The Difference Between Energy Audits & Commissioning in NYC LL87

The terms commissioning and energy audits often come up when we talk about building inspections. The terms are often confusing to most, but their goals are different. Commissioning and energy audits are not competing options, but are complementary services. Opting for both the services is often beneficial for most buildings, since consulting engineers can get all the relevant data about building system operation and energy performance in a single inspection.

In simple words, both the terms can be explained as follows:

• Building commissioning involves keeping all the building systems operational as specified in the design documents and technical specification.
• Energy audits aim to identify measures that effectively improve the energy performance of the building.

In some cases, commissioning can also be thought as the follow-up to an energy audit. In these cases, energy audit identifies opportunities that would need commissioning as the follow-up.

In an attempt to cut down the greenhouse gas (GHG) emissions, New York City came up with Local Law 87 which mandates commissioning and energy audits of buildings larger than 50,000 sq. ft. in 10-year intervals. Local Law 87 is a part of the Greener, Greater Buildings Plan (GGBP).

Now that you know a bit about commissioning and energy audit, let’s take a look at them in details.

Building Commissioning

Commissioning of a building involves ensuring that the building systems operate as specified in the design documentation. Commissioning is also often carried out after major renovation. Commissioning of buildings only once is not enough as the system tend to deteriorate over time. This is also one of the reasons why LL87 mandates commissioning along with energy audits once in every 10-year period.

There are many reasons for building systems to deteriorate over time. Some of them are:

• Wearing down of mechanical components with use over a long period of time.
• Accidental modification of controls and sensors affecting the building system performance.
• Undocumented changed in building systems causing them to operate differently than as specified.

When compared to energy audits, commissioning is often said to be an attractive investment since the associated costs are low. A typical commissioning process involves skilled labour from engineers along with minor replacements and reparation. Since there are no major expenditures involved, the payback period is less than 1 year.

Terms like recommissioning and retro-commissioning often cause a lot of confusion. The term retro-commissioning is used for buildings that have never been commissioned before, or not in a very long time. Recommissioning, on the other hand, is used for buildings that are commissioned at regular intervals. Both the terms refer to commissioning of existing buildings.

Energy Audit

Energy audit aims to understand the current energy consumption profile of the building and identify upgrades to reduce the energy consumption without compromising performance. Energy audit involves building inspection just like commissioning, but the goal is to improve the energy efficiency by exceeding the operating conditions specified in the design documents.

The most common energy efficiency measures are:

• LED lighting retrofits
• HVAC upgradation or replacement
• Variable speed drives for pumps and motors
• Automatic controls
• Building envelope upgrades

Apart from building equipment upgrades, building energy inputs play a vital role in improving efficiency. Fossil fuels are commonly used for space heating, backup generator, and domestic hot water, while other systems use electricity.

Depending on the building requirements, energy efficiency measures vary. Thus performing energy audit is crucial for identifying the energy efficiency measures.

To tackle the environmental footprint of fossil fuels and high prices of electricity, below are some of the renewables that promote energy efficiency while reducing the costs associated:

• Solar panels are very cost effective for most properties. With a service life of over 25 years, they provide excellent cost effective alternatives for energy sources.
• Wind turbines couples with energy storing batteries are gaining demand due to their low-cost electricity production.
• Biomass power is an attractive alternative for buildings with access to abundant organic materials.