Bergmeyer
Bergmeyer
Where Design Meets Performance An Energy Use Analysis of Big Box Retail Stores
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Where Design Meets Performance
Bergmeyer
Bergmeyer 51 Sleeper Street Boston, MA 02210 617.542.1025 www.bergmeyer.com
Bergmeyer
Goals and Process
As a signatory to the 2030 Challenge and the AIA 2030 Commitment, Bergmeyer is always seeking ways to reduce the energy consumption and carbon footprint of our projects. We believed there were opportunities to reduce the energy consumption of a client’s big box stores to save on operating costs. From its early days as a homebased business more than 50 years ago, the company had grown into a national retailer with a portfolio of 65 stores. With another 19 locations in the works, their real estate represents millions of square feet of floor space. We initiated an analysis of a 96,000 sf prototype design store and an operational store to determine what cost-effective energy efficiency improvements could be made. This report summarizes the
results of the energy modeling process and outlines the recommended energy conservation measures (ECMs) for the prototype design. The building components analyzed for efficiency upgrades were selected based on their energy-use implications, their expected payback, and compliance with the 2012 International Energy Conservation Code. (The 2012 International Energy Conservation Code (IECC) is the current version of the model energy building code. As of February 2015, it has been adopted in 15 states and the District of Columbia.) We constructed an energy model with our partners at TLC Engineering for Architecture using the prototypical design
documents. The model was then calibrated using the actual energy use data from a store located in the Midwest region. The store operates 13 hours a day, 6 days a week, and 10 hours on Sundays, 362 days a year. The model allowed us to create a benchmark against which we could evaluate design options that would increase energy efficiency and result in a high-performance prototype for future stores.
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Where Design Meets Performance
Energy Usage PROTOTYPE DESIGN ENERGY USE FINDINGS Lighting and heating alone account for more than 50% of the energy use in the prototype store. With fan energy included, the total is more than 75% for those three uses.
MISC. 9%
PLUG LOADS 7%
LIGHTING 27%
COOLING 9%
FAN ENERGY 23%
HEATING 25%
HVAC (heating, cooling, and fan energy) accounts for 57% of energy use. While lighting, heating, and fans use about the same amount of energy, heating cost would be the lowest of the three since gas is cheaper than electricity. The suggested energy efficiency improvements focus on the largest energy users. LIGHTING Calculated payback helped identify the optimal upgrades. COMPARISON OF ENERGY USE IN PROTOTYPE DESIGN STORE AND MIDWEST STORE Using actual data from the Midwest store in the energy model allowed us to see how the actual energy use compared to the predicted energy use. The predicted and actual energy use are fairly in line with a maximum variation of 4%, with the exception of heating. This is most likely due to the fact that we did not have a full season of heating bills for review. This model also created a benchmark against which suggested improvements could be measured, allowed us to develop energy efficiency recommendations, and helped identify cost savings opportunities.
27%
Prototype
31%
Midwest Store HEATING 25%
Prototype 16%
Midwest Store FAN ENERGY
23%
Prototype
25%
Midwest Store COOLING 9%
Prototype
10%
Midwest Store PLUG LOADS Prototype Midwest Store
7% 7%
MISCELLANEOUS Prototype Midwest Store
9% 11%
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Findings and Recommendations KEY FINDINGS An optimal upgrade package of energy conservation measures was developed for the prototype design. It predicted a savings of approximately $40,000 a year per store, with a 17.7% ROI and a 5.6year simple payback.
1 LOCATION $40,000 ANNUAL SAVINGS
If the upgrade package were implemented at the 19 planned locations, the cost savings could run up to $760,000 a year. The current expected ENERGY STAR score for the Midwest store is 64. If all recommended measures were implemented, the new projected score would be 75, which would qualify the store as an ENERGY STAR certified building.* RECOMMENDED ENERGY CONSERVATION MEASURES (ECM) • Lighting System Upgrade • Cooling and Heating System Upgrade • Additional Skylights • Increased Insulation • Renewable Energy Six different HVAC options were modeled to determine low-, medium-, and highimpact packages for improving the energy efficiency of the prototype. All three packages include the ECMs required to make the prototype design compliant with the 2012 International Energy Conservation Code (IECC). The medium-impact package was determined to be the best option for the Midwest climate zone. When the recommended ECMs are bundled together as part of a energy efficiency strategy, they offer an attractive payback and rate of return over the life of the investment. Implemented individually, the ECMs do not offer the same results. * An ENERGY STAR of 50 is the median. An ENERGY STAR score of 64 means that it performs better than at least 64% of similar buildings nationwide.
19 LOCATIONS $760,000 ANNUAL SAVINGS
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Lighting System Upgrade Lighting is the largest and the most expensive energy use as it runs on electricity. While lighting quality is one of the most important factors in the store’s design, there are opportunities to reduce the overall lighting power without sacrificing lighting quality or merchandise presentation.
PROPOSED FIXTURES
Ratio Canopy 4.0 TLROC40
I-BEAM LED
The largest quantity of current fixtures are high-bay fixtures which utilize four 42-watt CFLs and direct approximately 15% of their light upward and only 85% downward toward the merchandise. The currently specified fixtures are reasonably efficient with a design lighting power density of 1.32 W/sf, however there are opportunities to save energy by utilizing LED fixtures and/or revising the lighting layout. Lighting power density reductions were modeled to show approximate energy and dollars saved annually: PROPOSED FIXTURES By utilizing an equivalent LED fixture such as the Hubbell Acrylic LED Highbay, which directs 100% of its lighting power downward, lighting power could be reduced by approximately 45%, and the required lighting levels, color temperature and CRI would still be maintained. While the I-BEAM LED fixture has a lower cost premium and a shorter payback, the Hubbell fixture offers the greatest LPD reduction and energy savings, and the payback period is only 8 months longer. These fixtures also have longer life spans, which means reduced lifetime maintenance costs.
Hubbel Acrylic LED High-Bay
LPD REDUCTION 33% 35% 45% ENERGY SAVED 247,437 kWh 261,631 kWh 328,378 kWh ENERGY COST SAVINGS $23,000 $24,000 $31,000 FIRST COST PREMIUM $250,000 $25,000 $56,000 PAYBACK IN YEARS 10.7 years 1 year 1.8 years
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Heating and Cooling System Upgrade The HVAC system comprises 57% of the energy use, providing significant opportunity to reduce energy costs through equipment upgrades. Investing in an efficient HVAC system will produce a payback in less than 9 years. The most efficient HVAC system for the Midwest climate zone was found to be:
• Direct Expansion (DX) dedicated outside air system with energy recovery • Packaged DX VAV with hot water reheat • Condensing boiler for hot water reheat
Additional Skylights One of the major changes from the 2009 to the 2012 IECC is the requirement that at least half of the floor area must be in a daylighting zone under skylights in certain building types over 10,000 square feet with ceilings more than 15 feet high, retail included. These requirements are waived in climate zones 6 through 8. As a part of our analysis for climate zones 1 through 5, we wanted to think proactively and design towards the future. As a result, we added forty 5’-0” x 5’-0” skylights to the prototypical design. Operated in conjunction with daylighting controls, the skylights would reduce lighting demand, lower electricity costs, increase both occupant comfort and experience within the store and provide increased sales. While the skylights contribute to overall energy improvements, in isolation, they offer no payback as the reduced lighting demand is offset by increased heat loss.
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Increased Insulation
Renewable Energy
While not factored into the energy cost savings, a tight building envelope with the appropriate amount of insulation is one of the most important components of energy efficiency.
The store has a large amount of roof space available for photovoltaic arrays.
Our analysis found that increasing the R-value of the roof and wall insulation didn’t offer a payback but might be a worthwhile investment as energy codes become more stringent. We recommended improving the insulation by increasing the wall assembly R-value from 12 to 15 and increasing the roof insulation R-value from 20 to 25. • •
INCREASE WALL ASSEMBLY R-VALUE FROM R-12 TO R-15 INCREASE ROOF INSULATION R-VALUE FROM R-20 TO R-25
Credits: cthomeinsulation.com, wdgsilicones.com
A PV array capable of producing at least 5% of the annual energy use would be approximately 136 kW, occupying about 13,600 square feet of roof space, with an installed cost of approximately $408,000. Up to 60% of the cost of a solar installation could possibly be offset with incentives and rebates. In addition to purchasing PV systems, there are options for leasing systems and for leasing roof space to outside parties under a solar power purchasing agreement.
Credit: Flickr h080
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Payback Analysis of Energy Conservation Measures LIGHTING SYSTEM UPGRADE LIGHTING SYSTEM OPTION 1 Ratio Fixture, 33% LPD Reduction Cost Premium $249,000 Annual Savings $23,179 Payback 10.7 years payback LIGHTING SYSTEM OPTION 2 LED Highbay, 45% LPD Reduction Cost Premium $56,440 Annual Savings $31,043 Payback 1.8 years payback
Payback Cost Premium
INCREASE TO R-25 ROOF Cost Premium $0 Annual Savings $199 Payback Nonquantifiable INCREASE TO R-15 WALL (R-11.6 EFFECTIVE) Cost Premium $0 Annual Savings $205 Payback Nonquantifiable
ADDITIONAL SKYLIGHTS Skylights with daylight harvesting Cost Premium $55,000 Annual Savings None Payback None
LIGHTING SYSTEM OPTION 3 IBL Fixture, 35% LPD Reduction Cost Premium $24,900 Annual Savings $24,530 Payback 1.0 year payback
Lighting System Option 2
$100,000
INCREASED INSULATION
HEATING & COOLING SYSTEM UPGRADE DX dedicated outdoor air system packaged dx vav w/ hot water reheat condensing boiler for hot water reheat Cost Premium $166,300 Annual Savings $18,885 Payback 8.8 years payback
Lighting System Option 3
Heating & Cooling Upgrade
Lighting System Option 1
$50,000
Increased Insultation
$0
$50,000 Additional Skylights
$100,000
$150,000
$200,000
$250,000 0 1 Years
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Conclusion
In this report we have outlined energy conservation measures designed to help our client’s prototype store operate more efficiently. They include: • Improving the building envelope • Incorporating additional skylights and daylight harvesting • Reducing the lighting power demand with the introduction of natural light and more efficient fixtures • Investing in an advanced heating and cooling system • Installing a rooftop solar array
With a few relatively simple changes to the prototype design, each store could see a savings of as much as $40,000 per year, and the upgrades could pay for themselves in 5.6 years. The initial investment of $221,000 per store would be expected to have a 17.7% return on investment (ROI). While a per store savings of $40,000 a year may seem modest, this translates into significant savings when multiplied across a portfolio of 19 planned stores.
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ABOUT US Bergmeyer is design firm committed to enhancing people’s everyday lives — we create experiential environments while achieving successful measurable results. Our commitment to sustainable design and environmental stewardship drives the firm’s efforts to incorporate environmental responsibility, high-performance design, building systems integration, and sustainable strategies into all of our projects and internal operations. Bergmeyer staff is available to present on our experiences and on a wide range of sustainability and LEED topics. If interested, contact Dee Spiro, Director of Sustainability at Bergmeyer. CONTACT US
k Dee Spiro, dspiro@bergmeyer.com
Bergmeyer 51 Sleeper Street Boston, MA 02210 617.542.1025 www.bergmeyer.com
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Where Design Meets Performance
Bergmeyer
Bergmeyer 51 Sleeper Street Boston, MA 02210 617.542.1025 www.bergmeyer.com