Deep energy retrofits can often reduce the energy consumption of buildings by 50% or more. Considering their scale and cost, these retrofit projects must be planned and designed carefully to maximize their return on investment. However, there are many simple and low-cost energy efficiency measures that can be deployed as a first step before a major retrofit.
Energy Efficiency Measures with a Low Cost and Quick Payback
Each building is unique, and the optimal combination of energy efficiency measures will change accordingly. Also, the measures identified during an assessment can vary a lot in terms of cost and payback period. However, this article will provide an overview of low-cost measures that are effective in most buildings:
- Upgrading to LED lighting, which saves on both energy consumption and maintenance.
- Adding automatic controls for lighting fixtures, HVAC and other building systems.
- Upgrading to water-saving plumbing fixtures.
- Creating an energy efficiency program to raise awareness among the building management personnel.
- Even greater savings are possible if all building occupants can adopt energy efficiency habits. This accelerates the payback period of energy efficiency measures.
According to the ENERGY STAR website from the US Environmental Protection Agency, a commercial building typically wastes 30% of the energy it consumes. However, a study by the University of California Davis and the California Air Resources Board found that buildings can reduce energy consumption by 5% to 30% with low-cost upgrades, but these are often ignored.
By focusing on simple and low-cost energy efficiency measures first, building owners can start saving energy with relatively little effort and investment. The savings achieved can then be used to help finance other energy efficiency measures.
Large buildings can often achieve significant savings with recommissioning: inspecting all equipment and installations to make sure they operate as intended, while making minor adjustments and repairs. According to the Canadian Department of Natural Resources, recommissioning can normally reduce energy consumption by 5 to 15 percent, while having a payback period of less than three years.
Savings achieved by a Texas University with just control adjustments.
Why Energy Experts Recommend LED Lighting
Lighting upgrades have a significant potential to save energy in commercial buildings. According to the US Department of Energy, commercial buildings have 25% of the lighting fixtures in the country, but they account for 50% of lighting energy consumption. For comparison, residential buildings have 71% of the total lamps, but only 25% of lighting energy consumption.
A study by the California Energy Commission found that 50% energy savings are typical after upgrading to LED lighting. Another study by the University of Toronto found that lighting upgrades alone achieved 30% average savings in 80 office buildings.
LED lighting is among the most frequently recommended upgrades, and there are several key reasons:
- A lighting upgrade is quick to install while causing minimal disruption. For comparison, measures like a window replacement or an HVAC equipment upgrade are much more disruptive.
- There are LED retrofit kits that reuse the existing housings and lampholders. With this upgrade option, there is no need to open the ceiling and remove entire fixtures.
- Also, since LED lamps consume less power, they draw less current than the lamps they upgrade. If the existing wiring is in good condition, there is no need to replace it.
High-quality LED products normally come with a warranty period of five years or more, while their payback period is often less than three years. In buildings with extended operating schedules, the payback period of LED lighting can even be less than one year. Since the warranty period is typically longer than the payback period, LED lighting can be considered a safe investment. With a solid warranty, any lamps that fail are replaced for free.
LED lighting also leads to a slight reduction of air conditioning expenses during summer, since it emits less heat than older types of lighting. The same benefit applies when the lighting is upgraded to LED in a cold storage facility. The effect of one lamp may be small, but large commercial buildings may have thousands of them. Consider the following example:
- T8 fluorescent tubes are commonly used for office lighting, and 4-feet T8 tubes typically consume 32 watts each.
- LED versions of these tubes consume as little as 15 watts (the exact power rating depends on the manufacturer).
- Assuming 15W per tube, the difference in power consumption is only 17W. However, if 5,000 of them are replaced in a large commercial building, 85 kilowatts are saved.
- If these lamps operate for 2,200 hours per year, 85 kW of power savings translate into 187,000 kWh of energy savings. With an electricity price of 0.10 US$ per kWh, this is equivalent to savings of $18,700 per year.
LED versions of T8 tubes can now be obtained for less than $10 each, which means the upgrade above can be completed for less than $50,000. Based on the estimated savings, the payback period is less than three years.
Since the LED tubes provide equivalent lighting, most of the savings are due to reduced heat emission from the lighting system. These 85 kilowatts of power are not only subtracted from direct electricity consumption, but also from the cooling load of the air conditioning system. The lighting savings are known directly in this case, but energy modeling could be used to estimate the air conditioning savings as well. Even greater savings are possible if an LED lighting system is operated with smart controls:
- Occupancy sensors can be used to detect when lighting fixtures are on in an empty room. In these cases, they can be switched off automatically.
- Daylight sensors can be combined with dimming systems, to reduce the artificial lighting output in response to the available daylight. If a specific area of the building is getting enough lighting with daylight alone, the LED lamps can be switched off.
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Adding Automatic Controls to Existing Equipment
Many automatic controls have a superficial installation, which means they can be deployed with little disruption just like LED lamps. Automatic controls can also achieve a quick return on investment, since they use existing equipment more efficiently.
When automatic controls are used in HVAC systems, they can also improve indoor air quality while saving energy. For example, if the ventilation rate is controlled according to air quality measurements, less fan power is consumed when indoor air is clean. Depending on the time of the year, this also means having to cool or heat less outdoor air.
- The University of Toronto study found that ventilation optimizations can reduce heating and cooling costs by around 50%.
- The study mentions the case of a Texas university that reduced ventilation costs by 59%, cooling costs by 63%, and heating costs by 90%. The project also involved a major retrofit, but half of the savings were achieved with control adjustments only.
The potential savings with automatic controls will depend on compatibility with the existing installations.
In the case of HVAC systems, the compatibility with smart control varies because there are many possible configurations. For example, a variable air volume (VAV) ventilation system can be easily automated, since it already has the capacity to reduce and increase airflow. On the other hand, a constant air volume (CAV) ventilation system must be converted to VAV first, or equip it a variable frequency drive (VFD), since the airflow cannot be adjusted.
Quick Solutions for Building Envelope Issues
The building envelope is responsible for keeping heat outside during summer and inside during winter. When the envelope cannot perform this function effectively, air conditioning and heating systems must work harder to compensate. Upgrading the building envelope requires major changes to walls, rooftops, windows and other components, making it a capital-intensive project. However, the US Department of Energy recommends quick measures that fix localized insulation problems or air leaks:
- Spray foam insulation
- Caulking, to seal air leaks in fixed building elements
- Weatherstripping, to seal air leaks around moving elements like doors and windows
According to the US Department of Energy, these simple air sealing measures normally achieve a payback period of less than one year.
Ventilation optimizations can reduce heating and cooling costs by around 50%, though they require a variable air volume (VAV) system or a constant air volume (CAV) one equipped with a variable frequency drive (VFD), so the airflow can be adjusted.
Upgrading to Water-Saving Plumbing Fixtures
Upgrading the plumbing fixtures may not seem like an energy efficiency measure at first. However, consider that many buildings use pumps to distribute water internally, and many applications require a water heater.
- When water consumption is reduced, the energy consumption of pumping and heating systems is also reduced.
- The heating savings apply for small-scale heaters in individual dwellings, and also for centralized boiler systems. In both cases there is less water flowing through the heating unit, requiring less BTUs of heat input.
A simple way to upgrade plumbing fixtures is looking for the WaterSense label from the US Environmental Protection Agency (US EPA), which means the product has been tested for water savings of at least 20%.
Upgrading to water-saving plumbing fixtures in a building is relatively simple, since they are superficial components of the plumbing installation. In particular, WaterSense fixtures with the US EPA label are designed to replace older fixtures with no need to upgrade pipes and other hard-to-reach components.
Creating an Energy Efficiency Program
Energy efficiency measures often suffer from a rebound effect. Once they are installed, users become less careful with saving energy, since they are aware that the building became more efficient. Unfortunately, this reduces the effectiveness of energy efficiency measures. Consider the following examples of the rebound effect:
- Not worrying about turning off the lights, since they are efficient LEDs.
- Setting the thermostat lower in summer and higher in winter, since the HVAC system became more efficient.
Energy consultants recommend an energy efficiency program along with any building upgrades, to maximize their benefit. If equipment upgrades are combined with energy-saving habits, their return on investment can be even higher than estimated.
Desktop computers, printers and other types of office equipment have a power-saving mode that is not always used, and activating this mode requires zero investment. For example, monitors can be configured to enter standby mode automatically when they are not being used.
Beyond Low-Cost Energy Efficiency Measures
This article focuses on low-cost and quick-payback measures to save energy in buildings. However, energy modeling is strongly recommended for deep retrofits and new constructions. In 2017 the American Institute of Architects published a report on building energy efficiency. When discussing energy modeling, the report compared 3,801 non-modeled projects with 3,857 modeled projects. All of them included energy efficiency measures, but the results differed:
- Non-modeled projects reduced energy usage by 37% with the measures deployed.
- However, modeled projects achieved 52% energy savings.
In other words, energy modeling increased the effectiveness of energy efficiency measures by 15% in the projects covered by the study. According to a study by National Grid, the average US office building spends $1.34/sq.ft. on electricity and $0.18/sq.ft on natural gas each year, for a total of $1.52/sq.ft per year.
- Based on these figures, a 50,000 sq.ft. office building spends $76,000 per year on electricity and gas bills.
- For this building, 37% energy savings are equivalent to $28,120 per year, while 52% energy savings are equivalent to $39,520 per year.
In this example, the 15% additional savings achieved by energy modeling are equivalent to $11,400 per year.
Not all energy efficiency measures involve a major expense for building owners. Some of them have a low cost, simple installation and quick return on investment. For example, LED lighting upgrades, smart controls and simple building envelope fixes are effective in most cases. Water-saving fixtures can also achieve quick energy savings in buildings that rely on pumping systems, or buildings that use plenty of hot water.
- LED lighting often achieves a payback period of less than three years. In buildings with old lighting systems or high electricity tariffs, a payback period of less than one year is feasible.
- Simple building envelope repairs and control measures can also achieve payback periods of less than one year.
- UC Davis and the California Air Resources Board estimated that low-cost measures can reduce building energy consumption by up to 30%.
Smart controls have the potential to increase the performance of any building system, by using the existing capacity more efficiently. Control measures prevent issues like excessive lighting, overventilation, overheating, overcooling or pumping water at excessive pressure – all represent a waste of energy.
Raising awareness among building occupants is also important: energy efficiency measures achieve greater savings if occupants also adopt energy conservation habits. When energy efficiency measures are combined with conservation programs, the energy savings are higher and the payback period is quicker.
Indoor comfort and energy savings on autopilot
Thermal comfort and indoor air quality are very correlated to staff health and cognitive performance, studies say.
Since human resources are businesses’ largest expense, it’s time to give them the best.