Those folks who have installed Radiant Barrier Insulation in the past few years know how effective it is at keeping Hawaii’s Solar Heat out of the home. (For those that aren’t up-to-speed, see the SolarGuard section of IslandCooling.com).
Until recently, Hawaii’s Energy code didn’t have provisions for this easy-to-install way to keep the heat out, leaving people stuck. Fortunately, the good people at DBEDT have come through with a revision that specifies how Radiant Barrier can be used to cool the home. They also included provisions for more natural ventilation in attics which makes it easier to retrofit Whole House Fans.
Look for Whole House Fans and other natural ventilation technologies to be available in future revisions of the Energy Code.
Below is an from the Energy Code Technical Seminar in November.
–Al Whitworth, Island Cooling
402.1.6 Ceiling insulation alternatives.
Insulation requirements for ceilings of buildings are permitted to be modified in accordance with Sections 402.1.6.1 through 402.1.6.8.1 for buildings:
1. Located in climate zone 1, and
2. Located at elevations below 2,400-foot (731.5 m).
402.1.6.8.1 Radiant barrier credit. To qualify for the radiant barrier credit (RB) described in Section 402.1.6.8, the installation of the radiant barrier must meet the following criteria:
1. The emissivity of the radiant barrier must be 0.10 or less. The manufacturer must provide test data or documentation of the emissivity as tested in accordance with ASTM E-408.
2. The radiant barrier must be securely installed in a permanent manner using one of the following installation methods:
For attic installations only, the radiant barrier shall be stapled or otherwise secured to the bottom surface of the top cord of the truss and draped below with the shiny side facing down.A minimum air space of ¾ inch above and below is required.
3. At least one square foot of free area for ventilation shall be provided per 150 square feet of attic floor area, or in the case of vaulted or open-beam ceilings, per 150 square feet of ceiling area.
Solar Guard complies with the above Radiant Barrier Specifications, and the installation description is consistant with the installation instructions for Solar Guard.