Energy Savings

 

Energy consultant Mark Whitaker of Mesquite, Texas compared various thermal envelopes (SIP, stick framed, concrete, etc.) and projected the utility costs one could expect to pay, based on the type of HVAC system, local utility rates, and heating and cooling days.

 

The results at right compare the operating costs of a 1,522 square foot home in Dallas, Texas, using two different thermal envelopes - SIPs (green) versus traditional Stick (brown).

 

Based on these results, the following energy savings can be realized over the periods shown:

 

5 YEARS

$3,183

10 YEARS

$6,089

15 YEARS

$8,631

20 YEARS

$10,697

Estimated operating costs @ 4% annual cost Increase

Heating and cooling is typically the largest home expense after the mortgage payments. Building with SIPs can help you meet the performance guidelines of an ENERGY STAR new home.  The R-Value of a typical SIP wall is R-25. The lifecycle costs of building with SIPs are unmatched.

 

"The Florida Solar Energy Center (FSEC) found a 12% to 17% energy savings from using SIP construction. The FSEC also monitored side-by-side SIP and conventional wood-framed structures for several winter months. The airtightness of the SIP house (measured at 0.21 air changes per hour [ach]) and was better than the conventional wood-framed house (measured at 0.27 ach)."

- U.S. Department of Energy's website on Energy Efficiency and Renewable Energy

Structural Insulated Panels are completely compliant with international building codes, and provide a structure inherently stronger and more suited to withstand natural disasters.

 

"An increasing number of houses are being built with SIPs. They are attractive because of their relatively high-uniform R-values, square, flat and plumb walls, and ease and speed of construction. Problems with natural pests can be minimized with adequate prevention measures. Buildings made of SIPs appear to be safer than some other types, even in fire."

- U.S. Department of Energy's website on Energy Efficiency and Renewable Energy

The Inconsistency of R-Values

"Although R-values are a convenient and common yardstick to measure thermal performance, the usefulness of them is limited. In a 2000 study by Brock University in Ontario, two almost identical homes - one built with stick frame and the other with SIPS - were compared for energy efficiency. Thermal analysis revealed the 2-by-6 stick-frame house (rated at R-20) actually performed at an R-4 equivalent while the 4 1/2-inch-wide SIPs home performed at a true R-17 level in 13-degree temperatures. The reason for the wide discrepancy is because, unlike frame systems, SIPs offer continuous insulation values across large areas of airtight walls, unbroken by studs that would otherwise conduct hear and let cool air into the building. In terms of real-world energy conservation, the SIPs home consumed only a quarter as much energy over one year as its stick-built counterpart, even though R-value ratings were comparable."

Mother Earth News - October/November 2005

SIPs vs. Concrete Masonry Units (CMUs) - R-VALUES

Calculated R-Values are for generic Structural Insulated Panels and include 2 sheets of Fiber Cement at .69 per side, plus Type 1 EPS foam that meets ASTM C-578, calculated per ASHRAE published values at 0.006/in at 75°F, 0.0065/in at 95°F, and 0.0067/in at 113°F. Values vary on panels due to the nature of foam core. Values do not vary on CMUs.

 

R-Value is a means of measuring a structures ability to resist heat transfer. Typical 4” lightweight CMU hollow core walls have a calculated R-Value of 2.41 uninsulated, and 4.43 insulated with Perlite Cavity Fill. The 6” thick wall exhibits a 2.64 uninsulated, and 6.75 insulated with Perlite Cavity Fill. Fiber Cement SIP walls exhibit more than 3 times the R-Value of typical insulated CMU walls of the same thickness.


INTERIOR SURFACE TEMPERATURE - Thermal Lag

Masonry homes work on the principal of thermal mass. The masonry product does not have an R-value but does delay the heat transfer through the walls. Thus, interior wall temperature may rise steadily through the daytime, peaking 5 hours later in the evening. In most concrete block buildings, the max heat reaches the inside about 7 p.m. and continues until 10 p.m., often not recovering to the original low temperature.

 

SIP walls resist heat transfer, and thus the interior wall temperature remains fairly constant throughout the day.

 

“Heating and cooling load studies have found that heat transmission through walls is the greatest factor in energy loss in buildings, 8% greater than the heat transfer through windows, and 39% greater than transmission through roofs.” - Jan Kosny, PhD., R-Value Misconceptions

 

SIP walls are superior to conventional walls in a number of ways. SIPs combine a high insulation R-value with speed and ease of construction.  

 

 

Share on Facebook

GLOBAL BUILDING SOLUTIONS • 2509 CLEMENTS FERRY ROAD • CHARLESTON • SOUTH CAROLINA • 29492 • 843-270-0733 • INFO@GLOBALBUILDING.NET