways to achieve high-performance buildings. As presently practiced, a deterministic approach is used to evaluate incremental design improvements to achieve performance targets. However, significant insight can be gained by examining the implications of modelling assumptions using a probabilistic approach. This paper describes a reproducible methodology which aids modelers in identifying energy and economic uncertainties due to variabilities in solar exposure. This approach improves modelling outcomes by factoring in the effect of variability in assumptions and improves confidence in simulation results.

Due to the rapid development of the engineering technology and the improvement of the living environment, the application scope of the fluid machines are becoming more various. In this study a comparative study on some representative anemometers and flow meters, which are used at the local sites, is conducted. It is intended to suggest a new kind of portable flow meter that supplements the existing restriction. Also in this study, an experiment comparing a mass flow meter is conducted in order to confirm the accuracy of the performance of the multi-nozzle testing apparatus conforming to ANSI/ASHRAE 51-1999.

Air conditioning in buildings that house moisture sensitive products like libraries, museums, and supermarkets etc. needs strict control of humidity. The sensible heat ratio in many such applications tend to be low and energy intensive conventional means of humidity control using electrical/gas fired heaters is not finding favor with designers and ASHRAE. Various alternative ways to avoid reheating include Desiccant Rotor System, Plate to Plate Heat Exchanger, Glycol based run around coil, Heat Pipe based Heat Exchanger (HPHE) etc. This paper presents the development of a U- shaped HPHE starting from fabrication of heat pipes to their assembly in tube fin type heat exchanger.

Increasing residential air-conditioning demand and the growing number of solar photovoltaic (PV) systems installed in the residential sector have increased electrical net energy demand fluctuation. These severe fluctuations lead to a need for flexible generation capacities that can rapidly meet the fluctuating demands. To combat these fluctuations, utility companies have introduced different price plans to financially incentivize customers to reduce their demand during certain hours of the day, making residential electricity demand constant (or “flat”) for the daytime hours. This paper explores the feasibility of coupling precooling with PV to achieve “flat” residential net demand in three Phoenix, Arizona homes.

Motor-driven pumps recirculate chilled water and hot water in heating, ventilation and air conditioning systems. The purpose of this paper is to develop an optimal pump sequencing control with improved water-wire efficiency model. First, the wire-to-water efficiency of VFD-motor-pump systems is improved by applying a motor equivalent circuit method to calculate the motor efficiency at variable frequency, and then the wire-to-water efficiency is simulated and applied to develop the optimal operating regions for a secondary chilled water system with three parallel pumps.

This paper investigates the impacts of a wireless heating management system for electrical baseboard heaters in two bulk-metered apartment buildings located in Ottawa, Ontario, Canada. A tenant survey was conducted one year after the initial installation to study the thermal comfort impact of this system. Overall this system has produced promising energy and cost reductions as much as 33% with little negative impact in tenants’ overall thermal comfort during the heating seasons. However, the authors still caution the installation of similar systems and feasibility studies should be performed to determine the suitability of such systems.