how infrared thermography drives building energy ... inframation presentation.pdfthermography...

InfraMation 2010 Proceedings 2010-230 Jakovac

How Infrared Thermography Drives Building Energy

Conservation Retrofit Techniques David L. Jakovac, PE FDJ Engineering & Construction, PC

ABSTRACT

Infrared thermography, combined with air barrier test data processed by an experienced and certified American Society for Non-Destructive Testing (ASNT) thermographer, can provide critical information about a building’s sources of energy loss. IR thermography in concert with air barrier testing data can provide quantifiable results to select cost-effective retrofit techniques and certify levels of building air tightness and energy conservation. There are billions of federal and state funding dollars available to fix existing residential housing. This study will present the effect of differences in building insulation and air sealants by performing air change testing utilizing ASTM E-779 standard with thermography for three structures less than 5 years old, and one structure over 40 years old. The scope of energy retrofit - IECC ResCheck energy code compliance evaluation was performed. In addition, the utility company, Idaho Power Company, provided energy consumption, heating degree days (HDD), and charts to assist with the evaluation. Infrared (IR) thermography enhances the contractor’s ability to estimate the building energy conservation retrofit cost and the subsequent payback period. This infrared thermography case study evaluates both insulation and air barrier retrofit techniques for energy conservation of existing residential structures. The study depicts how to quantify the energy conservation effects of window replacements, concrete foundation thermal breaks, and attic and wall envelope sealants. Some energy retrofit techniques result in substantial energy savings, in addition to making a more accurate evaluation of property value possible during ownership conveyance. The study focused on how buildings of approximately 1,500 to 2,200 square feet with central electric or gas heating systems, and eight or more air changes per hour, could achieve the most cost-effective energy retrofit. This study produced a limited hierarchy of energy conservation actions that can mitigate building and energy code deficiencies.

INTRODUCTION

Use of infrared (IR) thermography to develop a hierarchy of energy conservation retrofits gives property owners, managers, and tenants tools they can use to better define tasks and estimate the energy conservation retrofit costs in order to determine the payback or savings to investment ratio (SIR), as shown in Figure 1. The energy audit support data typically suggests multiple retrofit construction upgrades for a single building. The objective of this study was to establish the list of critical information and data needed to determine the optimal conservation tasks regardless of building age and code status. The results have not been applied outside of the study region in Idaho. The scientific data obtained can be used to prioritize actions for the most effective thermal boundary retrofits and new construction techniques in similar climatic regions. The summary of the code and energy conservation construction areas include attic insulation, wall insulation, floor/foundation insulation, window replacement, mechanical system retrofit, high efficiency heating units, and electric water heaters combined to create a comfortable work or living space. A typical energy analysis spreadsheet can assist you with evaluations of energy retrofit options as shown in figure 1 below.


Figure 1. The Boise office conversion energy audit consumption with ResCheck estimate and actual savings from hard data.

WHY USE THERMAL TECHNOLOGY

IR thermography technology was of vital importance in highlighting the energy conservation recommendations for all of the house structures in this report. It clearly showed the areas that lacked insulation and air barriers, areas where convection heat transfer was prevalent, missing thermal boundary definition, improper duct connections, areas of condensation, and numerous construction defects. Moreover, IR thermography helped locate the source of air and water leaks, find multiple areas of energy loss, define the magnitude of suspect areas for cost estimating, revealed poor roof designs, and identified building shell areas lacking proper coordination of the construction trades and/or inadequate design details and specifications. IR can be one of the most cost-effective tools a “whole building” energy auditor can use to determine the best options for energy efficiency, regardless of building age, code status, or condition. IR can be used to provide important energy loss data in both a qualitative and quantitative manner for the building shell integrity, ∆T, comfort, and health issues. IR expedites the identification of building shell and thermal boundary areas of concern. IR is a particularly important tool to find the primary sources of energy loss and waste. Moreover, IR scans can provide critical information if used in concert with other testing devices (e.g. air doors, duct leak detectors, ventilation gauges, temperature, and dew point data equipment.) Effective use of IR thermography provides quantitative data for energy audit evaluation, but it takes a qualified thermographer capable of detailed analysis. Building energy retrofits can be the biggest source of return in the current economy. Very efficient buildings can be built in the future to mitigate our local, national, and world energy disparity and hydrocarbon resource dependency. However, even with the use of energy “modeling,” “commissioning,” “innovative design,” and tightly controlled construction, energy loss will still occur. IR scans can be used to validate the effectiveness and efficiency of the chosen energy conservation retrofit improvements until hard energy consumption data has been accumulated and analyzed, as shown in Figures 2 and 3. IR scans combined with air barrier testing quickly and easily reveal where we need to change the thermal boundary and enhance the building shell.


Figure 2. The Boise office energy consumption chart – 27 month period

Figure 3. Energy usage v. Heating Degree Days (HDD) for heating and cooling.


The primary energy conservation goals that our engineers and energy auditors have set for our customers include the following:

• Secure resources to financially sustain the building for its intended purpose. • Provide excellent indoor air quality. • Create a comfortable indoor environment. • Implement the energy conservation improvements that produce payback in the shortest amount of

time.

CASE STUDIES: This study includes residences constructed over a wide timeline between 1960 and 2008. Figure 4, left, shows a visible image of a common exterior configuration; the IR photo on the right shows the same home in thermal. IR thermography can help isolate major air leaks and other conditions that need retrofitting. Thermal imaging is key in making the energy conservation investments that provide the largest return or best “bang for the buck”.

Figure 4. Residential building construction between 2003 and 2005.

The oldest building to be studied was a 1960-vintage “stick built” rambler-style residence, which had been converted to a professional business office in 1999 (Figures 5 and 6). Energy retrofit evaluations must consider a number of factors, including the physical structure itself, accessibility to building shell cavities within the thermal boundary, the condition of the air and thermal barrier, the materials available to improve energy efficiency, and the desired return on investment. A section in the overall retrofit recommendation containing thermal information on the building can help the client actually see the areas that need improvement as well as serving as a scope of work estimate for subcontractors who take on the project,

Figure 5. Boise office conversion. Original construction 1960 and conversion in 1999.


This study also evaluates the energy performance of similar constructions with varying thermal barrier styles. Two of the three units studied are actually in substantial conformance with the 2003 International Energy Code, but have air leaks that we were able to find using air door depressurization and IR thermography. (See Figures 7 and 8.)

Figure 6. Boise office conversion wall cross-section with energy improvement locations and type.

Old houses may not always be viable candidates for energy efficiency upgrades, regardless of how many times you perform infrared scans or standard building energy assessments in accordance with the “cash for caulking” or Building Performance Institute (BPI) programs, due to financial constraints. The energy audit results may show that the building needs to have energy retrofit upgrades, but in some cases the a payback period may take as many 5 or 10 years as shown in Figure 1. Energy improvements may not be financially viable when a building is at or near the end of its life. IR scans and building assessments can provide quick and effective data regarding an older structure’s suitability for further financial investment, grant subsidies, and/or tax relief. As shown in Figure 1, the most viable energy improvement is most often the window upgrade. This provided an estimated savings of 25% on energy consumption per ResCheck, with the actual savings at 23% through the summer cycle. Note that the air changes through testing, in accordance with ASTM E779, reduced from 21.45 to 14.66 (31%) air changes per hour at CFM50. IR and air leak tests in the Boise office building confirmed that the window seals had been compromised. However, insulation upgrades would not payback for 10 to 13 years. Therefore, it was not financially attractive for a building owner to perform energy conservation improvements unless the building shell, interior air quality (IAQ) or comfort level were compromised, or if there was the potential for equipment failures. Additionally, it was determined that in order to meet the current recheck standards, all of the energy conservation upgrades would be have to be performed which was certainly not financially viable.


The study also surveyed two buildings constructed 2004-2005 that were supposed to be in compliance with the 2003 IECC and IRC building and energy codes. The first of these buildings exhibited significant variations in the thermal barrier resulting in substantial differences in the size and thickness of the thermal boundary. The other building was not constructed in compliance with applicable building codes and performed the worst in energy efficiency and had the highest utility/operation costs. IR scans and ASTM E-779 air provided data to identify the location and cause of the key energy losses related to the building shell, including the following:

• The attic bath fan and HVAC duct were not sealed at the ceiling interface and were exposed to outside air above the thermal barrier.

• Insulated caps (IC) on the can lights in vaulted ceiling areas were omitted. • Air block around the chimney chase was lacking. • Leaks were found around doors and failed window glazing. • An isolation break of appropriate foam insulation between basement perimeter foundation and

concrete slab on grade was missing. IR photos of some of these deficiencies are included in Figures 7 and 8. These structures as designed and constructed would not pass applicable IECC code or US Department of Energy (DOE) ResCheck.

Figure 7. Ceiling insulation problem Figure 8. Basement SOG/perimeter foundation

Three primary administrative and technical shortfalls occurred in the construction of this multiple building development that resulted in non-compliant ResCheck code homes, including: errant calculations submitted to the city plan review, a lack of ResCheck knowledge, and an understaffed inspection agency. The owners bear the burden of making the required physical improvements to correct deficiencies in design and construction, as well as making the necessary energy improvements to meet code compliance and upgrades. The recommended energy retrofit proposed to replace the compromised fiberglass insulation in the attic, define the thermal boundary in the attic, and repair fenestrations due to excessive ice damming. To date, the energy efficiency improvements for the building shell and central heating system have are acknowledged as necessary, but the due to the cost can only be implemented pending successful litigation. Theoretically, based on ResCheck insulation improvements, even without the air tightness improvements in the building’s attic thermal boundary, energy consumption savings were estimated to be $103 per year. Note the air leaks for Energy Seal retrofit were reduced from 7.7 to 5.7 air changes per hour at CFM50, or by 26% as shown in Figure 9. The recommendations for this particular energy retrofit were driven by the needed repairs to the building shell, namely the roof, which was compromised due to ice damming. The attic


insulation and sealant retrofit averaged $5,800 per unit for approximately 780 square feet. It was recommended, after successful litigation, the balance of funds be earmarked to restore additional compromised building shell areas and to help with the anticipated increased maintenance costs. ResCheck does not allow for air barrier improvements as shown in Figure 10, however, changes to the IECC are anticipated in 2010.

Figure 9. Air leak test results and estimated yearly energy cost savings using ResCheck formulas.

Figure 10. ASTM E779 air leak test results, similar buildings, Attic R-50 ResCheck, marvs insulation vs.energy seal.

Interviews with the building’s occupants, and the use of thermography, revealed that the houses featured perimeter foundation insulation and insulation under the concrete slab on grade for living space adjacent to a garage. The lack of proper insulation and a perimeter foundation thermal break was later validated by


destructive inspection. One problem area, identified as a design omission and construction defect, would result in over $1.3 million in energy costs over a 30 year period for a multiple-unit townhouse complex. The lack of a thermal barrier at the concrete foundation and at the slab on grade connection has resulted in ∆T of 12 to 21˚F, (Figure 11) creating an uncomfortable living space during the winter, and increased energy consumption that are clearly illustrated in the IR photo in Figure 12. The repairs were cost-prohibitive, so the installation of an electric unit heater was deemed to be the lesser of the two evils. As a result of the ice damming (Figure 13) and attic condensation, the roof membrane has been compromised in some areas, with loss of life cycle usefulness in other areas. The cost of re-roofing and energy conservation retrofits are part of the ongoing litigation, but are not addressed in this report.

Figure 11. Basement exterior wall Figure 12. Exterior in winter Figure 13. Ice dam

The study surveyed multiple structures built over the past 40 years to different building codes, and in some case perhaps without building code requirements in rural areas. We found that making cost-effective changes to the building shell and operational components in order to support comfort, health, and sustainability can create an economic conundrum for owners, tenants, or property management who cannot financially justify the costs of repairs. It can be especially frustrating for owners of newer buildings that do not meet the applicable building or IECC codes or that do not have the energy efficiency, air quality, or comfort that they assumed were included in their purchase. The building in Figures 14 and 15 was built very recently - 2008. And yet, the building shell, as revealed in the IR images gathered along with other data in a 2.5-hour assessment, has a disappointing number of deficiencies.

Figure 14. Building shell water infiltration. Multiple roof lines and intersections can cause leaks.

Figure 15. Roof leaks into kitchen. Beam pocket has water from a change in roof slope.


CONCLUSIONS

IR scans cannot solve all energy conservation issues, design and construction problems. Some structures are destined, with good reason, to be demolished. Retrofits with highly efficient HVAC life-cycles that will last for 35 years may not only cost too much, they may actually outlive the structure. Cost-effective energy conservation repairs may not coexist amicably with personal finances. Green “whole building” retrofits require financial support, sacrifice, and commitment to energy conservation, quality of life, and community. The federal government assistance program for investment property and principal residence facilitates new construction, but energy improvement retrofits have an equal right to financial assistance and owners need to make the investment in energy upgrades. As we wait for Congress to ratify legislation and provide this financial assistance, our unemployment remains historically high and our system of checks and balances has produced a multi-billion dollar problem that we could face indefinitely. Moreover, it is the opinion of the author that “cash for caulking” limited funding will benefit a relative few before the limited funding runs out. At that point, energy upgrade decisions will finally turn to “back to the future” maintenance programs and finally move to replace defective materials or equipment. The construction industry needs to implement default IR scans for structures in order to provide individual and institutional financial protection. A potential solution has been adopted by local jurisdictions (i.e. Austin, TX). The building seller and the buyer both benefit from IR scans performed by qualified thermographers. The IR scans provide both parties, as well as the lending institution, with improved clarity and risk assessment of potential building issues. This information promotes fair value exchange and can provide valuable information in the unfortunate possibility of a lawsuit down the road. If not the federal government, the real estate commissions for each state should implement the IR scan requirement for all property conveyances similar to house inspectors program. It is fast and efficient, with survey cost that can be shared by the buyer and seller.


ACKNOWLEDGEMENTS

I would like to thank the ITC, FDJ Engineering and Construction, and my PC colleagues for their support. I would also like to thank Ron Lucier for the outstanding Level II training.

AUTHOR

David L. Jakovac is registered Professional Engineer in multiple intermountain states, a Level II Certified Thermographer, an LEED Green Associate, and a BPI-Certified Building Analyst Professional. In 1989, he founded FDJ Engineering and Construction, PC and has over 33 years of construction and engineering experience in building design and construction. He specializes in high-elevation building developments, and has appeared as an expert witness on over 800 cases. David was a 2009 InfraMation presenter, and served as a member of the Building Science discussion panel. He has authored several professional documents in the field of forensic engineering and building energy conservation and sustainability.

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