The first step toward energy efficiency requires that a building be benchmarked. Benchmarking allows a building owner or auditor to compare the subject building’s energy efficiency with similar-use buildings throughout the US. Two years of utility data are collected and analyzed, and can then be uploaded into the US Environmental Protection Agency (EPA) database. The EPA’s Energy Star Portfolio Manager is a very large database of benchmarked buildings; as of 2010 it contained more than 185,000 buildings totaling 21 billion square feet. An auditor can also use interval data (electrical usage in increments as small as every 15 minutes) to analyze electrical demand and recommend efficiency improvements, many of which have a zero or low cost of implementation.
The second step is an energy assessment, commonly called an Energy Audit. Defined as “the methodical and systematic process of quantifying all aspects of your building’s energy consumption and recommending non-capital expense energy conservation measures (ECM’s) and capital-expense energy efficiency measures (EEM’s) that are justified by a financial return.” The American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE) defines three levels of energy audits, Level 1 being a cursory walk through, Level 3 being an in depth, thorough and comprehensive evaluation of all of a building’s systems and Level 2 falling between Levels 1 and 3. Level 3 audits also require that the building be modeled in an energy modeling software package to allow the efficient exploration of various efficiency retrofit scenarios. An investment grade audit (IGA) typically falls into the Level 3 category; it requires the calculation of the capital cost and expected return on capital invested for each EEM recommended.
The typical audit process includes benchmarking, a building plan review, a site survey, modeling the building’s energy use in software, reconciling the model with the building’s benchmark consumption, identifying and researching possible EEM’s and ECM’s, performing the necessary technical and financial calculations required to justify or eliminate the recommendation, researching utility provider incentives and rebates and compiling the results in a comprehensive report.
Level 2, 3 and IGA’s require that the auditor have an understanding of the local climate, the building’s occupancy and use and the building’s equipment use. It includes investigation of systems including heating ventilation and air conditioning (HVAC), electrical and lighting, plumbing fixtures, energy management systems, and all the equipment used in the building.
Summary of the steps of an audit:
Benchmarking: If you have not already benchmarked your building, we can do it for you. Benchmark data is used to develop efficiency indexes including your building’s Energy Utilization Index (EUI) and Energy Cost Index (ECI). These indexes allow the comparison of your building with other similar-use buildings in the area, from the perspectives of energy use per square foot (kBTU/sq ft) and energy cost per square foot ($/sq ft) of building. The data is also analyzed for anomalies and trends. This Several cities including Seattle, San Francisco, Washington DC, Austin, Philadelphia and New York require large building owners to benchmark their buildings annually and publish the results in the EPA Portfolio Manager database. 24 months of utility bills are obtained from the building owner or with authorization, from the utility provider. The data is plotted and evaluated for trends and/or anomaly’s.
Plan Review and Climate Data: Current building plans including architectural, mechanical, lighting and electrical plans and schedules are obtained and reviewed. Climate data for the site are obtained, including heating and cooling degree days and seasonal design temperatures.
Site Survey: The auditor will interview on-site personnel including the plant, facility or maintenance manager and other key personnel. He normally walks through every room in the building, validating equipment nameplate data, HVAC and lighting schedules, noting all equipment in use, plug loads and plumbing fixtures. Building occupancy, equipment use schedules, HVAC and lighting control settings, building shell condition, insulation values and air infiltration are evaluated in light of potential recommendations. A site survey’s can take from 2 hours to 3 days, depending on the size, use and complexity of the building.
Research: Every building has a unique energy consumption profile and each brings with it different questions requiring research.
- are there more energy efficient models of specialized machinery available
- are retrofits available for fan motors, HVAC controls, plumbing fixtures and lighting and lighting controls that didn’t exist when the building was constructed or last renovated
- is it necessary to bring in deeper expertise to evaluate certain building systems like ice rink refrigeration or swimming pool filtration
- what is the current state of the art (lighting technology, for example, is rapidly changing) of available retrofit technologies
Specialized equipment in use, building construction, maintenance issues, building systems and the local environment all require thorough research in order to make informed, realistic EEM recommendations that are accompanied by concrete savings and costs.
Energy Modeling: The building is modeled using specialized building energy modeling software. Actual energy consumption is reconciled with the building model, allowing the auditor to evaluate various EEM recommendations for effectiveness, savings and ROI. Occasionally the software is not capable of modeling an EEM, in this case calculations are performed manually, outside of the modeling software.
Financing Research: Our auditors have compiled lists of funding sources; some may be available to you. They include utility provider rebates, tax deductions and government grants and loans. This information, as appropriate, is included in the financial analysis included in the report. In some cases, our auditors can be retained to submit applications to these funding sources.
Reporting: A report is produced, presented and reviewed with the client. Reports include an executive summary providing a high level building overview and summarized EEM and ECM recommendations including estimated costs, annual savings and ROI. A detailed documentation of all building systems follows, as well as detail for each recommendation. Manufacturer sources and spec sheets are included as appropriate, to provide the client with sources for upgraded equipment.
Client Review: The report is reviewed with the client and adjustments and/or corrections are made; recommendations may be re-prioritized based on client feedback, and the report revised accordingly.
This is typically the end of the energy auditing process. Some building owners request a follow-on step to assist with implementation. In these cases, we work with the building owner/operator to develop a strategy and plan for implementation based on available grants, rebates, public utility incentives or match funding and the client’s internal finances and business objectives. Definition of a scope of work and solicitation and qualification of contractors may also be included.
Annual energy savings, as a percentage of annual energy costs, can vary from 5% to 50% and payback (of investment) periods can vary from 1 month to 20 years, depending on the age of the building, what improvements have already been made, utility rates, etc. Based on our experience, it is safe to say that we can help every owner recognize a 10-20% reduction in energy cost in an older building that has not already had an energy management program put in place, with a 2-3 year payback on most capital improvements. The cost of an energy audit is typically recovered within the first year, if the high priority recommendations are implemented.
These energy audits were performed by Jim Fowler, as Principal and Partner in Energy Audits of Alaska, our sister company serving the state of Alaska.