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Incorporate high-performance energy efficiency measures into your new retail development. You can reduce energy costs for years to come and qualify for incentives that will offset the cost of your improvements!
The technical guides below explain how and why you should incorporate energy efficiency strategies into your next retail project.
It's about more than choosing LED light fixtures, which provide higher-quality illumination and use less energy than other types of lighting. Reduce lighting power without sacrificing functionality by decreasing total installed wattage through thoughtful design and consideration of necessary light levels.
High-efficiency LED lights have longer lifespans and can significantly reduce or even eliminate maintenance costs. No additional cost is required for disposal of hazardous materials, as is needed with fluorescents.
For a target level of 0.77 W/sf, annual energy savings range from 8% to 10%, depending on the building's operating schedule.
By using LED fixtures and light levels consistent with Illuminating Engineering Society of North America (IESNA) recommendations, a best-practice interior lighting power density may cost less than meeting the baseline with fluorescent fixtures, meaning payback is immediate.
LED lighting offers better glare control and uniformity than alternative lighting options.
Improved lighting quality is linked to improved employee morale, leading to increased productivity and fewer lost staff hours.
Lower installed lighting power density means LEDs produce less heat, resulting in an ancillary benefit of reduced summer cooling costs.
Specify use of LED fixtures with a target LPD of 0.77 W/sf or less.
Design light levels consistent with IESNA recommendations.
Many retail applications have lighting power density values as low as 0.50 W/sf with current technology.
Select fixtures that meet DesignLights Consortium® Qualified Projects List (DLC QPL) premium performance requirements:
As with interior lighting, exterior lighting efficiency is about more than simply choosing LEDs. Strategic design addresses any security concerns while not exceeding recommended light levels. Designers should incorporate high-efficacy fixtures from the array of LED products on the market.
High-efficiency LED lights have longer lifespans and can significantly reduce maintenance costs. Additionally, instant on/off control reduces the need for supplemental life safety lighting components.
Buildings that implement best-practice efficient exterior lighting can expect to save 2% to 4% of building energy costs, with payback in one year or less.
LED lighting offers better glare control and uniformity than alternatives, contributing to improved facial and object identification. Customer satisfaction and comfort can be achieved with lower installed lighting power designs while reducing light pollution and light trespass. Safety and security concerns can be met without exceeding desired light levels. The dimmability of LED light fixtures allows for rightsizing light levels post-installation.
Do not exceed Illuminating Engineering Society of North America's (IESNA) recommended light levels (0.2 to 0.5 foot-candles for parking lots) for the building's exterior lighting zone. Confirm any specific security issues requiring enhanced lighting.
Target selection of DLC QPL premium performance requirements:
Even the most efficient lighting designs can benefit good lighting control strategies. Dim building-mounted and pole-mounted fixtures during nighttime hours while turning off landscape and accent lighting.
Thoughtful lighting zoning control and sequencing reduces energy use and increases lighting lifespan without affecting functionality.
Lighting controls are required by the energy code, so implementing a more aggressive control strategy does not add to the first cost of a project.
Implementing best-practice exterior lighting controls results in electric energy savings of 1% to 2%, with payback in a year or less due to low first cost.
Simply increasing light levels does not necessarily enhance safety or security. A U.S. Department of Energy report (PNNL-18173) suggests that high-quality exterior lighting design contributes to safety and security.
Effective control of exterior lights can also reduce light pollution and light trespass.
Group exterior lights into at least three zones:
When operating hours are known, implement schedule-based controls to turn off, or significantly reduce, essential dusk-to-dawn fixtures in unoccupied areas of the parking lot.
When operating hours are unknown, consider motion controls to turn off, or significantly reduce, lighting.
More granular zoning of large exterior parking areas increases savings, as sensors only activate some portion of the exterior area lighting.
As with all control measures, post-occupancy commissioning and verification is important to ensure lighting operates as designed. Consider sensor calibration and adjusting time delays.
Retail buildings often use rooftop units (RTUs) for cooling and ventilation. RTU air conditioning efficiency is measured as an Integrated Energy Efficiency Ratio (IEER). RTUs with higher IEERs use less energy to cool a space.
Consortium for Energy Efficiency (CEE) publishes tiers of efficiency ratings to help design professionals specify efficiencies.
Some buildings use chiller equipment to cool water. For this equipment, specify an Integrated Part Load Value (IPLV) 10% better than the code minimum.
Higher efficiency RTUs are a low-cost, energy-saving upgrade. Units cost $19 to $65 more per ton of cooling, with a typical incremental cost of less than $0.30/gsf.
Cooling electricity cost is cut by 10% or more in a typical application, resulting in a simple payback of less than seven years.
High-efficiency RTUs add value to a building, which can increase sale price and lease rates.
There are two efficiency ratings for RTU air conditioners:
The most efficient RTUs and chilling equipment have variable speed compressors and fans with integrated controls. These systems can match the exact cooling load required, saving more energy than staged compressors that tend to overcool the air at part-load conditions.
Specify or schedule a rooftop unit that meets the Consortium for Energy Efficiency (CEE) High Efficiency Commercial Air Conditioning and Heat Pump Initiative Tier 1 Minimum IEER. For even better performance, specify rooftop units at CEE Tier 2, CEE Advanced Tier, or even higher IEER.
For chilled water equipment, specify chiller equipment with a minimum Integrated Part Load Value (IPLV) that is 10% or higher than code minimum.
Occupancy of a retail building varies significantly throughout the day. Demand-Controlled Ventilation, or DVC, can reduce outside air intake when the sales floor is less occupied.
Simple DCV consisting of CO2 sensors in the retail space cost less than $2,000 per air-handling unit. Alternatively, if occupancy sensors for lighting are installed, these can be integrated to provide control for DCV in lieu of CO2 sensors.
Implementing DCV can save $30 per 1,000 square feet of air-conditioned retail floor, with a simple payback of seven years.
DCV can add as much as $0.04/gsf net present value to your property.
Use CO2 sensors to track retail floor occupancy. Providing adequate ventilation improves indoor air quality and makes the space feel fresh for customers. Alternatively, occupancy sensors may deliver comparable quality and effectiveness.
A certain amount of ventilation air is always necessary to offset exhaust in the back-of-house areas for trash rooms and other pollutants.
Check with your local authority having jurisdiction to ensure the building meets local ventilation code requirements.
One simple DCV control system has a CO2 sensor in the zone’s breathing space or rooftop unit (RTU) return plenum. As occupants breathe and increase the CO2 concentration in the space, the DCV controls open outside air dampers and increase the flow of fresh air into the space.
ASHRAE 62.1-2016 2.6.7.2 allows breathing zone outdoor airflow to be reduced to zero for zones in occupied standby mode.
Refer to ASHRAE Guideline 36-2018 High Performance Sequences of Operation for HVAC Systems for outside air control of single-zone variable air volume air-handling units.
Approximately two inches of insulation is required by code for mass wall types, but adding another inch or more of insulation may make financial sense for a building. It can reduce heating and cooling equipment size and energy costs while also improving occupant comfort. Designers should calculate assembly U-values, not just clear-span U-values, and minimize or eliminate wall penetrations and other thermal bridges.
One-inch-thickness extruded polystyrene (XPS) insulation has an incremental cost of $0.33/ft2. While payback for this measure is three to five years, the lifetime of the wall system is typically equal to the life of the building itself, often 50 years. Gas savings for the building is typically 8% per year, and electricity savings is just under 1% per year.
There are three primary types of continuous insulation used in precast wall systems — extruded polystyrene (XPS), expanded polystyrene (EPS), and polyisocyanurate (polyiso). In most cases, XPS or EPS work well in commercial applications as continuous insulation. Batt insulation, or spray foam, may be used in stud cavities of masonry or steel-framed wall systems, but those applications require careful consideration of moisture transport.
XPS is typically R-5 per inch and maintains its R-value in cold temperatures. Over time, the R-value will slightly decrease. XPS also has vapor and air-barrier properties. EPS is typically R-4 per inch. It is less dense which requires increased thickness compared to XPS. It’s slightly more permeable than XPS. EPS is less expensive than XPS. Polyiso is typically R-6 per inch, however, in cold temperatures, its R-value slightly decreases.
Designers should use caution when designing wall assemblies, avoiding penetrations though the continuous insulation. This is common around loadbearing areas that support the roof deck, as well as window and door openings.
An assembly U-value calculation should be done to ensure the opaque wall assembly achieves 0.06 Btu/hr- ft2-F. If there are significant penetrations through the layer of continuous insulation, increasing the thickness of the continuous insulation layer may be required to achieve 0.06 Btu/hr- ft2-F.
When specifying continuous insulation, state the required thickness for each type of insulation allowed to achieve the desired minimum-aged R-value.
Many retail buildings use gas-fired heating in rooftop units (RTUs) and in make-up air units (MAUs) for heating and ventilation. RTUs are often used for the sales floor, while MAUs are used for back-of-house areas. RTU efficiency can be improved with a condensing furnace. MAU efficiency can be improved by specifying a direct-fired make-up air unit (DFMAU). A DFMAU ignites the gas flame directly in the airstream, avoiding heat exchange loss and resulting in higher efficiency levels.
DFMAUs are a low-cost energy efficiency upgrade. Direct-fired units may cost 10% to 20% more than an indirect unit, with a typical incremental cost of less than $0.50/gsf.
Heating fuel cost is reduced by 10% or more in a typical application when using DFMAUs, resulting in a simple payback of less than five years.
Condensing RTUs can cost about $5 per MBH more than regular RTUs. A typical payback period for condensing RTUs is 10 years.
Some designers may be wary of DFMAUs since combustion byproducts are introduced into the airstream, but byproducts from DFMAUs are typically far below hazardous level thresholds set by OSHA and ANSI. These pollutant concentrations are even less in warehouse applications than other building types, as the high volume of make-up air dilutes the combustion byproducts in the airstream.
The simple design of direct-fired units offers additional benefits of reduced unit size, unit weight and maintenance cost.
Specify direct-fired make-up-air heating and ventilation units with a minimum gas heating efficiency of 92%. Consider referencing the following standards in project requirements:
Specify rooftop units (RTUs) with a condensing furnace having minimum gas heating efficiency of at least 92% per Section 2.39, Thermal Efficiency, ANSI Z21.47. Condensing heating equipment has a maximum efficiency of around 96%.
Lastly, consider recovering heat if there are large amounts of exhaust or if there is a remote refrigeration system. This heat being rejected from the building can instead be used to heat the building in the winter.
Convenience store and supermarket refrigerated cases consume significant amounts of energy. It is relatively simple to reduce energy consumption by selecting efficient cases.
Case manufacturers offer a wide variety of options for refrigerated cases. Opportunities to reduce case energy consumption include: high efficiency LED lighting, electronically commutated fan motors, no-heat doors (in lieu of anti-sweat heaters), and hot-gas defrost for freezer cases (in lieu of electric defrost). In addition, it's highly recommended to use case doors on all cases in the store. Efficient refrigerated cases have a payback of three to five years and can add a net present value to a project of over $2.50/gsf.
High-quality efficient refrigerated cases, particularly those with case doors, create a better shopping experience by making the store more temperate.
Other benefits of efficient cases include:
Specify cases that use 25% less electricity than the daily allowance specified by the Department of Energy. Designers can work with refrigerated case manufacturers to determine which case options should be specified to achieve this performance target.
Deciding whether to include roof-mounted solar photovoltaics (PV) in a new building design can be complicated and require input from multiple stakeholders. However, a few simple choices during design can ensure the building is solar-ready and can reduce later solar-related construction costs by up to 60%.
Solar PV systems perform best when shading from vegetation and neighboring structures is minimized. Site buildings in the least-shaded portion of a lot, designating shady areas for parking and driveways.
Rooftop solar systems weigh from three to six pounds per square foot, so a solar-ready roof must be able to support this.
Minimizing the amount of rooftop equipment and placing all such equipment in a centralized area on the north side of the roof will maximize space and minimize shading for a future solar system.
To accommodate PV, the electrical system must have conduits routed from the roof to the main electric panel. Space should be left near the panel for equipment such as inverters, controllers and switches.
In all as-built drawings and submittals, be sure to record details about design choices made with solar in mind. Consider including details on the code sheet.
If the approximate size and location of a building is known, ComEd's solar calculator can be used to estimate system power and energy production.
On the site plan, indicate the portion of the roof designed to accommodate future PV panels. Provide sufficient roof structure to support this load.
Size the electrical room to accommodate future solar PV equipment.
Visit ComEd.com/Solar to determine if solar is right for you.
