THE HVAC System
Roughed-In & Ready to Finish
Over the past several weeks the heating, ventilation, and air-conditioning (HVAC) system has been roughed-in. Much more than a heat pump and some metal ducts, the HVAC in this home relies upon a systems-design approach that accounts for how the house works as an integrated whole.
When a bedroom door is closed, it affects air flow and energy efficiency in a home. That's why the Concept Home has simple, cost-effective "jump ducts" to give air a return flow path out of closed-off rooms back to the return air duct system.
When the building shell is made highly efficient and air-tight, the house still needs fresh air provided in a simple, reliable fashion. That's why the Concept Home, which will be air sealed with soy-based expanding foam insulation, relies upon a semi-balanced ventilation system which automatically introduces fresh air to the home. The ASHRAE 62.2 compliant system relies upon full-time exhaust airflow from highly efficient and quiet bath fans which supply air into the home controlled by a simple, user-friendly controller from Honeywell.
The HVAC system design from Newport Partners is right-sized to meet the true heating and cooling loads the house will face, not an oversized unit which will be less efficient. This is especially important in a high performance house like the Concept Home. Duct leakage - another energy thief - was designed to be less than 3% of the conditioned floor space area in cubic feet per minute (CFM) at 25 Pascals by sealing all gaps and joints with durable, long-lasting mastic. Preliminary duct testing results performed last week by the Omaha Public Power District indicated we met our leakage goal.
Comfort means good IAQ as well as temperature control. The HVAC system features a high efficiency air filter to remove particulates, exhaust fans in the garage draw contaminants to outside whenever the garage door is operated, and whisper quiet fans for moisture removal from bathrooms.
There's a lot to think about in providing efficient and reliable home comfort. Fortunately programs like Environments for Living - which the Concept Home complies with - provides direction and meaningful requirements for achieving these goals.