Creating Performance Curves For Variable Refrigerant Flow Heat Pumps In EnergyPlus

This document describes methods to generate performance curve coefficients for variable refrigerant flow heat pumps in DOE\u27s EnergyPlus building energy simulation program. Manufactures performance data for capacity and power are used to create full-load and part-load performance curves for cooling and heating operating modes. When performance variations for full-load capacity or power cannot be modeled using a single performance curve, the data set is divided into lower and upper temperature regions and dual performance curves are used. Table objects may also be created to substitute when performance curves do not provide the required accuracy. These performance curves or tables are then used as input data for the variable refrigerant flow heat pump model. The techniques described in this paper can be used to create performance curves for any EnergyPlus equipment model

Case Study of an Innovative HVAC System with Integral Dehumidifier

In most applications, heating, ventilating, and air conditioning (HVAC) equipment is controlled to maintain an indoor dry-bulb set point temperature. Moisture removal by the HVAC system is considered to be an operational byproduct. During summer months, the operation of the HVAC system is usually sufficient to meet both the sensible and latent cooling loads. However, during other times of the year when sensible loads are reduced, the moisture load can be significantly higher than the available moisture removal capacity of the air conditioning system. This can lead to elevated indoor relative humidity levels and an uncomfortable indoor environment. In many cases, designers, engineers and building occupants combat high indoor relative humidity and associated comfort problems with the use of additional dehumidification equipment for both commercial and residential applications. The use of extra dehumidification equipment can be expensive in terms of first cost and annual operating costs. First costs associated with this type of equipment may include additional electrical circuits, condensate drainage, and additional air distribution systems. The loss of usable floor area, localized noise, and zonal “hotspots” can also be considered a cost penalty. As an alternative to using separate equipment for meeting both the sensible and latent components of a building’s cooling load, off-the- shelf products were used to construct a self-contained air handler. The air handler is controlled using a low-cost thermostat and humidistat. The dehumidification element of the system is completely independent from the air conditioner and works nearly the same as conventional dehumidification equipment. At times, both the dehumidification equipment and the air conditioner operate in unison when the need arises. The use of dehumidification equipment integrated with a conventional AC system provides a unique solution for moisture control applications. This paper describes the development and testing of this integrated equipment. Although this technology is not new, the integration of a dehumidification system with a standard air conditioner is an innovative strategy that can be used to address moisture control in buildings. This new HVAC configuration would provide a low-cost solution for building owners and a more comfortable indoor environment for building occupants

Technical Subtopic 2.1: Modeling Variable Refrigerant Flow Heat Pump and Heat Recovery Equipment in EnergyPlus

The University of Central Florida/Florida Solar Energy Center, in cooperation with the Electric Power Research Institute and several variable-refrigerant-flow heat pump (VRF HP) manufacturers, provided a detailed computer model for a VRF HP system in the United States Department of Energy's (U.S. DOE) EnergyPlus? building energy simulation tool. Detailed laboratory testing and field demonstrations were performed to measure equipment performance and compare this performance to both the manufacturer's data and that predicted by the use of this new model through computer simulation. The project goal was to investigate the complex interactions of VRF HP systems from an HVAC system perspective, and explore the operational characteristics of this HVAC system type within a laboratory and real world building environment. Detailed laboratory testing of this advanced HVAC system provided invaluable performance information which does not currently exist in the form required for proper analysis and modeling. This information will also be useful for developing and/or supporting test standards for VRF HP systems. Field testing VRF HP systems also provided performance and operational information pertaining to installation, system configuration, and operational controls. Information collected from both laboratory and field tests were then used to create and validate the VRF HP system computer model which, in turn, provides architects, engineers, and building owners the confidence necessary to accurately and reliably perform building energy simulations. This new VRF HP model is available in the current public release version of DOE?s EnergyPlus software and can be used to investigate building energy use in both new and existing building stock. The general laboratory testing did not use the AHRI Standard 1230 test procedure and instead used an approach designed to measure the field installed full-load operating performance. This projects test methodology used the air enthalpy method where relevant air-side parameters were controlled while collecting output performance data at discreet points of steady-state operation. The primary metrics include system power consumption and zonal heating and cooling capacity. Using this test method, the measured total cooling capacity was somewhat lower than reported by the manufacturer. The measured power was found to be equal to or greater than the manufacturers indicated power. Heating capacity measurements produced similar results. The air-side performance metric was total cooling and heating energy since the computer model uses those same metrics as input to the model. Although the sensible and latent components of total cooling were measured, they are not described in this report. The test methodology set the thermostat set point temperature very low for cooling and very high for heating to measure full-load performance and was originally thought to provide the maximum available capacity. Manufacturers stated that this test method would not accurately measure performance of VRF systems which is now believed to be a true statement. Near the end of the project, an alternate test method was developed to better represent VRF system performance as if field installed. This method of test is preliminarily called the Load Based Method of Test where the load is fixed and the indoor conditions and unit operation are allowed to fluctuate. This test method was only briefly attempted in a laboratory setting but does show promise for future lab testing. Since variable-speed air-conditioners and heat pumps include an on-board control algorithm to modulate capacity, these systems are difficult to test. Manufacturers do have the ability to override internal components to accommodate certification procedures, however, it is unknown if the resulting operation is replicated in the field, or if so, how often. Other studies have shown that variable-speed air-conditioners and heat pumps do out perform their single-speed counterparts though these field studies leave as many questions as they do provide answers. The measured performance of all VRF systems tested did show remarkable agreement with the shape of the manufacturers performance data (i.e., the slope of the measured data versus outdoor temperature had the same or similar slope as reported by the manufacturer). This outcome supports the use of manufacturers performance data, in a normalized format, as performance inputs to the VRF computer model. The questionable model inputs are the rated capacity and COP which, during this project, were found at times to be quite different than reported by manufacturers. Of course, these differences are inherently caused by the different test procedures used to measure performance. Given the accelerated use of variable-speed equipment, further research is warranted to understand the performance of these systems in real world applications. Additional laboratory testing, review and critique of Standards test methods, and further comparison of field measured performance to computer models will provide information necessary to better understand the operational and economic benefits of these systems

Semi-Annual Program Progress Performance Report For University Transportation Systems pppr#8

The major activity of the past reporting period has been the completing of the final project research reports. During the period, twelve projects (numbers 3, 7, 10, 14, 17, 9, 22, 4, 5, 13, 20 and 18) were completed and the final project reports forwarded to DOT and the required associated organizations. Two additional final reports (numbers 12 and 21) are close to being completed. Final reports for the other 4 remaining projects (numbers 2, 8, 11 and 15) are in various stages of completion. For this reporting period, EVTC researchers concluded 12 project final reports, authored one publication, made 4 presentations and held or participated in 8 STEM events. Collaborative efforts for the period included a meeting with GE Energy Management regarding grid management plans, the City of Orlando to discuss the development of a network of smart EV charging stations and a planning effort with Orlando Utilities Commission to develop a scoping document for renovation of an unused building for research and development of EV car and bus applications, use of fuel cells for alternative energy production, building energy efficiency measures, and general public awareness activities

Case Study Of An Innovative HVAC System With Integral Dehumidifier

In most applications, heating, ventilating, and air conditioning (HVAC) equipment is controlled to maintain an indoor dry-bulb set point temperature. Moisture removal by the HVAC system is considered to be an operational byproduct. During summer months, the operation of the HVAC system is usually sufficient to meet both the sensible and latent cooling loads. However, during other times of the year when sensible loads are reduced, the moisture load can be significantly higher than the available moisture removal capacity of the air conditioning system. This can lead to elevated indoor relative humidity levels and an uncomfortable indoor environment. In many cases, designers, engineers and building occupants combat high indoor relative humidity and associated comfort problems with the use of additional dehumidification equipment for both commercial and residential applications. The use of extra dehumidification equipment can be expensive in terms of first cost and annual operating costs. First costs associated with this type of equipment may include additional electrical circuits, condensate drainage, and additional air distribution systems. The loss of usable floor area, localized noise, and zonal hotspots can also be considered a cost penalty. As an alternative to using separate equipment for meeting both the sensible and latent components of a building\u27s cooling load, off-the shelf products were used to construct a self contained air handler. The air handler is controlled using a low-cost thermostat and humidistat. The dehumidification element of the system is completely independent from the air conditioner and works nearly the same as conventional dehumidification equipment. At times, both the dehumidification equipment and the air conditioner operate in unison when the need arises. The use of dehumidification equipment integrated with a conventional AC system provides a unique solution for moisture control applications. This paper describes the development and testing of this integrated equipment. Although this technology is not new, the integration of a dehumidification system with a standard air conditioner is an innovative strategy that can be used to address moisture control in buildings. This new HVAC configuration would provide a low-cost solution for building owners and a more comfortable indoor environment for building occupants

Cost Analysis Of Workplace Charging For Electric Vehicles

This report examines the life-cycle costs associated with the operation of electric vehicle supply equipment (EVSE) and the impact that plug-in electric vehicle (PEV) charging may have on commercial building electricity cost. This study assumed that a utility electric meter was attached to each charging station and that 10 kWh of energy was required to replenish the energy consumed during a typical 35-mile daily work commute. Through a life-cycle assessment of typical EVSE equipment, including first cost and maintenance and operating costs, it was found that AC Level 1 or 2 workplace charging can be similar to or lower in cost than charging at home. The cost to charge a PEV at home using an AC Level 1 charging station is $1.79 per charging session while charging at work would cost$1.53 if utility demand charges were not part of the electric bill or $1.79 if demand charges were included. Charging the PEV at higher power levels (e.g. AC Level 2 or DC Level 2) can result in much higher costs when charging stations are used only once per day

Analysis Techniques For Evaluating Energy Conservation Programs Using Utility AMI Data

With the evolution of Advanced Metering Infrastructure (AMI) electric meters, utility companies now have direct access to whole building electricity use at a granular time scale. AMI data can be used for a variety of purposes beyond billing, for example, to evaluate the efficacy of energy conservation (EC) programs. Historical methods for calculating EC program savings include building simulation models and laboratory and/or field testing. With big data now available, which analysis methods are more likely to yield quality results? In a recent project, the Orlando Utility Commission provided monitored AMI data from Oct 1, 2015 - Sep 27, 2018 for 2,832 Orange Country, Florida rebate participants. These participants had either already enrolled in a rebate program or had signed up to participate. The project objective was to analyze this large AMI data set to estimate the savings from a heat pump retrofit program in energy (kWh) and coincident peak demand (kW) relative to baseline efficiency levels. This paper illustrates five methods of predicting EC program savings for a utility company\u27s rebate program using: 1) side-by-side groups of current and future participants, 2) before and after evaluation of a stable group of participants, 3) evaluation of a before and after group using pooled regression, 4) regression on individual accounts with results then averaged, and 5) building simulation model results are used as a comparative baseline. This effort was pursued to see if the bias between the various participant segments could be reduced to focus on energy differences within the retrofit equipment itself. This paper was published in the 2020 ACEEE Summer Study on Energy Efficiency in Buildings

Developing Natural Gas Cost Escalation Rates For The Associated Gas Distributors Of Florida

The Florida Solar Energy Center (FSEC) created a spreadsheet tool used to calculate the fuel escalation rates for electricity and natural gas for the previous 5-year and 10-year periods. These escalation rates are calculated at the local, State, and national level for both residential and commercial customers. The previous 5-year and 10-year general inflation rate as determined by the U.S. Department of Labor\u27s Bureau of Labor Statistics consumer price index are also included. These calculations are made in accordance with rules established by the Florida Building Commission pursuant to rule 9B-13.0071, Cost Effectiveness of Amendments to Energy Code

Electric Vehicle Grid Experiments And Analysis

This project developed a low cost building energy management system (EMS) and conducted vehicle-to-grid (V2G) experiments on a commercial office building. The V2G effort included the installation and operation of a Princeton Power System CA-30 bi-directional power system. These experiments targeted the reduction of utility peak electrical demand for a commercial office building. In each case, total building peak demand was managed through a computer algorithm to limit the charging rate of electric vehicles or used the vehicle\u27s on-board traction battery as a storage device to minimize peak electrical loads

REDUCING ENERGY USE IN FLORIDA BUILDINGS

The 2007 Florida Building Code (ICC, 2008) requires building designers and architects to achieve a minimum energy efficiency rating for commercial buildings located throughout Florida. Although the Florida Building Code is strict in the minimum requirements for new construction, several aspects of building construction can be further improved through careful thought and design. This report outlines several energy saving features that can be used to ensure that new buildings meet a new target goal of 85% energy use compared to the 2007 energy code in order to achieve Governor Crist’s executive order to improve the energy code by 15%. To determine if a target goal of 85% building energy use is attainable, a computer simulation study was performed to determine the energy saving features available which are, in most cases, stricter than the current Florida Building Code. The energy savings features include improvements to building envelop, fenestration, lighting and equipment, and HVAC efficiency. The impacts of reducing outside air requirements and employing solar water heating were also investigated. The purpose of the energy saving features described in this document is intended to provide a simple, prescriptive method for reducing energy consumption using the methodology outlined in ASHRAE Standard 90.1 (ASHRAE, 2007). There are two difficulties in trying to achieve savings in non-residential structures. First, there is significant energy use caused by internal loads for people and equipment and it is difficult to use the energy code to achieve savings in this area relative to a baseline. Secondly, the ASHRAE methodology uses some of the same features that are proposed for the new building, so it may be difficult to claim savings for some strategies that will produce savings such as improved ventilation controls, reduced window area, or reduced plug loads simply because the methodology applies those features to the comparison reference building. Several measures to improve the building envelope characteristics were simulated. Simply using the selected envelope measures resulted in savings of less than 10% for all building types. However, if such measures are combined with aggressive lighting reductions and improved efficiency HVAC equipment and controls, a target savings of 15% is easily attainable