November 2, 2015
by Katya Guletsky
An energy audit can help building managers and owners understand and control the costs of operating a building. But what happens during the audit, what does an auditor look for and what techniques do they use? How do they present their recommendations? What would warrant an energy gut rehab?
At the October forum hosted at the Knoll showroom three presenters, each with over 30 years of experience, explained to us the basics of sustainable renovations using a wide variety of case studies ranging from single family homes to energy gut rehabs for multifamily residences.
Andy Padian of PadianNYC Consulting: Sustainable Rehab from Simple to Complex – 12 buildings in 30 minutes
(Click here to view presentation slides.)
Andy Padian is a private Building Science Consultant with 35 years of experience, who has performed energy analysis on thousands of buildings across the country.
Mr. Padian introduced some of the reasons clients want to perform an energy audit: some want to save on energy bills, while others need to identify the causes of serious problems, such as having to replace the roof every 10 years. Some case studies of energy audits that achieved improvements by upgrading building equipment and tightening the building envelope he discussed were:
- A housing complex of 24 buildings/188 units, achieved 50% gas savings by replacing all hot water furnaces, as well as lighting and refrigerators, with energy efficiency models. As a bonus, the vacancy rate went from 20% to 1% because with better efficiency the building was able to maintain warmer temperature in the apartments.
- A historic building converted to senior housing achieved 20% savings by air sealing and insulating the attic, as well as replacing heating and hot water boiler.
- A 35 apartment building reduced the annual oil usage by 67% by doing full weatherization package: replacing the boiler, air sealing, replacing windows, improving insulation and installing better controls.
Other cases required investigation and analysis to identify the problem:
- An energy auditor was called to a townhouse due to a crack in the bedroom ceiling. By following the clues the auditor uncovered the problem causing the roof to overheat and leak. The house also turned out to have several major air leaks through doors and windows, a very inefficient boiler and a wasteful shower.
- An electrically-heated apartment building had demonstrated a stack effect: hot top floors and cold low floors, even though the owner insulated exterior skin and windows prior to the audit. The energy audit improved the balance of the ventilation system which adjusted the heat distribution.
Some problems could be uncovered via modeling and testing:
- Apartments in a senior apartment complex were cold and drafty, and there was a bad smell in the hallways. Modeling identified air and water leakage problems and the blower door test identified air leakage areas. Air sealing measures achieved 24% CFM reduction and 25% electrical savings. By sealing kitchen and bathroom sinks and bathroom sheetrock penetration, they achieved 46% reduction in gas use, and 21% in water use.
No less important than the audit itself is the presentation of the findings and recommendations to the client. A good energy audit document should be concise: it should have an executive summary describing the building, the equipment in the building, the identified problems, the proposed solutions, plus an estimate for the proposed Scope of Work. The most important measure that the client should pay attention to is Savings to Investment (SIR). If modeling has been done, there should be a brief and clear summary of the results, preferably in graphic form.
Takeaways from the presentation:
- Energy audit is not always just about energy savings, it is also about preservation and resiliency. Small changes make a big difference.
- Many of the energy waste problems result from inefficient equipment, also from poorly or improperly done insulation and ventilation.
- Most of the energy waste problems can be resolved by tightening the building envelope and fixing or upgrading the ventilation.
- Do energy modeling to uncover and subsequently fix air leakage and mechanical airflows.
- Energy audit also creates non-energy benefits: improved indoor air quality (IAQ) and reduction or elimination of drafts.
Bob Gardella and Mark Yuschak of the AEA: Gut Rehabs – Simple to Complex
(Click here to view presentation slides.)
Association for Energy Affordability (AEA) is a leading provider of technical services for energy efficiency in buildings. AEA’s services include energy audits, modeling, project work scope and specification development, construction management, benchmarking and energy usage monitoring, and green building design services for high performance new construction.
Bob Gardella started by discussing the main reasons a client decides to undertake a gut rehab. The most common are the need to reduce energy use and costs; problems with indoor air quality (IAQ) and indoor comfort; program or incentive requirements, or to achieve a certification, such as LEED, Passive House, Energy Star or others.
Mr. Gardella and Mr. Yuschak demonstrated some of their recent energy gut rehab projects with case studies:
- A single family home on Staten Island was severely damaged from Super Storm Sandy and needed to be rebuilt. The rebuild of the house allowed an opportunity to include energy retrofit measures: two part foam insulation on interior walls and rim joists, installation of sheetrock/tape.
- A single family home in Brooklyn underwent a deep energy retrofit to Passive House standards: replaced the steam boiler; installed foam insulation interior walls and rim-joists; installed cellulose insulation exterior walls and cockloft; installed triple pane windows and urethane doors; installed Mitsubishi Mini-Split system and Zehuder ventilation unit. The resulting air sealing reduction went from 6,665cfm to 1,896cfm
After describing the Passive House project in detail, they talked at length about the Passive House standard, which is steadily moving from a boutique approach to mainstream.
Mr. Yuschak addressed some common Passive House myths and counteracted them with actual facts. For example, it is not true that you cannot open windows in a Passive House, and that, because it is airtight, the IAQ is bad. It is also not entirely true that it is too expensive to build. In fact, a Passive House has a major emphasis on IAQ and indoor comfort, and the air quality is much better than in a conventionally built home due to superior ventilation. A Passive House focuses on the building envelope and demands very high quality of construction. It can achieve an 85% reduction in heating and cooling. And a Passive House standard can be applied to any type of building: a house, an apartment or an office building.
The success factors for a Passive House project:
- The most important is the coordination between trades: proper logistics and sequencing of operations is critical.
- The second most important is to have a person who knows what they are doing, and that means experience with Passive House projects, not merely taking a class.
- Combination of Passive House with other certification standards, such as LEED, Energy Star etc., works very well, as they complement and complete each other: each addresses some areas that the other does not.
- It is very important to do testing to verify the performance: blower door; duct blaster; zonal pressure diagnostics; fan flow; CAZ testing for air quality; combustion safety (some of these tests are required by code).
This was a very interesting and educational forum and we would like to thank all our speakers for showing to us how to achieve significant building performance improvements, as well as improvements in IAQ and comfort level, through properly executed energy audit and rehab.