Engineering Commons^™

Changing Climates And Extreme Weather For Minnesota, Patrick A. Tebbe

Mechanical and Civil Engineering Department Publications

Climate change is impacting the design, prediction, and operation of HVAC systems for the built environment, and will continue to do so for the foreseeable future. This presentation reviews climate predictions for the upper Midwest and how they will affect the HVAC industry. Topics such as changing design conditions, extreme weather impact, and increased electrification will be addressed.

Investigation Of The Prevalence Of Faults In The Heating, Ventilation, And Air-Conditioning Systems Of Commercial Buildings, Amir Ebrahimifakhar

Durham School of Architectural Engineering and Construction: Dissertations, Thesis, and Student Research

This dissertation describes a large-scale investigation of heating, ventilation, and air-conditioning (HVAC) fault prevalence in commercial buildings in the United States. A multi-year dataset with 36,556 pieces of HVAC equipment including air handling units (AHUs), air terminal units (ATUs), and packaged rooftop units (RTUs) was analyzed to determine values for several HVAC fault prevalence metrics. The primary source of data for this study comes from three commercial fault detection and diagnostics (FDD) providers. Since each FDD provider uses different terms to refer to the same fault in an HVAC system, a mapping function was created for each FDD provider’s dataset, …

Lab Home Testing Of Residential Isolation Space Control To Minimize Infectious Disease Transmission In Existing Single-Family Homes, Florida Solar Energy Center, Tanvir Khan

FSEC Energy Research Center®

Existing evidence strongly suggests that viral infectious diseases can be transmitted via an airborne route across distances in indoor environments. Accordingly, the risk of airborne transmission within homes should be managed. The public health emergency associated with SARS-CoV-2 makes controlling airborne transmission of respired viruses in indoor environments critical, especially in poorly ventilated indoor environments. The effectiveness of engineering interventions requiring minor efforts that create a negative-pressure isolation zone (IZ) for a contagious person has yet to be tested for existing residential homes.

To mitigate the risk of airborne virus transmission and maximize health protection for the population in existing …

Lab Home Testing Of Residential Isolation Space Control To Minimize Infectious Disease Transmission In Existing Single-Family Homes -- Fact Sheet, Florida Solar Energy Center, Tanvir Khan

FSEC Energy Research Center®

The FSEC Energy Research Center at the University of Central Florida performed research to test the effectiveness of interventions to isolate an ill person recovering from a contagious disease in a single-family home from the rest of the occupants in the home. Focus was placed on interventions requiring minor cost and effort on the part of the occupants.

DOE/GO-102021-5537, https://www.nrel.gov/docs/fy21osti/79519.pdf

Who's Leading: The Dance Between Mini-Splits And Existing Hvac Systems, Florida Solar Energy Center, Cheryn Metzger

FSEC Energy Research Center®

Recently, many utilities across the U.S. have provided incentives for ductless mini-split heat pumps due to their relatively high efficiencies. However, when these ductless mini-splits are installed in existing homes, utilities and researchers find that they are not living up to their energy saving potential, due to a lack of coordinated controls with the existing HVAC system. The Pacific Northwest National Laboratory (PNNL), the Florida Solar Energy Center (FSEC), and The Levy Partnership are all leading projects across the country to address this problem. The goal for this body of work is to determine which control strategies provide the most …

Evaluating Moisture Control Of Variable-Capacity Heat Pumps In Mechanically Ventilated, Low-Load Homes In Climate Zone 2a, Florida Solar Energy Center, Eric Martin

FSEC Energy Research Center®

The well-sealed, highly insulated building enclosures constructed by today's home building industry coupled with efficient lighting and appliances are achieving significantly reduced heating and cooling loads. These low-load homes can present a challenge when selecting appropriate space-conditioning equipment. Conventional, fixed-capacity heating and cooling equipment is often oversized for small homes, causing increased first costs and operating costs. Even if fixed-capacity equipment can be properly specified for peak loads, it remains oversized for use during much of the year. During these part-load cooling hours, oversized equipment meets the target dry-bulb temperatures very quickly, often without sufficient opportunity for moisture control. The …

Design Of An Very High Efficiency Evaporatively Cooled Mini-Split Air Conditioner, Florida Solar Energy Center, Danny Parker

FSEC Energy Research Center®

An in-house research project at the Florida Solar Energy Center in 2013 was conducted to evaluate the potential of an evaporatively cooled mini-split heat pump. The mini-split heat pump modified was a 1.5-ton Fujitsu model with 19.2 SEER and 10.0 HSPF energy efficiency ratings. Cooling capacity of the system is variable and ranges from 7,000 to 23,000 Btu/h.

We demonstrated that it is possible to improve the energy efficiency of the evaluated mini-split air conditioner by 21% seasonally in Florida's humid climate using an evaporative pre-cooler. Further, we showed the same apparatus was able to improve air conditioner efficiency by …

Investigation Of Potential Benefits Of Revising Exception 1 Under Florida Building Code, Energy Conservation, Section 101.4.7.1.1 Duct Sealing Upon Equipment Replacement, Florida Solar Energy Center, Janet Mcilvaine

FSEC Energy Research Center®

Section 101.4.7.1.1, Duct sealing upon equipment replacement (Mandatory), of the 2012 Supplement to the Florida Building Code, Energy Conservation went into effect briefly in 2013. The new section required sealing of accessible ducts at the time of HVAC equipment replacement. Exception #1 however, eliminates the requirement for ducts in conditioned space, and by doing so, effectively eliminates the sealing requirement for building cavities in conditioned space that are used as air distribution paths. However, test results show that these building cavities are often connected to adjacent unconditioned spaces, in effect they are not really in the conditioned space because they …

Initial Testing Of A Unitary Hvac System Advanced Control Module, Florida Solar Energy Center, Richard Raustad

FSEC Energy Research Center®

Testing of a unitary HVAC system advanced control module and the results.

Technical Subtopic 2.1: Modeling Variable Refrigerant Flow Heat Pump And Heat Recovery Equipment In Energyplus, Florida Solar Energy Center, Richard Raustad

FSEC Energy Research Center®

The University of Central Florida/Florida Solar Energy Center, in cooperation with the Electric Power Research Institute and several variable-refrigerant-flow air conditioning (VRF AC) manufacturers, provided a detailed computer model for a VRF AC system in the United States Department of Energy's (U.S. DOE) EnergyPlus' building energy simulation tool. No other simulation tool currently has the capability to accurately model this state-of-the-art VRF heating, ventilating, and air conditioning (HVAC) equipment. Detailed laboratory testing and field demonstrations were performed to measure equipment performance and compare this performance with that predicted by the use of this new model through computer simulation.

This project …

Managing The Drivers Of Airflow And Water Vapor Transport In Existing Single-Family Homes (Revised), Florida Solar Energy Center, James Cummings

FSEC Energy Research Center®

Air and water vapor are transported into and within single-family homes as a result of pathways and driving forces. Without pathways, no air or water vapor transport could occur. Likewise, without driving forces, little or no air or water vapor transport will occur. Homes always have pathways and driving forces. This report focuses on managing the driving forces that move air and water vapor across the building envelope.

A Virtual Supply Airflow Rate Meter In Rooftop Air Conditioning Units, Daihong Yu

Durham School of Architectural Engineering and Construction: Dissertations, Thesis, and Student Research

Virtual sensing technology aims to estimate difficult to measure, expensive, or new quantities by using multifarious mathematical models along with non-invasive and low-cost measurements. Such embedded intelligence is a key to improving the performance of building systems in terms of functionality, safety, energy efficiency, environmental impacts, and costs. Considering the progress that has been achieved over many various fields (e.g., process controls, automobiles, avionics, autonomous robots, telemedicine) within the last two decades, numerous intelligent features have been incorporated and enabled that would otherwise not be possible or economical.

To identify the potential opportunities and research/development needs of virtual sensing technology …

Short-Term Curtailment Of Hvac Loads - Executive Summary, Florida Solar Energy Center, Lixing Gu

FSEC Energy Research Center®

Rapidly increasing requirements placed on utilities to reduce peak loads has led to utility customer incentives to shift peak demand to non-peak times or reduce peak loads when notified by the utility that the grid is close to capacity. This study investigates methods used to reduce building demand during a fixed time window near a utilities on-peak period. The window was chosen to be 5-9 A.M. in winter and 2-5 P.M. in summer.The most common methods for reducing building peak demand were reviewed and categorized by their usefulness and wide-spread availability. These strategies were reductions in lighting power density, global …

Field Monitoring And Hourly Simulation Of Energy And Demand Savings From Use Of The Telkonet Ss5000 System Hotel Ac Occupancy Control, Florida Solar Energy Center, James Cummings

FSEC Energy Research Center®

Air conditioning and heating control systems were installed in a 56-room hotel in central Florida. Thermostat setpoints in half of the rooms were adjusted when the room was detected to be unoccupied. Heating and cooling energy use was monitored for a period of 9.5 months. Energy and demand savings were analyzed.

Building America Industrialized Housing Partnership (Baihp Ii), Annual Report - Budget Period 4 (Bp4), January 01, 2009 - December 31, 2009, Florida Solar Energy Center, Robert Abernethy

FSEC Energy Research Center®

This annual report summarizes the work conducted by the Building America Industrialized Housing Partnership (BAIHP - www.baihp.org) during the fourth budget period (BP4) of our contract, January 1, 2009 to December 31, 2009. Progress from the three previous budget periods is included for context.

BAIHP is led by the Florida Solar Energy Center (FSEC) of the University of Central Florida. With over 50 Industry Partners including factory and site builders, work was performed in four task areas:

• Task 1: System Evaluations
• Task 2: Prototype House Evaluations
• Task 3: Community Scale Evaluations
• Task 4: Post- Phase 3 Activities.

In Task 1, …

Comparison Of The Energygauge Usa And Beopt Building Energy Simulation Programs, Florida Solar Energy Center, Danny Parker

FSEC Energy Research Center®

Two hourly energy simulation software, BEopt and Energy Gauge USA, were compared to ensure accuracy and evaluate agreement on the impact of various energy efficiency improvements. Within the Building America program, these software aid design teams working toward the U.S. Department of Energy's goal to make Zero Energy Homes economically viable by 2025. Builders use the software to achieve the extensive energy savings (70%-80%) from various measures before adding solar electric power generation. The study found that in general, BEopt and EnergyGauge USA agree fairly well on the impact of energy efficiency improvements, while identifying several discrepancies that need further …

Top 10 Checklist - Energy-Efficient Buildings For The Southern United States, Florida Solar Energy Center, James Cummings

FSEC Energy Research Center®

The following Top Ten Checklist provides recommendations for creating energy efficient commercial buildings in areas with hot and humid summers. Commercial and institutional buildings vary greatly, from one to another, in size, use, and type of construction. For purposes of this Top Ten Checklist we are assuming a medium-sized (20,000 to 50,000 ft²) office building located in areas with hot and humid summers. The issues that are raised here may equally apply to schools, churches, theaters, and some retail buildings.

Assessment Of The Effectiveness And Energy Efficiency Of Humidity Control Approaches In Vacant Florida Homes, Florida Solar Energy Center, James Cummings

FSEC Energy Research Center®

In a hot and humid climate such as Florida, 'snowbirds' that leave their homes for extended summer periods need guidance on effective and energy efficient methods of humidity control. Experiments were performed in seven residences to evaluate various approaches to humidity control, including providing no mechanical system control. A humidity target was identified to maintain indoor relative humidity (RH) at 65% or lower most of the time. Providing no mechanical conditioning (letting the building 'float') yields relative humidity at 65% or below during hot and sunny weather in some homes, but not during cloudy weather. Setting the AC system thermostat …

Ac System Equipment Specification, Installation And Operational Options For Improved Indoor Humidity Control, Florida Solar Energy Center, Don B. Shirey Iii

FSEC Energy Research Center®

High-efficiency home designs have significantly reduced sensible cooling loads, and some building codes and IAQ standards have begun requiring continuous outdoor ventilation air. These trends have led to an increased prevalence of high indoor humidity conditions (Rudd and Henderson 2007). This paper presents a summary of low-cost or no-cost equipment selection and operation options for conventional residential air-conditioning equipment than can result in lower indoor humidity levels. These options should be evaluated and employed to the extent possible prior to considering the added first cost and operating costs of separate dehumidification equipment.

Case Study Of An Innovative Hvac System With Integral Dehumidifier, Florida Solar Energy Center, Richard Raustad

FSEC Energy Research Center®

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 …

Ac System Equipment Specification, Installation And Operational Issues That Can Enhance Indoor Humidity Control, Florida Solar Energy Center, Don B. Shirey Iii

FSEC Energy Research Center®

This report presents summary of research on equipment selection and operation issues with conventional air conditioning equipment that can be employed prior to seeking the added first cost and operating cost of separate dehumidifiers.

Closing The Gap: Getting Full Performance From Residential Central Air Conditioners. Task 4.2-Develop New Climate-Sensitive Air Conditioner, Design, Construction, And Testing., Florida Solar Energy Center, Don B. Shirey Iii

FSEC Energy Research Center®

This study evaluated the performance of a prototype air conditioning system. The configuration of the prototype was based on detailed simulation results performed as part of this study. The results of the previously completed simulation indicated that energy-efficient, properly-ventilated homes in humid climates need equipment options or configurations that can provide a modest amount of additional dehumidification capacity while coordinating their operation with conventional cooling and ventilation systems. A prototype air conditioning system was constructed using currently available components and provides a method to independently control sensible (temperature) and latent (moisture) building loads. The prototype system was tested in both …

Airflow Network Modeling In Energyplus, Florida Solar Energy Center, Lixing Gu

FSEC Energy Research Center®

The airflow network model in EnergyPlus provides the ability to simulate multizone wind-driven airflows. The model is also able to simulate the impacts of forced air distribution systems, including supply and return air leaks. The air distribution system portion of the model is currently applicable for constant-air-volume systems. Future enhancements will include adding hybrid ventilation control and possible extension to include variable-air-volume distribution systems.

This paper describes the input objects, calculation procedures, model validation, and example results. The model inputs consist of five main objects: simulation control, multizone data, node data, component data, and linkage data. The model calculates pressure …

Closing The Gap: Getting Full Performance From Residential Central Air Conditioners, Task 4 - Develop New Climate-Sensitive Air Conditioner, Simulation Results And Cost Benefit Analysis, Florida Solar Energy Center, Hugh Henderson, Jr.

FSEC Energy Research Center®

This study evaluated the impacts of conventional and advanced cooling and dehumidification equipment on residential indoor humidity levels and annual energy consumption using whole building computer simulations. The life-cycle cost premium for the various advanced systems was also estimated. Building models were developed for a standard HERS Reference house, meant to represent current residential construction practice, and a High-Efficiency house that would likely qualify for a federal tax credit. The different houses were simulated in seven southeastern U.S. cities and with two ventilation/infiltration scenarios: 1) variable or natural infiltration alone, and 2) mechanical ventilation that complied with ASHRAE Standard 62.2-2004. …

Mitigating The Impacts Of Uncontrolled Air Flow On Indoor Environmental Quality And Energy Demand In Non-Residential Buildings, Florida Solar Energy Center, Hugh Henderson, Jr.

FSEC Energy Research Center®

This project builds on previous field research in Florida that has demonstrated the significant impact that uncontrolled air flows (UAFs) have on indoor environmental quality (IEQ) and energy use in small commercial buildings, a large but poorly understood segment of the nation's building stock. The goal of this project was to extend that research to a national scale by assessing the importance of UAFs in a sample of 25 commercial buildings in New York State. The differences in climate and construction techniques between New York and Florida are expected to bound the range conditions typically found on a national basis. …

Priorities For Energy Efficiency For Home Construction In Florida, Florida Solar Energy Center, Robin Vieira

FSEC Energy Research Center®

Below we provide the priorities for obtaining an energy efficient building in Florida.

Experimental Evaluation Of Nightcool Nocturnal Radiation Cooling Concept: Performance Assessment In Scale Test Buildings, Florida Solar Energy Center, Danny Parker

FSEC Energy Research Center®

An experimental test evaluation has been conducted of a night sky cooling system designed to substantially reduce space cooling needs in homes in North American climates. The system uses a sealed attic covered by a highly conductive metal roof (a roof integrated radiator) which is selectively linked by air flow to the main zone with the attic zone to provide cooling- largely during nighttime hours. Available house mass is used to store sensible cooling. Additional dehumidification is done during the evening hours as warranted by interior conditions.

A previous report describes a detailed simulation model of the relevant night cooling …

Balanced Return Air, Duct Airtightness, And Combustion/Dilution Air Code Compliance In 40 Central Florida Homes, Florida Solar Energy Center, James Cummings

FSEC Energy Research Center®

This report has been extracted from a larger report titled "Florida Building Code - Enhance Florida's Building to Next-Generation Energy & Mechanical Codes and Enrich Compliance", FSEC-CR-1678-06, November 29, 2006, which can be found at http://www.fsec.ucf.edu/en/publications/pdf/FSEC-CR-1678-06.pdf

Measured Impacts Of Proper Air Conditioning Sizing In Four Florida Case Study Homes, Florida Solar Energy Center, Jeffrey Sonne

FSEC Energy Research Center®

Previous studies have shown that residential air-conditioning system oversizing is a common practice that has both energy and comfort penalties. A Florida Power and Light / Florida Solar Energy Center (FSEC) study involving over 350 homes found that 50% of the studies AC systems were over sized by 120% or more (James et al. 1997). The same study found oversizing AC systems by 1.0 to 1.2 times Manual J resulted in 3.7% higher cooling energy use and oversizing systems 1.2 to 1.5 times Manual J resulted in 9.3% higher cooling energy use.

The goal of Task 3.2, Benefits of Proper …

Comparison Matrix Of Florida Residential Building Energy Code And The International Energy Conservation Code (Iecc) 2006, Florida Solar Energy Center, Mangesh Basarkar

FSEC Energy Research Center®

This report presents a comparison of the differences between the Florida and the IECC (2006) residential energy code requirements. In addition to this summary, the documentation is divided into three sets of distinct comparisons: Comparison of Performance-based methods, Comparison of Prescriptive methods and Comparison of key provisions of the texts. In order to provide the best housing stock, with a code that is easy to implement and enforce, the final recommendation of the study was for Florida to maintain its own code, but consider incorporating some of the newer IECC measures.