Energy-Efficient Building in a Hot Climate

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Fox Blocks ICFs provide a superior energy-efficient wall system for hot climates. Fox Blocks furnish continuous insulation (CI) and high thermal mass, both of which contribute towards a tight building envelope - a vital component for hot climate building design.

As temperatures in the United States continue to increase, today's commercial building owners demand energy-efficient buildings, both for the environment and to maintain their profits. Energy-efficient buildings save money, improve occupancy rates, and increase rents and market value compared to less green buildings. Therefore, architects and contractors in hot climates must design and construct energy-efficient buildings.

A Guide for Designing Energy-Efficient Building in a Hot Climate

The design of an energy-efficient building in hot climates must control air and moisture infiltration and reduce heat gains. To stop air and moisture infiltration, the design of the building must include a tight building envelope. Furthermore, architects and builders can reduce heat gains to a building’s interior through proper building orientation, shape and size, and window, door, and ductwork placement. In addition, an efficient landscaping plan can significantly reduce heat gains through both the wall system and glazings.

How to Create a Tight Building Envelope in Hot Climates

To stop thermal bridging and control moisture infiltration, the design of an energy-efficient building in hot climates must ensure a tight building envelope. The building envelope includes all the exterior parts of the building - the walls, roofing, foundation, windows, and doors. Two vital components of a tight building envelope include continuous insulation (CI) and energy-efficient facings and service openings.

Continuous insulation (as defined in ASHRAE Standard 90.1-2013) furnishes uncompressed and CI across all structural components without thermal bridges other than service openings and fasteners. The American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE 90.1) and the International Energy Conservation Code (2018 IECC) require CI.

When designing an energy-efficient building in hot climates, architects and builders must consider all the components of a building's envelope.

1. The Wall Design of an Energy-Efficient Building in Hot Climates

Designing energy-efficient buildings in hot climates require CI in the exterior wall. The application must follow ASHRAE 90.1 codes for the amount of CI required (as indicated by the R-value) according to climate zone locations.

Correctly applied CI hinders air and moisture infiltration and increases the effective R-value in a wall system. The higher the effective R-value of the wall system, the more it can resist thermal conduction. Thermal conduction occurs with warm particles spontaneously colliding with cooler particles. The design of energy-efficient walls in hot climates should furnish low-conductivity and high effective R-values.

Fox Blocks - An Ideal Wall System for Hot Climate Zones

The high thermal mass of Fox Blocks ICFs, with an R-value of 23, creates a tight building envelope for an energy-efficient building in hot climates. Fox Block ICFs offer a simple to install wall system that stops thermal bridging and the transfer of heat by conduction. Fox Blocks exceeds ASHRAE/ANSI 90.1 energy code requirements for all hot climate zones.

Furthermore, Fox Blocks' solid monolithic concrete wall, with a perm rating below 1.0, controls moisture intrusion into the wall system.

2. Cool Roof Design for Energy-Efficient Buildings in Hot Climates

Cool roof design in hot climates keeps a building and its attic space cool by reflecting and releasing the Sun's rays. Reflective roofing materials (such as tiles, clay, or slate), particularly those certified by ENERGY STAR, can provide significant cooling energy savings.

  • ENERGY STAR certified roofing materials decrease the transfer of heat to the building by lowering roof surface temperature up to 50F.
  • ENERGY STAR certified roofing products can lessen peak cooling needs by 10 to 15 percent.

In addition to the roofing product, the design of an energy-efficient roof in hot climates should provide wide overhangs, ideally three feet wide or more. Moreover, hipped roofs give shade to all sides of a building - a beneficial design feature in hot climates.

3. Foundation Design for Energy-Efficient Buildings in Hot Climates

A concrete slab foundation, along with a continuous layer of rigid foam insulation under the slab, can separate an energy-efficient building from the ground - an essential component of a tightly sealed building envelope. Without insulation, a significant amount of heat loss can occur, particularly around the edges of the foundation (80 percent). The addition of foundation insulation can result in energy savings of 13 percent. In hot climates, the design of an energy-efficient foundation must include insulation.

4. A Tight Building Envelope Must Include Energy-Efficient Facings

The design of a tight building envelope in a hot climate must include energy-efficient windows and doors suitable for the building's climate zone.

How to Design Buildings in Hot Climates to Reduce Heat Gains

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Builders and architects can design an energy-efficient building in hot climates to reduce heat gain through building orientation, shape and size, and window, door, and ductwork placement. In addition, an efficient landscaping plan can significantly limit heat gains.

1. Building Orientation of an Energy-Efficient Building

A building’s orientation tremendously affects the impact of the Sun and wind on the structure. Proper orientation can ensure comfortable living spaces through­out the year.

  • To lessen the building's solar exposure, orient its largest dimension north and south.

2. The Building's Size and Shape

  • Compact and straightforward exterior designs of a building can help save on energy by reducing the exposed surface. An open floor plan, along with outdoor spaces, can make a building appear and feel more substantial.
  • For buildings with southern exposure, the courtyard design helps to lessen the solar radiation impact on exterior walls by providing a cool, shaded area within the building.

3. Room Placement for an Energy-Efficient Building

In hot climates, room arrange­ment should consider the impact of the Sun's energy. For example, contractors should orient buildings north-south in the Northern Hemisphere. The north-south orientation minimizes direct sunlight during the summer (which lessens cooling demands) while limiting sunlight during the winter (which reduces heating requirements).

4. Window Placement for an Energy-Efficient Building

  • The windows of an energy-efficient building in hot climates provide both light and ventilation and should face north or south. Architects should avoid windows that face west and east because they can have much more solar heat gain than the north-facing windows, and more than that for the south-facing windows.
  • In hot climates, insulated shutters that can close during the hottest times of day can reduce energy loss.
  • The exterior design of an energy-efficient building should provide shade to all the windows.

5. Ductwork Placement for an Energy-Efficient Building

For an energy-efficient building in a hot climate, builders should locate the ductwork inside the building's envelope. Ducts placed in unconditioned areas can increase cooling costs by 15 percent. Furthermore, in hot and humid regions, moisture can collect on the overheated ductwork.

6. Landscaping for an Energy-Efficient Building in Hot Climates

Properly planned landscaping in hot climates can provide for energy savings by redirecting solar heat gains through roof overhangs, and shade structures around the building such as trees and shrubs. Also, since pavement reflects and radiates heat that it absorbs from the Sun, the landscape design of an energy-efficient building should shade all pavement near the building.


Please contact Fox Blocks ICF experts for more tips on how to design energy-efficient buildings in hot climates.