High Performance Walls and SIPs

When building an energy efficient home, High Performance wall assemblies are critical components, and can be grouped into a couple of categories: 1. Built on-site advanced wall assemblies and 2. Prefabricated walls, to include SIPs.

Note that this blog post is largely dedicated to Polyurethane SIPs.  

ICFs, Insulated Concrete Forms, are a good option and are manufactured by several companies. Faswall and Nexcem have an interesting woodchip product. There are pros and cons for ICFs, and it is important to understand both.

Advanced Wall Assemblies

The goal is to improve the wall construction of conventional, stick built homes with advanced wall assemblies to include double stud, stagger stud or continuous insulation walls.

Double stud walls consist of two stud-framed walls set up next to each other to form an extra thick thermally broken wall cavity that can be filled with insulation. Because the interior and exterior framing are separated by insulation, thermal bridging is reduced or, ideally, eliminated.

Stagger stud walls use top and bottom plates that are normally 2×6 (5.5”) – 2×12 (11.25″).  Vertical 2 x 4 studs are then staggered alternately on each side of the plates. This is a good option for extra insulation, reduced thermal bridging and sound-proofing of spaces as well.

Another option is standard construction with a Continuous Insulation (CI) layer. In CI, builders add a continuous layer of insulation across the exterior of all structural members to reduce or eliminate thermal bridges, except for fasteners and service openings. Insulation is installed generally on the exterior of the building and is an integral part of the building envelope. Comfortboard 80 is an excellent vapor open product that can be used for a CI approach. Mineral Wool is generally favored, as foam tends to have low perm ratings and generally the desire is for our walls to dry to the outside.  Often folks using a CI approach do not use enough insulation to move the dew point outside of the wall assembly.  It is critical to have a vapor open approach if the dew point falls within the stud cavity.

Prefabricated Walls

Prefabricated walls are built in a factory, transported to the building site and craned into place. Manufacturers of these types of walls include:

Phoenix Haus, which designs and produces open sourced housing templates for walls that save energy, provide better insulation and allow homes to be more efficient with or without solar energy.

Build SMART simplifies the process of building a high-performance, energy-efficient structure with factory-manufactured modular components. Continuously insulated panels come with pre-installed, energy-efficient windows and doors and are delivered to the building site.

SIPs – Structural Insulated Panels. There are several types of SIPs out there. Generally, the difference between SIPs is the insulation.  Most are made with OSB (oriented strand board) skins, but some SIPs have different skins to include metal or MgO (Magnesium Oxide) skins. Most often, the insulation is EPS or Polyurethane.  However, there are some that are made with mineral wool, PolyIso (Polyisocyanurate) or XPS (extruded polystyrene).

Some SIPs are not considered structural (e.g. most metal SIPs), and they might be referred to as Sandwich Insulated Panels.

SIP panels made of EPS, XPS or PolyIso are glued together generally with Polyurethane adhesive. SIPs made with Polyurethane foam are adhered together with the foam itself creating a tremendous bond and a very strong wall panel solution.

Thermocore SIPS are made with polyurethane insulation core with interior and exterior skins of OSB. Panels are precisely and custom manufactured to the architectural drawings. Included in the SIPs are door and window bucks, headers, sub facia and electrical conduit boxes. Also, beam pockets and additional structure like 2x, LVL or steel posts can be built into the panels.

Construction with Thermocore SIPs is quicker than framed homes. The time from foundation to dried-in is significantly reduced. Labor costs are lower, which is ideal in places where available labor is scarce, costly, unreliable or poor quality. Thermocore SIPs are stronger than framed walls, with lower thermal bridging.

Thermocore SIPS often have higher material cost, the electrical requires pre-planning and can be considered less environmentally friendly due to foam, which is a petrochemical product.

The thermal performance values of SIPs and lower labor costs often make up for the initial cost and planning. SIPs help to achieve a more air tight building as well. In the Passive House and Zero Energy industry, where energy efficiency, comfort and clean air are the goals, Thermocore SIPs are an optional building solution.

For more information on SIPS, call us at 720-287-4290.

Sources: U.S. Department of Energy, Greenbuildingadvisor.com, Thermocore.com

High-Performance Windows

If eyes are the windows of the soul, then windows are the eyes of the energy-efficient home.

Generally, windows are the weak link in the walls of a home. “I love putting plastic on my windows to keep cold air out and warm air in,” said no one ever. That is why considering the brand and style of the windows in a home is just as important as deciding insulation and exterior materials.

The goal is comfort and operational cost saving, and the goal for builders and architects is providing both.

High performance windows are necessary in keeping with Passive Haus standards of efficiency: design, minimal thermal bridging, air tight, super insulated, optimized glazing, energy recovery ventilation and passive gains.

So we have learned that code built homes often lose 20 to 40% of the heat in the home through air infiltration, and windows and doors are a significant source of this heat loss.

To better grasp just how significant, imagine the volume of a basketball as our measure of air infiltration. According to the National Fenestration Ratings Council (NFRC), the maximum allowable air infiltration in a window, with the outside wind at 25 mph, is 0.3 CFM (cubic feet of air)/sq. ft. Air infiltration for a 10 sq. ft. standard window at the allowable maximum is 3.0 CFM or 11.4 basketballs per minute. At sixty minutes, one window allows in 684 basketballs per hour.

If you have (30) 10 sq. ft. windows, that equals 342 basketballs per minute or 20,520 basketballs per hour. That is a substantial amount of heat loss.

How do we reduce the basketballs?

Consider installing Alpen or Advantage Woodwork High-Performance windows. With a high-performance window, air infiltration at a 25 mph wind is <= 0.01 – 0.05 CFM (cubic feet of air). A 10 sq. ft. high performance window is at 0.10 CFM or .38 basketballs per minute or 22.8 basketballs per hour.

Therefore, (30) 10 sq. ft. windows equals 11.4 basketballs per minute or 684 basketballs per hour. We just went from 20,520 to 684 basketballs per hour. To summarize, that’s approximately a 97% reduction of air infiltration from what the NFRC says is acceptable.

The bad news is loss of air through a structure’s windows is like opening the windows and tossing our hard-earned money out of them. The good news is high performance windows fixes that problem.

The overall quality and performance of windows like Alpen or Advantage High-Performance windows is also superior. What makes these windows even more unique are their individual components, designed to combat heat losses (winter) and gains (summer):

  1. Frames – High performance windows have durable, low conductivity frames which generally include insulation. These frames offer better thermal performance. The R-value of most standard frames is r-2 to r-3.5. High performance window frames are r-4 and up to r-7, 8, and 9.
  2. Seals – High performance windows generally have multiple seals, which promote not only weather tight but also air tight seals.
  3. Glazing – IGUs (insulating glass units). Glazing can have double, triple and even quad glass. High performance IGUs have special coatings that high performance window manufacturers leverage to optimize heat gain from the sun in colder months and reduce heat gain and over-heating in the warmer months.
  4. Spacers – Depending on the material used, the spacers in between the IGUs can help increase the interior surface temperature of a window up to 15 degrees. For example, a galvanized steel spacer in a fixed high profile Alpen 525 window is rated R-5.9, whereas a stainless-steel spacer in a fixed high profile Alpen 625 window is R-6.7. Also, high performance window spacers reduce condensation on the edge of the glass (which reduces opportunity for mold and rot) and increases the inside glass surface temperatures, therefore improving comfort.
  5. Gas – There is “gas between the glass,” as it is denser than air and a reliable barrier to heat loss. Argon or Krypton gases are often used. Argon is much less costly, but Krypton increases performance and is often used in Passive House projects.

While ROI (return on investment) is important, comfort and unnecessary energy use are the primary reasons people pursue high performance windows.

High-Performance Windows help create high performance homes which conserve energy for future generations.  We are “burning” through our energy resources (coal and oil) rapidly.  Why not own a comfortable, energy efficient home that is also super quiet and will likely last much longer than your neighbor’s home?   And … let’s conserve our resources for future generations.

Please do not hesitate to call us at 720.287.4290 to learn more.