Monday, July 25, 2016

NW Code Requirements

The State of Washington has issued a new building code that affects, among other spaces, office buildings. The code is very specific about ventilation and building energy use in that it mandates “the use of decentralized ventilation systems using dedicated outdoor air systems (DOAS) to deliver 100 percent outside air independent of heating and cooling systems”.

What this means is that DOAS systems are mandated and that conventional VAV systems, which mix ventilation and return air at an air handler, are essentially prohibited. While there is an exemption for “High Performance VAV systems”, which I have described in an ASHRAE Journal article and in earlier blogs, it tends to favor those that are disconnected from the ventilation supply, such as VRV and chilled beams.

What is particularly interesting is the requirement that states “ECM motors that vary with load are required for all fan powered VAV terminal units”. This, of course, is what I have been advocating for some time – variable volume series fan box control. When employed with 100% outside air through the VAV inlet (and a sensible cooling coil on the induction port), all the requirements of the new Washington code are met. I’m willing to bet that this will not be the only such code requirement that we’ll see in the future.

Authored by: Dan Int-Hout, Chief Engineer Krueger