The sheet radiant barrier or interior radiation control coating (IRCC) options may be claimed where the radiant barrier system is to be installed in one of the configurations depicted in Figure R405.7.1, and the following conditions are met:
- It shall be fabricated over a ceiling insulated to a minimum of R-19 with conventional insulation and shall not be used as a means to achieve partial or whole compliance with a minimum attic insulation level of R-19. Either a sheet type or spray applied IRCC may be used.
- If the radiant barrier material has only one surface with high reflectivity or low emissivity it shall be facing downward toward the ceiling insulation.
- The attic airspace shall be vented in accordance with Section R806 of the Florida Building Code, Residential.
- The radiant barrier system shall conform to ASTM C 1313, Standard Specification for Sheet Radiant Barriers for Building Construction Applications, or ASTM C 1321, Standard Practice for Installation and Use of Interior Radiation Control Coating Systems (IRCCS) in Building Construction as appropriate for the type of radiant barrier to be installed. The operative surface shall have an emissivity not greater than 0.06 for sheet radiant barriers or 0.25 for interior radiation control coatings, as demonstrated by independent laboratory testing according to ASTM C 1371.
- The radiant barrier system (RBS) shall conform with ASTM C 1158, Use and Installation of Radiant Barrier Systems (RBS) in Building Constructions for Sheet Radiant Barriers, or ASTM C 1321, Standard Practice for Installation and Use of Interior Radiation Control Coating Systems (IRCCS) in Building Construction for IRCC systems.
- The radiant barrier shall be installed so as to cover gable ends without closing off any soffit, gable or roof ventilation.
ACCEPTABLE ATTIC RADIANT BARRIER CONFIGURATIONS
The cross ventilation option may be used if the following criteria have been met.
- Operable aperture areas totaling a minimum of 12 percent of the floor area of the room shall be provided for all primary living areas and main bedrooms.
- Insect screens shall be provided for all windows and doors to be considered operable aperture area. All screened entry doors and interior doors in the ventilated areas shall be provided with either (1) mechanically attached door stops (or similar devices) to hold the door in an open position or (2) operable louvers.
- The total aperture area shall be provided by a minimum of two distinct windows. Each window shall provide not more than 70 percent of the total aperture area. The windows (or sliding glass doors) shall be placed in adjacent or opposite walls. The windows may be placed on a single outside wall if wing walls are used.
- Where wing walls are included in the building design for ventilation purposes, they shall be placed between windows to create a high-pressure and a low-pressure zone on each window. Wing walls shall extend from the ground to eve height, be located on the windward side of the building, and extend outward from the building a distance at least equal to one-half the width of the window. NOTE: This technique is effective only for areas which experience significant and continuous winds during the cooling months.
The whole house fan option may be used if the following criteria have been met.
- The whole house fan has been sized to provide a minimum of 20 air changes per hour for the entire house.
- The fan installed shall have a free air cfm rating of at least three times the square footage of the conditioned area of the house.
- To ensure adequate air exhaust, the house attic shall have gable, ridge or wind turbine vents whose total opening area is equal to four times the ceiling cutout area for the whole house fan. Soffit vents shall not be included in the exhaust vent area.
The ceiling fan option shall apply a 2-percent reduction in cooling energy use for the proposed design if one or more ceiling fans are installed in each of the bedrooms and a minimum of one ceiling fan is installed in all primary living areas (living rooms, family rooms or great rooms). This shall not include spaces designed to be dining rooms or dining areas. Areas separated by permanently fixed archways, walls, or dividers shall be considered separate rooms. The following criteria shall be met:
- Ceiling fans shall be installed with minimum fan blade diameters of no less than those listed in Table R405.7.6 for the size and shape of the room.
- Where a primary living area is an "L-shaped" room and the smaller portion of this area is 8 feet by 10 feet (2438 mm by 3048 mm) or larger, a fan shall be installed in both the larger and smaller portions of the primary living area.
|LONGEST WALL LENGTH (feet)||MINIMUM FAN SIZE (inches)|
|> 12 — 16||48|
|> 16 — 17.5||52|
|> 17.5 — 25||56|
|> 25||2 fans (minimum of 48 inches each)|
The HRU option may be used for installation of a waste HRU on either an air conditioner or a heat pump where the HRU has a minimum net useful heat exchange effect of 50 percent and meets the following criteria:
- The net useful heat exchange effect shall be demonstrated by either a Form R400D-2014 prominently displayed on the unit with test results clearly visible for inspection or by an ARDM certified refrigerant desuperheater seal affixed to the unit.
- The net useful heat exchange effect shall have been determined by an independent laboratory testing to AHRI Standard 470.
- If more than one air conditioning system is installed in a residence and only one HRU is installed, energy load shall be based on the gallon capacity of the water heater to which it is coupled and the total capacity of the water heaters in the residence. In such case, the HRU shall be attached to the system serving the daytime primary living areas (family room, living room, kitchen, dining room and adjacent bedrooms and bathrooms).