Design Phase—System Integration

During the design phase, performance considerations are studied in context of how an innovation interacts with the other systems around it and with the building as a whole. Innovations can be optimally designed into a system that maximizes the performance of that innovation. When you are considering use of an innovation, three basic levels of rigor can be applied during the design phase.

At the high-level review, you would use software to analyze how the entire building would function from a building science perspective and how that function would change with the addition of an innovation. If the desired attribute of the innovation is energy efficiency, a whole building energy simulation would show the energy saved by that innovation in context with the rest of the building. If hurricane resistance was the desired attribute, a performance calculation of wind load resistance of the entire system including the innovation would show if the product helped reach the desired level of performance. These procedures are complex and would likely require specialized staff or outside professionals to complete. These procedures should definitely be used when building new construction.

Many projects will probably fall into the medium-level review. This review includes a step-by-step analysis considering how to optimally use the innovation, but without a whole building modeling. A standardized set of questions at this level will help ensure that all important issues are considered. An example of this assessment might be considering changing from a wood to a steel framed wall to increase structural integrity, but in considering other effects, you discover the need to add insulation to reduce heat loss across the more conductive framing material.

A low-level review would simply be considering the technology as a stand-alone system and optimally using that innovation without consideration for other systems. An example in which this level of review might be appropriate would be changing appliances (such as a dishwasher or refrigerator) and considering the performance characteristics (such as efficiency and durability) in selecting the item, but not taking the analysis any further. In this example, the low-level analysis is probably appropriate, given the limited effect these systems would have on other systems in the home or building.

Project Example: New Construction

You are planning to develop a new site, the first phase of which will be 12 two-family town homes. The architect suggests that you consider a particular type of spray foam insulation for the exterior walls and that you also use the spray foam in the rafters to create an unvented attic. What considerations should you take into account and where should you go to find reliable information regarding performance?

1. Identify the characteristics you are looking for in an insulation product. Lay out the attributes that you must have and those that you would like to have, but might be willing to compromise on. For example:
2. Review manufacturer’s literature and claims.
3. Perform Internet search for product applications and for unvented attics.
4. Has the product undergone any testing by recognized outside third parties?
5. Has the product been locally installed? Are there local examples of unvented attics?
6. Who are the local installers of the product? What are their qualifications?
   
   • Length of time in business.
   • References.
   • Certifications, training in product installation.
7. Is the product recognized/acceptable to the local code official?
8. What are the cost implications of using this product versus the lowest cost option?
9. Does using the sprayfoam obtain additional benefits versus a conventional, lower cost option?

Examples:

Offers added structural integrity to wall and roof system.
Air sealing function is integral to insulating function.