Codes require energy modeling for residential compliance
You may have heard that energy codes are ramping up. Architects can better serve their clients by having an awareness of code changes with designs that cost-effectively meet code requirements, leverage generous new construction rebates, and avoid the expense of code non-compliance. Since it's a lot to navigate, a qualified energy engineer or HERS rater is invaluable for navigating the code changes. Energy efficient building- which is quickly becoming mandatory- begins in the design stage, not on the job site!
2012 IECC and a new Stretch code on the horizon
The current Stretch Code, currently base-code for a growing number of Western MA communities, achieves a 20% improvement in building performance over the base 2009 IECC code. The 2009 IECC has been referred to as the training wheels for the 2012 IECC, which is weeks away from being adopted in Massachusetts with an expected 12 month concurrency period. The Stretch Code will then be revamped to exceed the 2012 IECC levels. This suite of 'advanced energy codes' will create buildings that are ready for what I like to call the 'low energy future.'
What is a Home Energy Rating (HERS) ?
The Stretch Code currently requires a performance path for compliance for residential new construction using a confirmed HERS rating. A HERS rating involves detailed energy modelling of the home, site inspections, and diagnostic testing. It is an asset rating, meaning that all fixed elements of the home are factored including thermal boundary details, mechanical systems, ventilation systems, some appliances, renewable energy systems, and lighting fixtures. The HERS index rates each home on a scale where 0 is a zero-net-energy home and 100 is a home built to the 2006 base energy code. The current version of the Stretch Code requires a new house to be 70 and 65 if over 3,000 sq. ft.
This process begins during the design process; the HERS rater provides input on different options relating to insulation, air sealing tactics, mechanical ventilation, and basic info on mechanical systems. A typical HERS rating process for Stretch code compliance of a single-family home includes:
- A preliminary index (score) is submitted to the local building official during plan review. This is compiled using REM/Rate software and includes all relative designed features of the building.
- Before the drywall is installed, an air barrier inspection is done using an Energy Star checklist. Often diagnostic testing is done at the mid-point as well.
- After the building is completed and before the CO is issued, the energy model is adjusted with as-built conditions and the final HERS index is submitted to the building department.
A competent HERS rater will be a resource to the building team through the design and construction processes and will convey any opportunities to leverage utility rebates (upwards of $7k) to offset the cost of building a high-performance home.
HIS & HERS Energy Efficiency offers HERS ratings and rebate program support for builders and architects in Western Massachusetts.