When property managers are considering energy efficiency measures, one electrical engineering question is always present: What is the project budget and payback period? Building upgrades with a shorter payback are normally given priority, since the funds they save become available sooner. A short payback also means the measure achieves high savings relative to its cost – more dollars returned per dollar spent upfront.
If you want to improve the performance of your building and are looking for a quick payback period and a high return on investment, consider the following options. This article will provide a brief overview of each one.
- Lighting upgrades
- HVAC controls
- Power factor correction
Retro-commissioning involves an in-depth inspection of all building systems to identify worn components and wrong configurations. Building systems are cleaned and repaired, while configurations are modified as needed. Components that are beyond repair are replaced, but capital expenditures are less than in building upgrade projects – most of the retro-commissioning cost is composed of engineering services and skilled labor.
The potential savings of retro-commissioning vary by project, but payback periods of less than one year are common. A retro-commissioning project is also an excellent chance to perform an energy audit, which can help property managers identify the most promising upgrades. The measures suggested in this article tend to have the shortest payback period, but not all buildings are equal – only an energy audit can tell which measures are the best in each case. If you are unsure of your building’s status, it is wise to recruit the assistance of an electrical engineering professional.
2) Lighting Upgrades
Of all major building systems, lighting installations are generally the easiest to upgrade. New lighting fixtures can normally be installed without replacing the existing wiring: it was capable of powering the older and less efficient lighting, so it actually ends up with spare capacity after the upgrade.
Some LED products are even designed to use existing fixtures. They may need rewiring or ballast changes, but the fixture body is conserved. The project is faster and less expensive when existing fixtures are used, but full fixture upgrades offer an extra 10-20% savings in most cases.
LED lighting yields even greater savings in air-conditioned spaces: since it emits less heat than older lighting technologies, it also reduces space cooling loads. The effect is minimal in small properties but adds up in large constructions with thousands of lighting fixtures.
The Greener, Greater Buildings Plan requires all buildings covered by Local Law 88 to upgrade their lighting systems by 2025, according to the requirements of the Energy Conservation Code. Nevertheless, regardless of legal requirements, lighting upgrades are among the best building upgrades available.
Depending on building characteristics and location, some properties are eligible for free LED upgrades. In this case, the payback period is eliminated, and net energy savings are immediate!
Submetering is an interesting measure because it does not save energy directly. However, tenants tend to consume less energy when they are submetered, and this applies for both residential and commercial spaces.
- When tenants are not metered, energy expenses are normally allocated based on floor space, but not everyone consumes the same amount of energy per square foot.
- Tenants who waste energy affect everyone, while tenants who invest in efficiency have to share their savings. Thus, this arrangement does not incentive energy efficiency.
- Separate metering creates a greater incentive for savings, since each tenants pays for the energy consumed. Inefficient energy users bear the full cost of wasting energy, while efficient users keep the full savings.
Just like lighting upgrades, submetering is mandatory in some area properties covered by LL88. Both upgrades can be deployed together to save time.
4) HVAC Controls
Major HVAC upgrades are capital-intensive and tend to have a longer payback period that other measures described in this article. However, HVAC controls are relatively simple to install and offer a much quicker payback.
Smart thermostats can be a great choice in multifamily buildings or where commercial spaces have separate HVAC systems – they get rebates of up to $185 per thermostat from Con Edison.
5) Power Factor Correction
Not all the power drawn by a building from the grid is actually consumed. The component that is used is called real power, but there is also a fluctuating component called the reactive power. However, while the reactive power is not used, it adds load to transformers and also causes heat losses in conductors. For this reason, Con Edison applies an extra charge for excessive reactive power in many of its tariffs.
Capacitors can be used to offset the reactive power of a building, causing the reactive energy to fluctuate locally, not between the building and the power grid. This measure is called power factor correction and can often achieve a payback period of less than one year.
Note that power factor correction does not reduce energy consumption, but it does reduce the power bill by eliminating the extra charge applied by Con Edison. Therefore, it is often suggested along with energy efficiency measures.
Additional Electrical Engineering Recommendations
When it comes to building upgrades, there are no “one size fits all” solutions because each property is unique. The measures described in this article tend to offer a short payback period in most buildings, but there are exceptions. The opposite also applies: capital-intensive measures with payback periods that are typically long may offer improved performance if the building is particularly inefficient, or if they qualify for financial incentives.
The best recommendation before proceeding with any building upgrade, not only energy efficiency measures is to get a professional assessment from someone experienced and licensed in electrical engineering.