Energy Analysis for Internal and External Window Film Applications for Existing Homes in Florida

Transcription

1 Energy & Environmental Solutions Energy Analysis for Internal and External Window Film Applications for Existing Homes in Florida PREPARED FOR: INTERNATIONAL WINDOW FILM ASSOCIATION P.O. BOX 3871 MARTINSVILLE, VA PREPARED BY: CONSOL 5757 PACIFIC AVENUE, SUITE 220 STOCKTON, CA TEL: (209) / FAX: (209) CONTACT: MIKE HODGSON DATE: APRIL 24, 2014

2 TABLE OF CONTENTS PURPOSE OF THIS STUDY/ SCOPE... 2 BACKGROUND... 2 ENERGY ANALYSIS... 3 RESULTS... 8 CONCLUSIONS LIST OF FIGURES Figure 1: Future Electricity Consumption Met with Energy Efficiency and Renewable Energy Resources... 2 Figure 2: Residential Retrofits Window Film, Savings per Cost for Energy Measures Miami... 8 Figure 3: Residential Retrofits Window Film, Savings per Cost for Energy Measures West Palm Beach... 9 Figure 4: Residential Retrofits Window Film, Savings per Cost for Energy Measures Tampa.. 9 Figure 5: Residential Retrofits Window Film, Savings per Cost for Energy Measures Jacksonville LIST OF TABLES Table 1: Florida Energy Code Requirements... 5 Table 2: Heating and Cooling Degree Days... 6 Table 3: Properties of Windows Studied for the Internal Film... 6 Table 4: Properties of Windows Studied for the External Film... 7 Table 5: Simple Payback for Internal Window Film Table 6: Simple Payback for External Window Film

3 Purpose of This Study/ Scope The purpose of this study is to determine the cost- effectiveness of internally and externally applied window films when applied to existing Florida homes. If cost effective, window films should be promulgated in energy conservation and peak demand reduction efforts and utility incentive programs in the state of Florida. Background Florida is one of the largest economies and fastest growing states in the country. The state s electricity demand is growing faster than the state s population. 1 Florida needs to determine reliable energy sources to maintain this growth and address the challenge of peak demand. The recent American Council for an Energy- Efficient Economy (ACEEE) report, Potential for Energy Efficiency and Renewable Energy to Meet Florida s Growing Energy Demands, determined that the state could reduce the projected energy use by 29% over the next fifteen years with two- thirds of that reduction coming from energy efficiency. These savings should come from improving energy efficiency in existing private and public buildings, more stringent energy codes, utility incentive programs, appliance and equipment standards, and encouraging advances in building construction. As illustrated in Figure 1 below, the majority of the projected savings comes from energy efficiency. Figure 1: Future Electricity Consumption Met with Energy Efficiency and Renewable Energy Resources 2 1 Potential for Energy Efficiency and Renewable Energy to MEET Florida s Growing Energy Demands, ACEEE Report E072, June Ibid 2

4 Florida faces significant decisions about its energy future. The state is currently making investments in new coal, gas and potentially nuclear generation to ensure the state has enough power to sustain its economic future. If Florida chooses to increase investments in energy efficiency rather than construction of conventional power generation it would result in a savings to the consumer of over $5 billion dollars while stimulating the creation of over 14,000 jobs. 3 Reducing energy use will also reduce greenhouse gas emissions from fossil fuel generation at power plants. Recent studies have outlined how energy efficiency can significantly offset the majority of the projected load growth in Florida over the next fifteen years, decreasing consumer utility bills, stimulating job growth, and creating a more sustainable environment. Improving the energy efficiency in existing buildings is the key to reduce existing energy use. The question is what role do window films play in reducing energy consumption in existing buildings. There are two applications of window film: internal and external. Internal window films are applied to the internal surface of the fenestration. One advantage of internal films is their ease of application, thus reducing the applied cost. Externally applied window films are weatherable films which are applied to the external surface of the fenestration. They have been commonly used on office buildings, but to date less so on homes. External window films reject solar energy before it enters the fenestration product, allowing for better solar control and reducing the potential for window overheating problems that may occur with some films on newer double or triple pane window constructions. Both internal and external window films come in ranges of shades from visually clear to darker shades of grey and bronze, with varying degrees of solar energy reduction. The most common types of window film are: solar control film, safety/security film, and decorative film. Solar control window films can block up to 84% of the solar energy that would normally enter through windows. Window films have additional consumer benefits that include: blocking ultra- violet (UV) rays- a major cause of fading rugs, draperies and artwork; protecting occupants from UV exposure; and, reducing hot spots in homes caused by solar energy entering through windows. The window film industry is represented by the International Window Film Association (IWFA). All IWFA manufacturers have published information available for consumers to match the appropriate window film to the window. All window films offered for solar control by IWFA manufacturers are also third- party certified by the National Fenestration Rating Council (NFRC) for U- Factor, Solar Heat Gain Coefficient (SHGC) and Visible Transmittance (VT). The IWFA is the only window film industry trade association with agreed standards for the measurement and reporting of product performance to consumers. Energy Analysis This study reviews the impact of internal and external window films when applied to a typical existing Florida residence. This study reviewed the energy impacts of window films in four cities to determine 3 Ibid 3

5 energy savings by climate. The energy savings from window films will be compared to other common residential energy efficiency retrofit measures. Description of Existing Home Baselines There are over 9,000,000 dwelling units in Florida. Approximately 58% of these are single family dwellings, 30% are attached dwellings and 12% are mobile homes 4. To determine the typical impact of window film on housing the study used two single family homes to represent the existing Florida housing stock. One home represents the homes built in the 1980s and earlier. The other home represents homes built in the 1990s and later. The 1980s home used for simulation was a 1767 square foot single story, three bedroom house. It was built on a slab with a composition roof and an unvented attic. This home had typical 15% glazing. The 265 square feet of windows were weighted front and back (65 square feet at front, 40 square feet at left, 130 square feet back and 30 square feet at right). This house was assumed to be built with the mechanical efficiencies, insulation levels and other features according to the TABLE A Characteristics of Florida Energy Code Baseline Homes by Vintage published by the Florida Solar Energy Center (FSEC). 5 It was assumed that this home was built to the 1982 Florida Energy Code. The 1990s home used for simulation was a 2000 ft 2, single story, three bedroom house with 15% glazing. The 300 square feet of windows were weighted front and back (74 square feet at front, 49 square feet at left, 139 square feet back and 38 square feet at right). It was built on a slab with a composition roof and an unvented attic. This house was assumed to be built with the mechanical efficiencies, insulation levels and other features according to the TABLE A Characteristics of Florida Energy Code Baseline Homes by Vintage published by the Florida Solar Energy Center (FSEC). 6 It was assumed that this home house was built to the 1991 Florida Energy Code. The baseline window type is clear, single or dual pane glass. The 1980 s baseline window used clear single pane, metal framed windows. The 1990 s home window type used clear dual pane, metal framed windows. The NFRC data for window film is benchmarked against clear glass. The window film U- Factor and SHGC are determined by NFRC certified ratings. Table 1 describes the 1982 and 1991 Florida Energy Code requirements assumed for the climate regions of Florida and used in the modeling runs. 4 U.S. Census Bureau, Census 2012, Table DP- 4 5 Effectiveness of Florida s Residential Energy Code: , FSEC- CR , June 15, Ibid 4

6 Table 1: Florida Energy Code Requirements 7 Northern Northern Central Central Southern Southern Florida Florida Florida Florida Florida Florida Code Year R R R Ceiling R- 19 R- 30 R- 19 R- 30 R- 19 R- 30 Walls R- 11 R- 19 R- 11 R- 19 R- 11 R- 19 Glazing (U/SHGC) 1.30 / / / / / / 0.66 Entry Doors R- 2.0 R- 5.0 R- 2.0 R- 5.0 R- 2.0 R- 5.0 Slab Edge N/A R- 3.5 N/A R- 3.5 N/A N/A Envelope Leakage (ach 50) Heating System (type / Efficiency) Strip Heating / 1 COP Heat Pump / 6.8 HSPF Strip Heating / 1 COP Strip Heating / 1 COP Strip Heating / 1 COP Strip Heating / 1 COP Cooling System (type / Efficiency) Ducting Leaks R- value Location Interior Attic Interior Attic Interior Attic AHU Garage Garage Garage Garage Garage Garage Water Heating (Type / EF) 40 gal; Electric / gal; Electric / gal; Electric / gal; Electric / gal; Electric / gal; Electric / 0.88 Description of Variables The homes were simulated with energy features from the relevant energy code requirements in four Florida locations with city specific weather files. The cities were chosen in order to get a range of climate conditions and representative areas with the greatest number of homes. The cities were Miami, West Palm Beach, Tampa and Jacksonville. These cities are representative of the areas where most homes exist in Florida. Jacksonville, Tampa and West Palm Beach are located in the International Energy Conservation Code (IECC) Climate Zone 2 while Miami is in IECC Climate Zone 1. Both zones are considered hot and humid climates. To get a better understanding of the specific city climates the heating and cooling degree days for these four cities are listed below in Table 2. 7 Ibid, Table A, Characteristics of Florida Energy Code Baseline Homes by Vintage 5

7 Table 2: Heating and Cooling Degree Days Heating Degree Days Cooling Degree Days Miami 20 4,198 West Palm Beach 323 3,891 Tampa 725 3,427 Jacksonville 1,434 2,511 Using data from manufacturers and the NFRC Certified Products Directory, the internal window film products currently in the market were characterized into three groups, good, better and best options with a rounded median value chosen for the SHGC. The good, better, and best categories represent the basic groups of technology films which limit solar heat gain. Good represents standard window films. Better represents spectrally selective window films. Best represent window films with spectrally selective and low- E qualities. The pricing of these films varies based on the product cost. Installation costs are similar for each group of internal films and the prices used reflect the combined cost of both product and installation. The U- Factor and SHGC values and costs per square foot for installed internal window films are detailed in Table 3. The National Fenestration Rating Council (NFRC) uses a 1.09 U- Factor single pane window to test and rate window films. This study chose to use the 1.09 U- Factor for single pane windows to estimate energy savings instead of 1.3 U- Factor as listed in the Florida Energy Code Vintage Tables. The energy estimates from the 1.09 U- Factor single pane windows accurately reflect the U- Factor and SHGC value impacts for window films using the nationally accredited NFRC ratings. Using a 1.30 U- Factor, which may be more representative of thirty year old single pane windows, would produce more potential energy savings. Thus, the energy estimates for this study should be conservative. Table 3: Properties of Windows Studied for the Internal Film Without Good Better Best U- Factor Single Pane Double Pane SHGC Single Pane Double Pane Cost/ft 2 $4.00 $7.00 $9.00 Using data from manufacturers and the NFRC Certified Products Directory, the external window films products currently in the market were also characterized into three groups, good, better and best options with a rounded median value chosen for the SHGC. Installed window film prices include the window film itself, installation supplies needed, and installation labor and setup costs (ladders, scaffolding, etc.) to do the job properly. The SHGC values and costs per square foot of installed external 6

8 window films are detailed in Table 4. Costs used for this study reflected the simplicity of installing external window film on a single story home. Table 4: Properties of Windows Studied for the External Film Without Good Better Best U- Factor Single Pane Double Pane SHGC Single Pane Double Pane Cost/ft 2 $5.00 $5.00 $5.00 $8.50 $8.50 $8.50 $12.00 $12.00 $12.00 Simulation Software The simulation software used for the residential models is EnergyGauge v3.1.00, which is the Florida Department of Community Affairs Energy Code approved software for demonstrating energy code compliance. EnergyGauge is an hourly annual simulation model based on DOE 2.1E software to estimate annual energy use in buildings. Residential simulations were run in the worst case orientation as determined by worst case function in the EnergyGauge software. Methodology For residential applications it is critical to determine which energy efficiency measure is the most cost effective when compared to other typical energy retrofit items. This allows the homeowner or state policy maker a comparison of the effectiveness of energy efficiency measures that may be used to improve the efficiency of an existing home. The EnergyGauge software calculates energy savings in site kilowatt per hour (kwh) which represents the electric energy use as reported to the consumer in their utility bill. The kwh energy is not only related to the utility bill but also is related to peak load. Florida has a significant summer peak load due to air conditioning and an additional winter peak load due to electric heating from older heat pumps with electric resistant heat strips. Window film was compared to typical retrofit options for improving the energy efficiency of an existing home. These options are increasing the ceiling insulation, replacing the Heating, Ventilation, and Air Conditioning (HVAC) system (air conditioner and/or heat pump), and sealing the building envelope to reduce infiltration. The energy efficiency features that internal and external window films were compared to for existing homes are: R- 38 ceiling insulation adding insulation to the attic 13 SEER replacing air conditioning equipment with more efficient new unit 7.7 HSPF replacing heating equipment with a more efficient new unit (heat pump) 7

9 Air Sealing sealing gaps in building envelope (walls, doors, around windows, etc.) Each energy feature s reduction in electricity use (kwh) was determined through EnergyGauge simulations. The cost of each improvement was estimated from existing cost databases. Each energy feature was then ranked by their reduction in energy use (kwh) divided by their cost. Results Figures 2 through 5 illustrate relative savings per dollar spent for the internal and external window films (good, better and best) at their specific price points, and the typical retrofit features (ceiling insulation, replacing mechanical equipment and air sealing). The charts values were determined by calculating the energy savings predicted by EnergyGauge divided by the installed cost. The red bars represent the effect of window film on existing double pane glass. The blue bars represent the other typical retrofit energy efficiency measures. The charts are presented in a north to south order. To simplify the charts only the results for three internal films and the $8.50 per square foot external film were compared to typical retrofit features. The following charts do not represent any impact on peak load. Since window films reduce the majority of solar heat gain (up to 84 %) through windows there will be a significant reduction in summer peak load. The impact on peak load is especially significant due to the reduced need for less efficient (more polluting) fossil fuel peaker power plants to generate power during critical peak loads. Any reduction in summer peak loads will reduce carbon emissions as well as the consumer s utility bill. ResidenVal Retrofits - Window Film Savings per Cost for Energy Measures Miami External Best Film ($8.50) Internal Best Film External Bener Film ($8.50) Internal Good Film External Good Film ($8.50) Internal Bener Film 13 SEER Ceiling Insulamon (R- 38) Air Sealing (3.0 SLA) 7.7 HSPF RelaVve Energy Savings per Dollar Spent Figure 2: Residential Retrofits Window Film, Savings per Cost for Energy Measures Miami 8

10 ResidenVal Retrofits - Window Film Savings per Cost for Energy Measures West Palm Beach External Best Film ($8.50) Internal Best Film External Bener Film ($8.50) Internal Good Film Internal Bener Film External Good Film ($8.50) 13 SEER Ceiling Insulamon (R- 38) Air Sealing (3.0 SLA) 7.7 HSPF RelaVve Energy Savings per Dollar Spent Figure 3: Residential Retrofits Window Film, Savings per Cost for Energy Measures West Palm Beach ResidenVal Retrofits - Window Film Savings per Cost for Energy Measures Tampa External Best Film ($8.50) Internal Best Film External Bener Film ($8.50) Internal Good Film Internal Bener Film External Good Film ($8.50) 13 SEER Ceiling Insulamon (R- 38) 7.7 HSPF Air Sealing (3.0 SLA) RelaVve Energy Savings per Dollar Spent Figure 4: Residential Retrofits Window Film, Savings per Cost for Energy Measures Tampa 9

11 ResidenVal Retrofits - Window Film Savings per Cost for Energy Measures Jacksonville External Best Film ($8.50) Internal Good Film Internal Best Film External Bener Film ($8.50) Internal Bener Film External Good Film ($8.50) 13 SEER Ceiling Insulamon (R- 38) Air Sealing (3.0 SLA) 7.7 HSPF RelaVve Energy Savings per Dollar Spent Figure 5: Residential Retrofits Window Film, Savings per Cost for Energy Measures Jacksonville The results consistently show internal and external window films save more energy per dollar spent than typical retrofit features. From a state energy policy perspective internal and external window films are more effective than ceiling insulation, replacing mechanical equipment and air sealing in all four Florida cities analyzed. The effectiveness of window films increase as the cooling degree days increase (i.e.; the further south in Florida the more cost effective window films become). Window films reduce energy (kwh) two to four times more cost effectively than installing R- 38 ceiling insulation over the existing R- 30 ceiling insulation. Window films are eight to fifteen times more cost effective than reducing the air infiltration of homes. Window films are three times more cost effective than replacing the air conditioner. Replacing the heat pump for heating was determined not to be a good retrofit item since there are minimal heating loads in three of the four cities studied. Recall that these results are using a 1.09 U- Factor single pane window for the base case house. Florida s Energy Code Vintage Table recommends using a 1.3 U- Factor single pane window for existing residential homes. Thus, the single pane results are conservative and energy savings per dollar spent should be higher. Determination of Payback To determine typical paybacks for home owners the energy savings for typical 1980s home (labeled single pane below) and a typical 1990s home (labeled dual pane below) was determined. Electricity costs used to determine the annual energy savings are the average retail price of electricity for Florida in 2013 as published by the Electric Institute of America. The cost was cents per kwh. As Florida 10

12 moves toward time- of- use (TOU) or dynamic pricing rates the higher TOU rate of cents per kwh was used to determine the energy savings during peak load from window film. This higher cost of electricity (kwh) was used in the dynamic price response pilot funded by the Florida Public Utility Commission in This pilot is being used to determine the impact of TOU price signals on homeowner s behavior. As utilities align their electricity charges with their power costs TOU rates will become more prevalent. Florida Power and Light (FPL) currently offer residential and commercial TOU rates on their manage my account portion of the FPL webpage 9. The installed cost per square foot used for internal film is from Table 3. To simplify the following external film tables the installed cost per square foot for external film was $5.00 for good film, $8.50 for better film and $12.00 for best film. At peak load pricing the internal window films have a payback between 2.5 to 7.4 years for single pane windows and 5.2 to 11.7 years on dual pane windows. Typical internal window film paybacks were 4.1 years for single pane and 6.9 years for dual pane windows. The good window film had the shortest payback on single pane windows and best for dual pane windows. The payback period decreased with an increased cooling load. Miami had a 2.5 year payback on single pane windows and a 5.3 year payback on dual pane windows. At peak load pricing the external window films have a payback between 3.5 and 8.3 for single pane windows and 4.2 to 9.9 years on dual pane windows. Typical external window film paybacks were 4.7 years for single pane and 6.0 years for dual pane windows. The good window film had the shortest payback on single and dual pane windows. Once again, Miami with the largest cooling load had the shortest external window film payback periods (3.5 years for single pane; 4.2 years for dual pane). From a Florida consumer perspective, window films are good investments to reduce their utilities costs. Installing window film as a retrofit measure on a typical home yields a payback period between three to seven years depending on the homeowner s cost of power (see Tables 5 and 6). As Florida utilities move towards TOU rates the payback for the good, better and best window films was close to four years. Once again, these energy savings calculated to determine payback used a 1.09 U- Factor single pane window for the base case house. Florida s Energy Code Vintage Table recommends using a 1.3 U- Factor single pane window for existing residential homes. Thus, the single pane results are conservative and actual energy savings per dollar spent should be higher. 8 Florida Public Service Commission, Docket No EG; Order No. PSC TRF- EG; Issued: June 13, 2011, page

13 Table 5: Simple Payback for Internal Window Film Internal Window Film Payback Single Pane Dual Pane Miami Good Better Best Good Better Best Film Cost $1,060 $1,855 $2,385 $1,204 $2,107 $2,709 Annual Energy Savings (kwh) 1,669 2,242 3, ,125 2,227 Annual Energy Cost Savings $189 $254 $345 $100 $127 $252 Simple Payback (Years) Peak Load Energy Cost Savings $431 $579 $788 $229 $291 $575 Simple Payback (Years) Tampa Good Better Best Good Better Best Film Cost $1,060 $1,855 $2,385 $1,204 $2,107 $2,709 Annual Energy Savings (kwh) 1,365 1,885 2, ,002 1,882 Annual Energy Cost Savings $155 $213 $292 $92 $113 $213 Simple Payback (Years) Peak Load Energy Cost Savings $353 $487 $667 $209 $259 $486 Simple Payback (Years) West Palm Beach Good Better Best Good Better Best Film Cost $1,060 $1,855 $2,385 $1,204 $2,107 $2,385 Annual Energy Savings (kwh) 1,634 2,151 2, ,100 2,105 Annual Energy Cost Savings $185 $243 $331 $101 $125 $238 Simple Payback (Years) Peak Load Energy Cost Savings $422 $556 $755 $231 $284 $544 Simple Payback (Years) Jacksonville Good Better Best Good Better Best Film Cost $1,060 $1,855 $2,385 $1,204 $2,107 $2,385 Annual Energy Savings (kwh) , ,203 Annual Energy Cost Savings $68 $110 $161 $64 $79 $136 Simple Payback (Years) Peak Load Energy Cost Savings $156 $252 $366 $145 $180 $311 Simple Payback (Years)

14 Table 6: Simple Payback for External Window Film External Window Film Payback Single Pane Dual Pane Miami Good Better Best Good Better Best Film Cost $1,325 $2,253 $3,180 $1,505 $2,559 $3,612 Annual Energy Savings (kwh) 1,472 2,266 3,106 1,374 2,038 2,772 Annual Energy Cost Savings $167 $257 $352 $156 $231 $314 Simple Payback (Years) Peak Load Energy Cost Savings $380 $586 $803 $355 $527 $716 Simple Payback (Years) Tampa Good Better Best Good Better Best Film Cost $1,325 $2,253 $3,180 $1,505 $2,559 $3,612 Annual Energy Savings (kwh) 1,209 1,795 2,392 1,193 1,749 2,212 Annual Energy Cost Savings $137 $203 $271 $135 $198 $250 Simple Payback (Years) Peak Load Energy Cost Savings $312 $464 $618 $308 $452 $572 Simple Payback (Years) West Palm Beach Good Better Best Good Better Best Film Cost $1,325 $2,253 $3,180 $1,505 $2,559 $3,612 Annual Energy Savings (kwh) 1,454 2,158 2,940 1,305 1,928 2,614 Annual Energy Cost Savings $165 $244 $333 $148 $218 $296 Simple Payback (Years) Peak Load Energy Cost Savings $376 $558 $760 $337 $498 $675 Simple Payback (Years) Jacksonville Good Better Best Good Better Best Film Cost $1,325 $2,253 $3,180 $1,505 $2,559 $3,612 Annual Energy Savings (kwh) 1,195 1,369 1, ,134 1,417 Annual Energy Cost Savings $135 $155 $168 $94 $128 $160 Simple Payback (Years) Peak Load Energy Cost Savings $309 $354 $384 $214 $293 $366 Simple Payback (Years)

15 Conclusions Window film applied to existing housing is one of, if not the most, cost effective energy efficiency improvements a homeowner can make to Florida housing. Window films are more cost effective than installing new mechanical equipment, adding ceiling insulation or improving air sealing in all four Florida cities analyzed. The effectiveness of window films increases as the cooling degree days increase. Window films reduce energy (kwh) two to four times more cost effectively than installing R- 38 ceiling insulation over the existing R- 30 ceiling insulation. Window films are eight to fifteen times more cost effective than reducing the air infiltration of homes. Window films are three times more cost effective than replacing the air conditioner. Window film payback periods can be less than four years when peak pricing is used. Window films will reduce summer peak load. Window films should be considered as one of the most effective options to achieve the state of Florida s goal of reducing energy consumption by 29% through energy efficient retrofits. Window films should be promulgated in energy conservation, peak demand reduction efforts and utility incentive programs in the state of Florida. 14