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Incorporate high-performance energy efficiency measures into your new warehouse 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 warehouse project.
It's about more than choosing LEDs. Yes, LED light fixtures 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 0.28 W/sf, annual energy savings range from 5% to 10% of building energy costs, 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 code baseline with fluorescent fixtures. That means 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, which can result in an ancillary benefit of reduced cooling costs in summer.
Achieve lighting power density of 0.28 W/sf or less, including lighting power density values as low as 0.15 W/sf in open-plan warehouses with current technology.
Design light levels consistent with IESNA recommendations.
Select fixtures that meet DesignLights Consortium® Qualified Projects List (DLC QPL) premium performance requirements:
A thoughtful lighting control scheme reduces energy use and increases lighting lifespan without affecting the comfort or productivity of building occupants.
Lighting controls are required by code, so implementing a more aggressive control strategy adds little to no first cost. Since hours of operation are typically long with sparse occupancy, energy savings can be significant with integral light fixture sensors.
Assuming a design lighting power density value of 0.28 W/sf and targeting full shut-off controls within 20 minutes, annual savings are 1% to 3% of building energy costs.
Due to the low first cost, interior lighting controls typically pay back within the first year.
In contrast to fluorescent lights (which have a reduced lifespan with frequent switching), LED lights are not adversely affected by frequent on/off cycling, and in fact last longer with a more aggressive controls strategy due to reduced run-hours.
Occupancy-based controls for warehouses are now required by code. New products that integrate controls into light fixtures make installation and commissioning easier. When properly zoned and commissioned, controls are responsive to occupants and address safety concerns.
Specify lighting with integral motion sensors. Implement automatic shut-off within five minutes of vacancy on a per-fixture sensing basis. With controls implemented on a per-fixture basis, warehouse areas remain illuminated only where physically occupied.
Alternately, implement multi-level or stepped shutoff control of light output, such as 50% reduction in five minutes of vacancy, followed by full shut-off in 20 minutes of vacancy.
Consider networked lighting controls, which allow for advanced control functionality such as task tuning and easy sensor adjustment.
As with all control measures, post-occupancy commissioning and verification are important to ensure lighting operates as designed. Consider sensor calibration and a time delay adjustment.
As with interior lighting, exterior lighting efficiency is about more than just choosing LEDs. Thoughtful design addresses any security concerns strategically 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 from 2% to 4% of their building energy costs, with payback in a 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 trespass. Safety and security concerns can be met without exceeding desired light levels.
Compare your project's Watts per square-foot of parking and drive area and Watts per linear foot of doors to the recommended targets in this guide.
Do not exceed Illuminating Engineering Society of North America's (IESNA) recommended light levels for the building's exterior lighting zone.
Confirm any specific security issues requiring enhanced lighting.
Target selection of DLC QPL premium performance requirements:
Rated life (L90) of 50,000 hours or greater
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 building energy savings of about 1%, with payback in a year or less due to the 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 trespass.
Group exterior lights into at least three zones: Building-mounted fixtures, pole-mounted fixtures closest to the building, and pole-mounted fixtures farthest from the building.
When operating hours are known, implement schedule-based controls to turn off, or significantly reduce, all but 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 in unoccupied areas. More granular zoning of large exterior parking areas increases savings, as sensors only active some portion of 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 a time delay adjustment.
Many warehouses and industrial buildings use make-up-air units (MAU) to provide heating and ventilation. Direct-fired MAUs (DFMAU) ignite the gas flame directly in the airstream, avoiding heat exchange losses 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 11% or more in a typical application when using DFMAUs, resulting in a simple payback of less than five years.
DFMAUs add value to a building project, which can increase sale price or lease rates. A typical net present value is +$0.12/gsf.
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 DFMAU heating and ventilation units with a minimum gas heating efficiency of 92% or higher. Consider referencing the following standards in project requirements:
Alternately, buildings that cannot use direct-fired units may specify rooftop units with condensing furnaces with a minimum gas heating efficiency of 96%.
Condensing furnaces and boilers that require condensate drains should be coordinated with plumbing design.
Many warehouses and industrial buildings use rooftop units (RTUs) to provide cooling and ventilation when air-conditioning is required for storage or work areas. 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.
Efficient RTUs are a low-cost energy efficiency upgrade. Units may cost $19 to $65 more per ton of cooling, with an incremental cost as low as $0.05/gsf.
Cooling electricity costs are reduced by 10% or more in a typical application, resulting in a simple payback of less than five years.
High-efficiency RTUs add value to a building project, which can increase sale price or lease rates.
There are two efficiency ratings for RTU air conditioners, EER and IEER. EER (energy efficiency ratio) is an efficiency rating when the RTU is at full load on the hottest day. However, the RTU may be at full load less than 1% of its life.
IEER (integrated energy efficiency ratio) accounts for the RTU's part load efficiency. IEER is a better representation of the energy efficiency of the rooftop unit.
The most efficient air conditioning units have variable speed compressors and fans with integrated controls. These systems can match the exact cooling load required, saving energy over staged compressors, which 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 more energy savings.
If you use a system type other than those listed in CEE's publication, specify rated efficiencies 10% higher than the code minimum requirement.
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 XPS insulation has an incremental cost of $0.33/ ft2. While payback for this measure is 4 to 6 years, the lifetime of the wall system is typically equal to the life of the building itself, often 50 years or more. Gas savings for the building is typically 3% per year and electric 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.
XPS typically is R-5 per inch. It maintains its R-value in cold temperatures. Over time, the R-value will decrease slightly. 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—avoid penetrations though the continuous insulation. This is common around load-bearing 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, further 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.
Warehouses are sparsely occupied but often have a significant ventilation load. Demand-Controlled Ventilation (DCV) can reduce outside air intake when the building is not populated.
Simple DCV consisting of CO2 sensors in the warehouse floor unit 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.
Reducing the amount of outdoor air intake by 50% over the year can save $30 per 1,000 square feet of air-conditioned warehouse floor each year, with a simple payback in three years.
Use CO2 sensors to verify warehouse occupancy. Providing adequate ventilation improves occupant productivity. Alternatively, occupancy sensors may deliver comparable quality and effectiveness.
A certain amount of air ventilation is always necessary to offset exhaust in the warehouse for pollutants and battery charging stations.
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 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. If occupancy sensors tied to the lighting system are used, these will be installed throughout the space or fixture mounted, based on the lighting layout.
ASHRAE 62.1-2016 126.96.36.199 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.
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 the construction costs related to adding solar later by up to 60%.
Solar PV systems perform best when shading from vegetation and neighboring structures is minimized. To the extent possible, site buildings in the least-shaded portion of a lot, designating shady areas for parking and driveways.
Rooftop solar systems weigh 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 photovoltaics (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, the ComEd 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.