Builders’ Circle Blog: HVAC – the Vast Unknown
Jim Baker 03/29/2012
We all love to untangle a mystery, and building “green” can be a mystery. But things are changing. In the last ten years Building Science and applications in the field have come together so that the buying public knows many of the right questions to ask. They know about Blower Door tests, HERS ratings, R-values, U-values and all that stuff that makes houses energy efficient. That is, except for the deep, dark, vast unknown technical jungle of the HVAC world.
The average buyer knows the term "heat pump" or that a "high efficient" gas furnace is important, but he will usually struggle with acronyms like ASHP, GSHP, or Dual Fuel Systems. And unfortunately these Air Source Heat Pumps, Ground Source Heat Pumps, and gas furnaces combined with ASHP and GSHP do not come in just one efficiency level. SEER and EER ratings, COP and HSPF numbers, EF factors....make it a jungle of information, all which is of critical importance.
The real darkness, however, comes with the distribution system. HVAC equipment and the related duct systems that deliver "conditioned air" correctly to the right place must be designed to Manuel J, D, and S standards, to be balanced. The system must meet ASHRAE 62.2 ventilation requirements, not to mention ASHREA 90.1, ASHRAE 55 and 52. Confused yet? As you can tell there seems to be a mysterious secret encoded in all these letters and numbers.
So what is my point? The point is simple; HVAC systems, to correctly condition the air in our new high-efficient homes, must have all these technical features designed perfectly and specifically. The old rule to just “oversize it” a ton or two can cause all kinds of indoor air quality issues, even helping support mold growth.
Because of the affordable NAHB Green Verified, and ENERGY STAR certified homes becoming more and more efficient, the pressure is on the HVAC companies to keep up. I have been amazed at the effort given by those HBA members and HVAC specialists who have solved the complex issues in the HBA-led Habitat houses in Builders' Circle. They have taken the unknown, and made it work for the good of the industry.
These companies have the experience and ACCA certification needed for ENERGY STAR V3. ACCA stands for Air Conditioning Contractors of America and requires a high level of knowledge to be a member. Not all jobs require ACCA Certification, but many HVAC companies are attaining certification to get the education and expertise needed for our new era of high-tech homes. NATE and BPI certification are also becoming necessary to produce the needed results for survival in this dark jungle of HVAC acronyms and technical expertise. While learning the meaning of acronyms are sometimes a “pain” and source of confusion, the science behind them all is the key to this new generation of homes we are starting to produce.
Jim D. Baker, B and G Drafting – HERS Rater and NAHB Verifier on this project.
In January 2011, the HBA of Greater Springfield announced it would partner with Habitat for Humanity of Springfield to build the first two homes in Habitat’s new Builders Circle development. The homes will be certified to the National Green Building Standard and their construction will serve as a demonstration of flexible and affordable methods by which construction professionals can build green in a residential setting.
Jim Baker (B&G Drafting) is a Certified Green Professional (CGP), a HERS Rater, and a certified NAHB Green Building Verifier. He also helped design these and other green-built homes throughout the area. This Builders Circle Project Blog helps keep HBA industry professionals and curious consumers up to date on the latest green building features being incorporated into the project. The blog also provides updates on the project’s latest progress and upcoming needs. Those who would like to help with the project are encouraged to leave their comments at the end of blog posts, or on the project's facebook page, to offer your assistance.