| -- End Ad Box ---> | | | | pouring and/or injecting loose foam beads or liquid |
| When we talk about energy efficiency, we first have | | | | foam. Some manufacturers make concrete blocks |
| to understand some basic definitions Energy | | | | that accommodate rigid foam inserts. |
| efficiency of building materials is determined by how | | | | Stud Wall Construction using wood or metal studs ... |
| it handles heat, how heat transfers through materials | | | | The exterior wall constitutes a large part of the total |
| and how well materials hold or store heat. | | | | insulated package. In exterior walls, a 2x6 wall offers |
| Remember, heat always moves from warm to cold, | | | | upto 5.5" of insulation. With the use of 2x6 studs |
| so during the summer, if the outside temperature is | | | | spaced a 24" c/c , not only is the depth of the wall |
| warmer than the inside temperature of a home, heat | | | | cavity increased but the width of the cavity is also |
| transfers through the walls from the outside in. | | | | increased. Studs conduct more heat than the |
| Conversely during winter, if the inside air temperature | | | | insulation since it extends through the wall cavity and |
| is warmer than the outside, heat transfers from | | | | has a smaller R-value. So, in 2x6 construction there |
| inside the home out. | | | | are fewer studs in the exterior wall and less heat is |
| Clear Wall R-Values | | | | conducted through the wall. The following website |
| Clear-wall R-Value calculations do not take into | | | | has a good table describing R-Values of various |
| consideration the effects of additional construction | | | | stud-construction methods |
| like windows, doors, exterior wall corners and how | | | | Insulating Concrete Form (ICF) Construction ICF uses |
| the roof joins the walls. When factored in, R-Values | | | | reinforced concrete as structure and where insulation |
| typically drop from those stated as Clear-wall | | | | does double duty also as permanent stay-in-place |
| R-Values. Clear-wall R-Values and their thermal | | | | formwork for concrete during placement is a very |
| performance are determined by testing a solid wall | | | | attractive choice for walls of energy efficient |
| (complete with its insulation system), usually a section | | | | buildings. The insulating material, typically expanded |
| 8 ft. x 8 ft., with no openings for doors and windows. | | | | polystyrene (EPS) affords a variety of |
| Whole Wall R-Values | | | | state-of-the-art exterior finishes, such as siding, brick, |
| Clearly more accurate is the Whole-wall R-Value | | | | cultured stone, stucco, and so on. Constructed from |
| rating system. In this system, not only is the thermal | | | | expanded polystyrene and stacked like building blocks |
| performance of the wall tested, so is the typical | | | | to form the exterior walls of a home, the forms are |
| envelope interface details. These include wall-to-wall | | | | reinforced with steel and filled with concrete. The |
| corners, wall-to-roof, wall-to-floor, wall-to-doors and | | | | forms interlock and fasten one to the other to |
| wall-to-window connections. Why include these | | | | provide seamless "foundation to rafter" fully insulated, |
| details? Because energy efficiency is lost at these | | | | reinforced concrete walls. Window and door openings |
| points of construction and including these elements | | | | of any size are possible. Because of the triple |
| provides a more accurate R-Value rating system. | | | | insulative nature of these forms, ICFs are extremely |
| (Although taking the time to tape these joints during | | | | energy efficient. The R-value of the insulation, |
| the construction helps reduce some of hte heat loss | | | | coupled with the thermal mass of the concrete, and |
| significantly.) | | | | the elimination of air leakage, makes for an R-40 |
| Thermal Mass | | | | energy rating or higher. |
| To add to the confusion we have to consider | | | | Structural Insulated Panels (SIP) SIPsconsist of two |
| thermal mass, perhaps the most confusing energy | | | | outer skins and an inner insulation core. Most |
| issue facing engineers, contractors and homebuyers | | | | structural panels today use either plywood or |
| today. Thermal mass ratings are determined by | | | | oriented strand board (OSB) as skins. OSB is most |
| measuring the building materials/wall unit energy | | | | commoly used because it is available in large size upto |
| efficiency in conjunction with other layers of | | | | 12 ft by 36 ft. Expanded polystyrene (EPS) is the |
| materials attached to the wall, i.e.; particle boards, | | | | most commonly used insulation core material. |
| drywall, stucco. The measurement of the energy | | | | Extruded polystyrene (XPS) commonly known as |
| performance of a "stated R-value" material, combined | | | | styrofoam, polyurethane foam and isocyanurate are |
| with the layering of other materials to enhance the | | | | also used as the inner core but predominantly EPS is |
| energy value, is often referred to as "mass-enhanced | | | | the used as the inner core. As you can see in the |
| R-value." There are a number of combinations of | | | | table below, EPS has an R-value of 5.00 per inch. |
| materials used in construction and their thermal mass | | | | Many SIP manufacturers allow you to select the |
| and R-value efficiencies vary depending on how they | | | | thickness of the panels for your home ranging from |
| are used in the region of the country (climate | | | | 4" to 12". SIPs are becoming increasingly common in |
| considerations). How efficient a system is and how | | | | modular home building as they have shown extreme |
| much energy consumption is reduced depends on | | | | energy efficiency, are much stronger than |
| how fast heat transfers through materials, how well | | | | wood-framed homes and the outer envelope can |
| materials hold the heat and the fluctuation of outside | | | | often be constructed in under one week! If you are |
| temperature. Attention to details like the windows | | | | a contractor or engineer who wants more |
| you select, like low e-thermal, dual pane windows | | | | information about SIP's see Some manufacturers |
| that are tinted, is just as important as the R-value in | | | | choose to use polyurethane and isocyanurate as the |
| the walls. In fact, much heat loss or gain, up to 48%, | | | | insulating material. Aged polyurethane and |
| is through windows, not walls! | | | | isocyanurate SIPs have a nominal R-value of around |
| Additionally, according to the US Department of | | | | R-6 to R-7 per inch (2.5 cm) of thickness. |
| Energy, for energy efficiency, your home should be | | | | Polyurethane/isocyanurate panels, although more |
| properly insulated from the roof down to its | | | | expensive, are more fire and water vapor-diffusion |
| foundation. This includes the following areas: | | | | resistant than EPS, and insulates some 30% to 40% |
| Attic spaces | | | | better than EPS or XPS, per given thickness. |
| Attic access doors to unfinished attics | | | | Precast Concrete Wall Construction ... Precast |
| Knee walls in finished attics | | | | concrete walls use use high-strength concrete, |
| Ducts in unconditioned spaces | | | | typically 5,000 psi with reinforcing steel and fibers. |
| Cathedral ceilings | | | | Priced in the $55 - $65 range per linear foot of wall, |
| Exterior walls | | | | precast systems are competitive with other |
| Floors above unheated garages | | | | foundation walls, particularly when costs are |
| Foundations | | | | examined as an assembly that includes footings and |
| Basements | | | | sub-slab drainage. The precast concrete walls have |
| Crawl spaces | | | | full-length insulation built in to increase energy |
| Slab-on-grade floors. | | | | efficiency. They are smart, with convenient features |
| Let us look at some of the current choices in | | | | like built-in accesses for wiring and treated wood |
| construction of today ... | | | | nailers for drywall. The walls have a built in footing to |
| Block Masonry and Poured-Concrete for residential | | | | be placed on a base of stone. The average R-Rating |
| construction There are numerous insulation methods | | | | I found doing a search was about 12.5. |
| and new insulated block systems on the market with | | | | Overall, there are a lot of choices you have to |
| varying R-values. Standard 8" hollow block's R-value is | | | | make...Do you want to spend more money at the |
| 1.75, which by itself, is not enough R-value to achieve | | | | front end to make an energy efficient home, or foot |
| energy efficiency. The addition of outside insulation, | | | | the increasing power bills. Many of the new |
| integral insulation or interior insulation can be added to | | | | construction methods dramatically improve the speed |
| standard block to make it very energy efficient. | | | | at which homes can be built. Discuss these options |
| There are several ways to incorporate foam | | | | with your contractor and or engineer to find out |
| insulation—such as polystyrene, polyisocyanurate or | | | | what is best for your specific purpose and area |
| polyiso, and polyurethane—into concrete blocks. The | | | | where you live. |
| hollow cores of concrete blocks can be filled by | | | | |