Team Project Paper #1 Energy and lighting

Bud Munson

This project is the Artesia Springs Residential development project in Bend.  As mentioned in my class briefing it is an eight lot development project in Bend.  The land is 1.58 acres and is located in NE Bend.  The project has existing residential development on three sides and a canal I the east edge of the site.   The site is inside the city limits and is located near schools and shopping and is in a transit line.  The site will be developed flat, and as many tress that can be left onsite will be.  The Mission statement of the project is “To bring sustainable building and affordable building together in one project for the purpose of making this technology accessible to as many people as possible.  Sustainability must come down from the category of high end, custom homes, to a place where it becomes the norm in production building”.  Our basic goal here is to build a median priced production home that is at least 50% more efficient than a  standard stick built “code” home for only 10% additional cost.

The Purpose of this paper is to analyze the differences in performance and cost of the available technologies for creating a building envelope in a residential building environment.

The technologies that we will be comparing here will be standard bat insulation, blown in blanket insulation, blown in foam insulation, staggered stud framing with all three types of insulation, structural insulated panels (SIP’s) and insulating concrete forms (ICF).  Our goal will be to determine the technology that will give us the best insulation factor at the least expensive price.  We are probably not going to be looking for the most effective means of insulating a home.  But rather, the most cost effective.  The first technology will discuss is “Insulated Concrete Forms”.

The Insulated Concrete Form Association states in its website that: “This combination of high R-values, low air infiltration, and high thermal mass is believed to account for a 25% to 50% energy savings of ICF versus wood or steel-framed homes.”

I have had some limited experience with building an ICF building.  In a home that we built in 2006 we determined that the additional cost of the ICF envelope, including all the extra costs associated with installing system itself, cost approximately 20% to25% more than it would have to do standard 2X6 exterior framing with bat insulation.   Although this analysis will show that this technology is probably the most effective system for making a structure more efficient it is also the most expensive.  If concrete prices came down, if the system technology costs came down and the building trades improved their techniques for applying this technology I believe it could become a very viable system in the future.  But, for now, it is simply too expensive and does not allow us to achieve our stated goal.

In this section I am going to lump together standard bat insulation, blown in blanket insulation and blown in foam insulation.  I think obviously the standard 2x6 exterior framing with R-21 bat insulation is the least expensive and the least efficient system that you can put in.  It is, or at least has been the industry standard for a very long time and standard building codes are typically based on this system.  This standard was created and used because in the past cheap available energy sources made it the most viable and cost effective system for a building envelope.  But, as we all know, the increased cost and increased demand for energy is slowly making this less efficient technology less and less attractive. The R-21 is reduced to closer to R-17 or R-18 with the use of standard framing techniques. It is certainly the least expensive but also the least efficient system and so we don’t see it as the best system to be used.  It is in fact at this time the standard system and as such is the baseline that we are trying to improve upon.

Using standard 2X6 exterior framing but adding to it a blown in blanket insulation or a blown in foam insulation improves the efficiency of the standard system from approximately R-18 to about R-23 for blown in blanket insulation and about R-24 for the blown in foam insulation.  This is definitely better than standard but also more expensive.  The insulating contractors will up-charge for the cellulose blanket insulation or the sprayed foam insulation partly for the additional cost of the materials and partly for the increased cost of installation.  Although these systems offer higher R-values and less air infiltration then standard bat insulation, the increase is not that great.  If this were all you had it would be cost effective and would offer higher than standard efficiency and would be recommended, but, we are looking for the best “bang for the buck”.

If you were to combine any of these three systems to a staggered stud framing profile it would improve them even more and would be pretty close to what we are going to recommend here.  With staggered stud framing you get a better R-value because of the reduced area of surface exposure of the wood or metal framing.  With any of these forms of insulating the efficiency of the system is reduced by the exposure of the framing to the inner and outer surfaces.  By staggering the studs and placing insulation over the stud, the area of the stud that is exposed to surface area is reduced and the efficiency of the insulation is improved.  We believe that this is preferable to standard framing, but is less accepted in the building trades and you will usually get an up charge from your framing subcontractor for this type of framing.

Comparing blown in blanket insulation and blown in foam insulation with standard and staggered stud framing you find that as the efficiency gets higher, so does the cost of the insulation, the application and the basic labor costs associated with each type.  Of all these systems, blown in foam insulation with a staggered stud framing configuration is probably the most efficient system but it is also the most expensive.  If this was the only improved system you had available to you, it would be a good way to go.

This brings me to the only system we have not yet discussed and the one that we feel offers the most efficiency at the most competitive cost.  In the last few years several companies around the country have begun to offer a product called Structural insulated panels, or (SIP’s) as they are referred to in the trades.  SIP’s, are a modular system of exterior walls, roof and floor that are designed and built specifically for each home.  A builder takes the plans for the home to the SIP’s manufacturer and they do a take off and provide the builder with a cost estimate for doing the exterior walls, the roof panels and a flooring system as a factory built and site delivered and installed system.   They will break down each category so the contractor can compare the costs to a standard system.

The manufacturer uses the plans to create a complete envelope for the entire home.  That envelope is designed and built at the factory under very precise specifications and quality control.  The system is then delivered to the job site and installed by the framing contractor.  The use of an overall system of walls, roof and floors takes advantage of a “pre-fab” design to provide a very efficient product that is easy to install.  The reduced installation costs, the higher R-values and the low air infiltration qualities of this system make us feel that this is the most cost effective and efficient system at this time. 

The design of a SIP’s panel is such that the structural rigidity needed for walls, roof and floor systems is achieved without having studs every 12” to 24” thus improving the R-value of the rigid foam insulation used in the panel.  Standard OSB material is used to sandwich the rigid foam material into a modular panel. A very high R-value and a very low level of air infiltration are achieved.  These two factors combined with a very structured high quality production environment create a very efficient and cost effective building envelope system.  Currently manufactures claim and the Structural Insulated Panel Association “SIPA” believe that a 40% to 60% improvement in efficiency can be archived using a SIP’s envelope system.

I would like to devote one small paragraph here to lighting.  The lighting possibilities are varied, the least expensive option is to replace as many bulbs in standard lighting configurations as possible with CFL bulbs and achieve a minor level of improvement.  Some areas may allow some newer my efficient lighting systems but the technologies are still developing and thus can require a significant increase in cost.

Our stated goal of a 50% increase in efficiency can nearly be achieved using a SIP’s envelope alone.  But by adding more efficient windows and doors, reducing the size and increasing the efficiency of the HVAC system, specifying more efficient appliances and possibly a solar thermal hot water heating system we can easily achieve our efficiency goals.  By using some of the incentive programs available we can add these various efficiencies until we get to our stated goal of a 10% increase in cost.  One other system that we think could really be worth the additional cost, but likely will exceed our 10% cost increase goal is under floor radiant heating tied with the solar thermal hot water heating system.  I believe we can achieve the goal of the median priced home but the 10% increased cost parameter would likely be exceeded.  So we could provide it as an option.