Engineering Commons^™

Metal And Flexible Duct Systems Impacts Upon Cooling Energy And Performance, Florida Solar Energy Center, Charles Withers, Jr.

FSEC Energy Research Center®

Flexible duct is commonly used throughout the U.S. in residential construction. It performs well when installed in accordance with industry standards, however, they are often not installed as such. Issues such as not cutting ducts to the exact length needed, and instead using significantly more duct, result in compression and higher static pressure. Poorly supported ducts or turns without proper radius also increase static pressure. A research project was completed to evaluate the differences in performance between a metal duct and flexible duct systems in two side-by-side otherwise identical residential laboratories. Testing evaluated three different flex duct system configurations compared …

Targeting The Best Performing Home Efficiency Programs With Advanced Metering Evaluation Supplemented By Simulation, Florida Solar Energy Center, Robin Vieira

FSEC Energy Research Center®

The authors investigated the impacts of seven residential rebate energy efficiency programs offered by a municipal utility. The evaluation examined energy use pre and post retrofit using the Advanced Mete1ing Infrastructure (AMI) data, disaggregated by major end-use and weather-adjusted; and also by detailed simulations. Residences modeled were representative of typical participants for that measure based on factors such as year built, conditioned square feet and number of bedrooms.

Our analysis found the residential rebate programs to be of highly varied effectiveness, but important differences surfaced between the simulation and the AMI data evaluation. Not surprisingly, programs with larger samples tended …

Residential Attic Performance Comparison Research, Florida Solar Energy Center, Charles Withers, Jr.

FSEC Energy Research Center®

This research project evaluated cooling energy and moisture-related impacts between conventional attic venting and sealed attic vents in a lab home located in central Florida. All tests had R30 insulation on the ceiling and the roof deck uninsulated. A total of four different test configurations were tested. The four tested configurations were: Attic Vented with Attic Ducts, Attic Vents Sealed with Attic Ducts, Attic Vented with Indoor Ducts, and Attic Vents Sealed with Indoor Ducts. On average the impact from sealing attic vents will increase annual cooling energy use in a Florida home between 5%-10%. For a 1620 square foot …

Investigation Of Energy Impacts Of Whole-House Ducted Dehumidifier Location, Florida Solar Energy Center, Charles Withers, Jr.

FSEC Energy Research Center®

This report discusses energy impacts related to how ducted dehumidifier ducts are configured as well as where they are located. Lab controlled testing evaluated three different duct configurations. The three DHU lab test configurations were: 1) DHU air ducted directly from/to room, 2) DHU ducted from/to the central air return duct, and 3) DHU from/to the central air supply duct. Simulation effort evaluated conductive energy gains/losses through dehumidifier and its ducts for 1) conditioned space, 2) attic, and garage locations.

Final Report: Cooling Seasonal Energy And Peak Demand Impacts Of Improved Duct Insulation On Fixed-Capacity (Seer 13) And Variable-Capacity (Seer 22) Heat Pumps, Florida Solar Energy Center, Charles Withers, Jr.

FSEC Energy Research Center®

Previous phase 1, 2, and 3 research identified that duct conductive losses to an attic environment imposed greater relative energy losses for the variable-capacity systems compared to the fixed-capacity systems (Cummings and Withers 2011) because of the longer dwell time of conditioned air in the ducts. The purpose of the Phase 4 experiments reported here was to see if duct R-value enhancement would benefit the overall operating efficiency of the variable-capacity system relatively more than the fixed-capacity system. The current Phase 4 experiments (the primary focus of this report) found that this was a secondary effect.

Cooling And Heating Season Impacts Of Right-Sizing Of Fixed- And Variable-Capacity Heat Pumps With Attic And Indoor Ductwork, Florida Solar Energy Center, James Cummings

FSEC Energy Research Center®

The U.S. Department of Energy's research team Building America Partnership for Advanced Residential Construction implemented two phases of experiments to examine the cooling and heating seasonal and peak demand performance of a variable-capacity 2-ton SEER 22 heat pump versus a 3-ton variable-capacity SEER 21 heat pump with attic ducts and indoor ducts. The experiments also compared the cooling and heating seasonal and peak demand performance of 2-ton versus 3-ton fixed-capacity SEER 13 heat pumps with attic ducts and indoor ducts.

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 …

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, …

Building America Industrialized Housing Partnership, Annual Report -- Budget Period 3, 02/01/08-12/31/0, Florida Solar Energy Center, Subrato Chandra

FSEC Energy Research Center®

This annual report summarizes the work conducted by the Building America Industrialized Housing Partnership (www.baihp.org) for the period 2/1/08 to 12/31/08. BAIHP is led by the Florida Solar Energy Center of the University of Central Florida. In partnership with over 50 factory and site builders, work was performed in two main areas: research and technical assistance.

In the research area we continued laboratory and field testing of interior duct systems to document their expected energy savings of about 20% in heating and cooling. Worked with Building Science Corp. to test an innovative air-conditioner with an extra dehumidification coil in the …

Research Results From A Few Alternate Methods Of Interior Duct Systems In Factory Built Housing Located In The Hot Humid Climate, Florida Solar Energy Center, Neil Moyer

FSEC Energy Research Center®

The U.S. Department of Energy's (DOE) Building America Industrialized Housing Partnership (BAIHP) has collaborated with two of its industry partners to work on a portion of the project that relates to the construction and evaluation of prototype interior duct systems. In 2006, work began on a duct system design that would locate the entire length of duct work within the air and thermal barriers of the envelope. One of these designs incorporated a high-side supply register that connects to the conventional floor duct. The other design utilized a single soffit located within the conditioned space at the marriage line. The …

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.

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

Energy Efficient Renovations Of Storm Damaged Residences - Florida Case Studies, Florida Solar Energy Center, Neil Moyer

FSEC Energy Research Center®

Storm-damaged homes offer the opportunity for repairs that reduce energy use, improve comfort and enhance resistance to future storms. Case studies of four Florida homes damaged in the summer of 2004 were documented to show the costs and benefits of various retrofit strategies. All four homes required roof replacement and each took advantage of roof cladding with higher reflectance than the original, a proven means of reducing cooling energy use. Two of the case studies included improvements to attic insulation, tightening of the envelope and/or duct system and improved efficiency equipment and lighting. Energy savings attributable to storm repairs were …

Unbalanced Return Air In Commercial Buildings, Florida Solar Energy Center, Charles Withers, Jr.

FSEC Energy Research Center®

Research in 88 central Florida commercial buildings during the last decade has found that 26% of the air distribution systems had substantially unbalanced return air. Unbalanced return air occurs when there is a restriction to air flow between the supply discharge and the return air, creating positive and negative pressure fields throughout the building. Severe consequences in commercial buildings can occur as a result of unbalanced air flows. This paper examines unbalanced return air and its consequences in three commercial buildings, and explains why balancing air flow in buildings is a critical part of maintaining a healthy and energy efficient …

Unbalanced Return Air In Residences: Causes, Consequences, And Solutions, Florida Solar Energy Center, James Cummings

FSEC Energy Research Center®

Field research performed in 70 central Florida homes found that return grills are almost always located in the central zone of the house, and that individual rooms rarely have ducted return air or return transfer pathways. When interior doors were closed, the closed rooms went to +0.0249 inches of water gauge (in w.g.) (+6.2 pascals (Pa)) wrt outdoors (wrt = with respect to), and the central zone went to -0.0116 in w.g. (-2.9 Pa) wrt outdoors. Room pressures as high as +0.150 in w.g. (+37.3 Pa) and central zone pressure as low as -0.059 in w.g. (-14.7 Pa) wrt outdoors …

Cold Climate Case Study; High Efficiency North Dakota Twin Homes, Florida Solar Energy Center, David Chasar

FSEC Energy Research Center®

The Eastern Dakota Housing Alliance has completed 8 of 20 planned multi-family and single-family dwellings on Selkirk Circle in Grand Forks, North Dakota. Four twin-home (duplex) units were completed in March of 2003 (Phase I) and four more identical units were completed in February of 2004 (Phase II). Four additional units (Phase III) are due for completion by mid-summer, 2004. Design assistance and performance testing were provided by the Building America Industrialized Housing Project with the goal of achieving up to 50% energy savings over the 1993 Model Energy Code.

To approach this level of savings, various envelope and equipment …

Energy Star Manufactured Homes: The Plant Certification Process, Florida Solar Energy Center, David Chasar

FSEC Energy Research Center®

In an on-going collaboration over the last ten years, researchers have worked with the manufactured housing industry offering building science advice and conducting diagnostic testing (Chandra et al 2002). This partnership resulted in the first two HUD code ENERGY STAR homes in 1997 and the development of standardized, in-plant Duct Blaster testing in 2001. One manufacturer is currently testing duct leakage on every home in 12 factories, representing over 8,000 homes per year.

In 2001, the U.S. Environmental Protection Agency (EPA) introduced the ENERGY STAR label for manufactured homes. Guidelines for this program focus on certification of the HUD-code plant …

Achieving Airtight Ducts In Manufactured Housing, Florida Solar Energy Center, Janet Mcilvaine

FSEC Energy Research Center®

Data and findings presented here were gathered between 1996 and 2003 during 39 factory visits at 24 factories of six HUD Code home manufacturers interested in improving the energy efficiency their homes. Factory observations typically showed that building a tighter duct system was the most cost effective way to improve the product's energy efficiency.

Air Handler Leakage: Field Testing Results In Residences, Florida Solar Energy Center, James Cummings

FSEC Energy Research Center®

Testing was performed to characterize air leakage in 30 air handler cabinets and at connections to supply and return ductwork. Operating pressures were measured in the air handler and plenums. Q 0.1 (Q 25) in the air handler averaged 23.9 cfm (11.3 l/s) in 30 homes. Leakage at the return and supply ductwork connections averaged 3.9 Q 0.1 (1.8 l/s Q 25) and 2.2 Q 0.1 (1.0 l/s Q 25), respectively. Actual return side leakage of 77.5 cfm (36.6 l/s) and supply side leakage of 3.1 cfm (1.5 l/s) are calculated based on Q 0.1 (Q 25) and measured operating …

Measured And Simulated Cooling Performance Comparison; Insulated Concrete Form Versus Frame Construction, Florida Solar Energy Center, David Chasar

FSEC Energy Research Center®

Four occupied homes near Dallas, Texas were monitored to compare cooling energy use. Two homes were built with typical wood frame construction, the other two with insulated concrete form (ICF) construction. Remote data loggers collected hourly readings of indoor and outdoor temperature, relative humidity, furnace runtime fraction, total building electrical energy and HVAC energy use. Data was recorded from January through August 2000.

Analysis of the measured data shows that insulated concrete form (ICF) construction can reduce seasonal cooling energy use 17 - 19% over frame construction in two-story homes in the North Texas climate. This result includes adjustments to …

Design And Construction Of Interior Duct Systems, Florida Solar Energy Center, Janet Mcilvaine

FSEC Energy Research Center®

To combat the energy, durability, and indoor air quality penalties of duct leakage, energy experts have recommended putting the duct system and air handler inside the conditioned space. Two paths of accomplishing this have emerged: unvented attics/crawl spaces and interior chases. This study focuses on the design, construction, and performance of the interior chase approach as implemented by five different builders in Texas, North Carolina, and Florida.

Researchers found that, in many cases, breeches of the air barrier were evident from simple visual inspection. Critical points of design and construction were identified and will be presented through photos, design and …

Performance And Impact From Duct Repair And Ventilation Modifications Of Two Newly Constructed Manufactured Houses Located In A Hot And Humid Climate, Florida Solar Energy Center, Charles Withers, Jr.

FSEC Energy Research Center®

Two nearly identical houses situated next to each other in Bossier City, Louisiana were studied in an effort to better understand moisture and cooling energy related problems in manufactured houses with low thermostat set-points during the cooling season. By design, the major difference between houses was the type of air conditioning units. House A had a standard split air conditioner and House B had a two-speed split air conditioner.

In an effort to make the buildings more similar, the building airtightness was adjusted until it was the same in each house, and duct leaks were sealed so that the ducts …

Ventilation, Humidity, And Energy Impacts Of Uncontrolled Airflow In A Light Commercial Building, Florida Solar Energy Center, Charles Withers, Jr.

FSEC Energy Research Center®

A small commercial building was monitored before and after energy saving retrofits to study the impact of retrofits upon ventilation rates, humidity, building pressure and air conditioning energy use. Duct airtightness testing identified severe duct leakage as a significant source of uncontrolled airflow. Differential pressure and infiltration measurements using tracer gas indicated an attic exhaust fan as another significant source of uncontrolled airflow. Duct repair resulted in a 31% drop (30.5 kWh/day) in cooling energy, and an increase in relative humidity from 72% to 76%. Turning off the attic exhaust resulted in an additional 36% energy savings (14.3 kWh/day), including …

Monitored Summer Peak Attic Air Temperatures In Florida Residences, Florida Solar Energy Center, Danny Parker

FSEC Energy Research Center®

Florida Solar Energy Center (FSEC) has analyzed measured summer attic air temperature data taken for some 21 houses (three with two different roof configurations) over the last several years. The analysis is in support of the calculation within ASHRAE Special Project 152P which will be used to estimate duct system conductance gains which are exposed to the attic space. Knowledge of prevailing attic thermal conditions are critical to the duct heat transfer calculations for estimation of impacts on residential cooling system sizing.

The field data was from a variety of residential monitoring projects which were classified according to intrinsic differences …

Building Cavities Used As Ducts: Air Leakage Characteristics And Impacts In Light Commercial Buildings, Florida Solar Energy Center, James Cummings

FSEC Energy Research Center®

Field testing in 70 small commercial buildings in central Florida identified that building cavities were used as part of the air distribution system in 33 buildings. The various building cavity types (# of buildings in parentheses) are: enclosed air handler support platforms (10), mechanical closets (8), mechanical rooms (6), ceiling spaces (7), wall cavities (6), chases (1), and "other" building cavities (2). Testing found that these building cavities are considerably more leaky than standard ducts and plenums because they are generally not built to the same airtightness standard as ducts. Actual air leakage is a function not only of duct …

Uncontrolled Air Flow In Non-Residential Buildings, Florida Solar Energy Center, James Cummings

FSEC Energy Research Center®

The objective of this study was to develop the capability to substantially reduce energy use, building degradation and indoor air pollution caused by uncontrolled air flow in nonresidential buildings. For purposes of the study, 'uncontrolled air flow' was defined as air moving across the building envelope or between zones or components of a building, where the pathways of flow, the direction of flow, and the origin of the air are unknown, unspecified, or unintended. The study comes to three major conclusions as follows: 1. Uncontrolled air flow is pervasive in buildings, often resulting in severe -- and sometimes even catastrophic …

Energy Savings From Repair Of Uncontrolled Airflow In Eighteen Small Commercial Buildings, Florida Solar Energy Center, Charles Withers, Jr.

FSEC Energy Research Center®

Uncontrolled airflow, including duct leakage, pressure imbalances caused by closed interior doors, and exhaust/intake airflow imbalance, was characterized in 70 commercial buildings. In 18 of these buildings, uncontrolled airflows were repaired and energy savings from these repairs were monitored. In most buildings the retrofit was duct repair. In other cases, outdoor airflow was reduced and return air transfers were provided. Cooling energy use was reduced by an average 15.1% in these 18 buildings. With an average repair cost of $455 and average cooling energy savings of $195 per year, uncontrolled airflow retrofits proved to be very cost-effective. Various factors indicate …

Indoor Air Quality Impacts Of Uncontrolled Air Flow And Depressurization In Eight Commercial Buildings In Central Florida, Florida Solar Energy Center, James Cummings

FSEC Energy Research Center®

Field investigations were done in 68 commercial buildings to identify uncontrolled air flows and pressure imbalances. Results from eight buildings (six restaurants and two sports facilities) are reported in this paper. Testing included building airtightness tests, identification of building air barrier location, duct system airtightness, characterization of pressure differentials, building air flow balance, and infiltration/ventilation rates. Six restaurants and one sports facility were found to operate at negative pressures which ranged from -0.003 inWC (-0.8 Pa) to -0.173 inWC (-43 Pa) and averaged -0.051 inWC (-12.7 Pa) under normal operation. A second sports facility operates partially at positive pressure and …

Investigation Of Air Distribution System Leakage And Its Impacts In Central Florida Homes, Florida Solar Energy Center

FSEC Energy Research Center®

Testing for air leakage in air distribution systems was done in 160 central Florida homes. Tracer gas tests found that infiltration rates were three times greater when the air handler was operating that when it was off, indicating that there are large leaks in the air distribution system. Infiltration averaged 0.91 air changes per hour (ach) with the air handler (AH) operating continuously and 0.28 ach with the AH off. Return leaks were measured by tracer gas and found to average 10.7% of AH total flow. House airtightness, in 99 of these homes, determined by blower door testing, averaged 12.7 …

Impacts Of Duct Leakage On Infiltration Rates, Space Conditioning Energy Use, And Peak Electrical Demand In Florida Homes, Florida Solar Energy Center, James Cummings

FSEC Energy Research Center®

Testing for duct leakage was done in 91 homes. Tracer gas tests found that infiltration rates were four times greater when the air handler was operating than when it was off. Return leaks were found to average 10.0% of air handler total flow. House airtightness, in 63 of these homes, determined by blower door testing, averaged 12.38 air changes per hour at 50 Pascals (ACH50). When the duct registers were sealed, ACH50 decreased to 10.93, indicating that 11.7% of the house leaks were in the duct system.

Duct repairs were made on 25 homes. Blower door tests found 12.30 air …