Commissioning and energy audits are often confused – both services involve an inspection of the building by consulting engineers, but their objectives are different. Commissioning and energy audits should not be seen as competing options, but rather as complementary services. Obtaining both simultaneously is a smart approach, as consultants can gather all relevant data in a single building inspection.
In simple terms, the difference between commissioning and energy audits can be explained as follows:
- The objective of commissioning is to maintain all building systems operating as specified in the design documents and technical specifications.
- The aim of energy audits is to identify viable measures that improve a building's energy performance by reducing fuel and electricity consumption.
In New York City, energy commissioning and audits are mandatory at 10-year intervals for all buildings covered by Local Law 87 of 2009. This law is part of the Bigger, Greener Buildings Plan, which aims to achieve an improvement in the entire city in energy efficiency, while reducing greenhouse gas emissions.
Increase building performance with commissioning and energy audits.
Building Commissioning
When a construction project is completed, the commissioning process ensures that all building systems operate as specified in the project documentation. Commissioning is also carried out after major renovations, where construction systems undergo significant modifications.
Commissioning a project just once after construction is not enough; When a building starts operating, the performance of its main systems tends to decrease over time. There are many possible causes and below are some examples:
- Mechanical components wear out with use, which impairs performance. In the case of rotating equipment, components can begin to suffer imbalances and misalignments, causing vibrations and noise.
- The configuration of controls and sensors can be accidentally modified during maintenance activities, affecting the performance of building systems.
- Quick fixes and undocumented opportunities for building systems can cause operating conditions that differ from those specified in project documents.
The term retro-commissioning is used when a building has never been commissioned before, or has not been commissioned for a long time. On the other hand, the term recommissioning is used when a building is commissioned at regular intervals. However, both concepts refer to the commissioning of existing buildings.
Commissioning can be considered an attractive investment as it provides an increase in building performance at a relatively low cost. A typical commissioning process involves only skilled labor from technicians and engineers, along with minor repairs and part replacements. There is no major capital expenditure involved in commissioning and the payback period can be less than a year.
A detailed inspection of HVAC installations is very important during the commissioning process: HVAC systems represent the majority of energy consumption in residential and commercial buildings and have many interacting components that can suffer loss of performance over time. Additionally, poorly functioning HVAC systems have poor temperature and humidity control, which is detrimental to occupant health and comfort.
Energy Audits
An energy audit seeks to reduce a building's energy consumption without compromising performance. It involves a building inspection just like commissioning, but the goal is to identify upgrades that improve energy performance by exceeding the operating conditions specified in the design documents.
Some of the most commonly proposed energy efficiency measures are LED lighting retrofits, HVAC replacements, variable speed drives for pumps and motors, automatic controls, and building envelope upgrades.
The two main energy inputs used by buildings are fossil fuels and electricity. Fossil fuels are typically used for space heating, domestic hot water and backup generators, while most other building systems run on electricity.
- Heating systems typically run on natural gas, but some buildings use other fuels, such as heating oil or propane.
- On the other hand, standby generators typically use diesel.
Electricity is not commonly used for heating applications as the operating cost becomes very high. However, modern heat pumps offer high efficiency and can equal the cost of heating gas using only electricity.
There is a wide variety of energy efficiency measures that can be implemented in buildings, and the best options change depending on the condition of the building – measures that are very effective in one property may only produce small savings in another, which is why energy audits are important.
Energy audits may also include a feasibility study for renewable energy:
- Solar photovoltaic systems are economical for most properties, as long as they have an adequate area and are not covered by shadows.
- Wind turbines are more demanding in terms of local conditions. However, they are viable for some properties.
- For buildings with access to large amounts of organic matter, biomass energy can also be an attractive option.
Conclusion
Building commissioning aims to maintain optimal operating conditions in accordance with design documents, while energy audits aim to improve building performance. Many consulting engineers are qualified to offer both services, which saves time because you only need to do one building inspection.
Commissioning and energy audits are recommended at regular intervals as they reduce the operating cost of your building. The commissioning process can also reveal malfunctions in building systems when they are still small, allowing for corrective measures before they cause a serious equipment failure.
