All buildings over 50,000 sf must file an Energy Efficiency Report (EER) with the New York City Department of Buildings. The EER consists of an ASHRAE Level II energy audit and retrocommissioning study of base building systems. EERs are due once every 10 years, starting in 2013 in a staggered schedule based on the last digit of the building's tax block number. Base building systems must include systems of subsystems that use energy or impact energy consumption including: building envelope, HVAC systems, conveying systems, domestic hot water systems, and electrical/lighting systems.
PROCESS: ENERGY AUDIT
Audits closely examine and evaluate the existing energy infrastructure of a building and shoe building managers where money and energy are being spent. They help identify trouble spots and methods for improving performance. Energy audits will typically result in recommendations for tune-ups and/or upgrades to equipment. Alterations can be as simple as changing light bulbs or as complex as overhauling the heating and cooling systems. Here is what an energy audit will accomplish at a minimum:
- identification of all reasonable measures and potential capital improvements that can reduce the cost of building operations;
- the associated annual energy savings, the cost to implement, and the return on investment;
- the building's benchmarking output consistent with the US EPA's Portfolio Manager;
- a breakdown of energy usage by system and predicted energy savings after implementation of proposed measures;
- a general assessment of how the major energy consuming equipment and systems used within tenant spaces impact the energy consumption of the base building systems.
An energy audit helps the owner or operator to understand the energy use characteristics of their building. It breaks down total energy use and cost into various end uses, such as heating, air conditioning, or lighting and shows the potential for savings. The report provides the owner or operator a list of energy conservation measures (ECMs) and follows a systematic approach to identifying, selecting, and ranking recommended measures. In many cases, different levels of energy audits can be performed with various results; however, for the purpose of complying with Local Law 87, an ASHRAE Level II energy audit must be performed. It is relatively comprehensive but not terribly difficult or expensive to execute.
In the report, each ECM will have a cost and specific return on investment (ROI) associated with it in order to help the owner prioritize and make an educated business decision about which to implement. The goal of the audit is to reduce energy consumption in the building by giving owners detailed analysis so they can make informed business decisions. The following outlines all of the tasks that must occur to achieve Level II status:
- Preliminary Energy Use Analysis includes identification of space types and utility bill analysis. It generates an Energy Utilization Index (EUI) and compares the facility to similar buildings. This is much like the benchmarking with Energy Star.
- Level I: Walk-Through Analysis includes investigation if operational practices via interview, space function analysis, rough estimates of energy end-use. It identifies low or no cost changes to the facility or O&M procedures and potential capital improvements for further study. It provides an initial estimate of potential costs and savings.
- Level II: Energy Survey and Analysis includes a review of mechanical, electrical, and plumbing design and operation, maintenance problems and compares key operating parameters to design levels. It gives a breakdown of annual energy by end-use and provides recommendations for equipment modifications and operational improvements, as well as a financial and cost analysis of all recommended measures.
Energy auditing is an excellent way to develop a capital improvement plan. Replacing outdated equipment with more energy efficient options can dramatically reduce energy costs over time. However, first costs tend to be higher and ROIs longer than those of retrocommissioning.
Retrocommissioning is a systematic process for optimizing the energy efficiency and operations of existing base building systems. Adjustments that occur throughout this process include, but are not limited to, repairs of defects, cleaning, adjustments of valves, sensors, controls or programmed settings, and/or changes in operational practices. These items are typically low-cost or no-cost measures that yield a high ROI. Median commissioning costs: $0.30 and $1.10 per square foot for existing buildings and ROIs typically exceed 15% with payback usually between one and four years. In some cases, clients have seen cash-on-cash returns of nearly 100%.
During the retrocommissioning process, building systems are inspected for physical, functional, and performance conditions. All issues are documents and presented in a comprehensive report to the owner. Diagnostic test equipment is used to assess existing opportunities for energy conservation that normally would not be identified in the audit. Local Law 87 requires the following base building energy systems to be investigated:
- Electrical and lighting
- Domestic hot water
- Building envelope
- Conveying systems