An air-conditioned lobby can receive heat through sun-exposed glazing and humid outdoor air when the entrance opens. During rain, the same frontage must manage water at the frames, drainage outlets, and connections to the wall.
For buildings in hot and humid climates, glass and aluminum selection needs to address all three conditions. Solar control, air leakage, and rainwater management require different performance criteria and installation details. Specify the glass, framing, seals, and drainage together, taking into account the exposure and use of each opening.
Heat, Humid Air and Rain Affect Buildings in Different Ways
Solar radiation entering through glazing adds heat to the interior. Heat also transfers through glass and framing when indoor and outdoor temperatures differ. Coatings, IGU composition, and frame construction influence this thermal performance.
Outdoor air introduces a separate consideration: the moisture it carries. Leakage through joints and gaps, air exchange through open windows and entrances, and planned ventilation can all bring outside air into the building. The cooling and ventilation design needs to account for those conditions.
Rainwater can reach glazing channels, frame joints, and the connection to the surrounding wall. Seals, flashing, and drainage provisions need to work together to limit entry and direct collected water toward the exterior.
Reducing heat gain does not necessarily resolve indoor humidity. The Department of Energy’s research on humidity control in hot-humid homes explains why moisture loads can remain important even with more efficient windows and tighter envelopes. Establish the glazing requirements alongside the project’s ventilation and humidity-control requirements.
Choosing Low-E Glass and IGUs for Cooling Conditions
Low-E describes a coating, while an IGU describes the construction of a sealed glass unit. They can be combined in the same glass package, selected according to the opening’s solar exposure, thermal requirements, and intended appearance.
Select Solar Control According to the Opening
Low-E glass uses a low-emissivity coating to reduce radiative heat transfer. Depending on the coating, it can also limit solar heat gain while allowing daylight into the space.
For a hotel project in Miami, compare exposed glazing with openings sheltered by balconies or canopies. The solar-control specification should reflect orientation, shading, glass area, and how the rooms will be used.
Specify the solar heat gain coefficient (SHGC) for solar heat gain, U-factor for heat transfer, and visible transmittance for daylight, where applicable. State whether the values apply to the glass alone or the complete assembly. Together, these values define the selection more precisely than “Low-E” by itself.
Confirm the Low-E coating type, its position in the glass makeup, and fabrication requirements with the supplier.
Specify the IGU and Its Glazing Details
Insulated glass units combine two or more panes separated by a sealed space. Coatings, cavity construction, gas fill where specified, and edge components contribute to the unit’s thermal performance.
A residence in Florida might combine large fixed panes with smaller operable windows. Provide the dimensions and proposed glass makeup for each window type so the supplier can confirm overall IGU thickness, glass weight, and compatibility with the selected frame. Include safety and impact requirements where applicable.
IGU edge seals, sash seals, and perimeter joints serve different functions. Edge seals enclose the cavity between panes, sash seals work around moving panels, and perimeter joints form part of the frame-to-wall connection. Confirm the compatibility of glazing materials that contact the IGU edge seals with the supplier.
Controlling Air Leakage While Preserving Drainage
An opening connects to both the building’s air barrier and its water-management layers. Installation details need to show where the air seal is formed and how water can drain to the exterior.
Review Operable Seals and Perimeter Connections
Uncontrolled air leakage can carry humid outdoor air into cooled spaces or construction cavities. Condensation can occur if that air reaches surfaces below its dew point. The risk depends on the indoor and outdoor conditions and the path the air takes.
Check seals around moving sashes, joints within the frame, and connections between the frame and wall. Assess the product and its perimeter installation separately. Published product air-leakage data describe the tested assembly; the connection to the wall needs its own installation review.
For a renovation in New Orleans, establish whether existing frames will remain. Assess retained joints and show how the replacement work connects to the wall’s air barrier, including any concealed conditions that must be investigated.
Control unintended leakage while providing the ventilation required by the building design. Define the ventilation approach with the project team, including the intended use of operable windows.
Give Rainwater a Defined Route Out
Some glazing and framing systems collect water in channels and direct it toward exterior outlets. Keep the drainage routes required by the manufacturer’s design clear. Additional sealant should follow the installation details so it does not block those routes.
The Building America Solution Center’s guidance on window and door flashing cautions against sealing window weep holes, which allow water within the frame to drain out.
For an exposed opening on a Gulf Coast project in Louisiana, show how the sill, perimeter joints, flashing, and wall drainage layer connect. Make the designed drainage outlets accessible for inspection and cleaning after installation.
Selecting Windows, Storefronts and Curtain Walls
Fixed windows, operable windows, and commercial entrances have different requirements for airflow, maintenance, and everyday use. Select the system for the application, then match the proposed glass, framing, and installation details to the project’s performance criteria.
Max Windows: Plan for Ventilation and Closed-Window Performance
PRL Max Windows offers fixed, awning, and casement configurations with thermally broken aluminum framing. Fixed units provide views and daylight without an operable sash; awning and casement units add ventilation options and operating hardware.
For a residential project in Charleston, decide where ventilation is needed and how occupants will use the windows during warm, humid weather. Opening them can introduce outdoor air and moisture, so plan their use alongside air-conditioning operation and rain exposure.
Allow access to sash seals, hardware, and drainage openings for maintenance. PRL states that performance results vary by window type, dimensions, and glass configuration; use documentation applicable to the proposed unit.
Storefront: Review the Entrance and Surrounding Glazing Together
PRL storefront systems combine aluminum framing with compatible glazing and entrance components. Specify the glass makeup and thermal configuration of the selected framing, together with the perimeter installation details.
A retail project in Atlanta may combine fixed display glazing with a frequently used entrance. During warm, humid weather, repeated opening can increase outdoor air exchange even when the seals perform as intended with the door closed.
Review closing and latching, seal contact, thresholds, and adjoining storefront details. The entrance’s frequency of use should be considered alongside the assembly’s thermal, air, and water performance.
Curtain Wall: Review Facade Joints and Connections
PRL curtain wall systems provide options where standard storefront cannot meet the project’s size and load requirements. The selected framing, glass composition, joints, and anchorage need to suit the proposed elevation.
Detail drainage provisions and transitions to surrounding walls, roofs, or other facade systems. Assign responsibility for these connections before fabrication so adjoining work can be coordinated.
Review thermal, air, and water performance using documentation for the proposed assembly. Changes to glass makeup, dimensions, or framing may require a review of the relevant reports before approval.
What to Confirm Before Requesting a Project Quote
A quote request should describe the exposure, intended operation, and required performance of the opening. Provide the following information when available:
- Location and building use: Project address, application, and whether the space is air-conditioned.
- Dimensions and system type: Opening sizes, quantities, and window, storefront, or curtain wall configuration.
- Exposure: Orientation, shading, and exposure to rain.
- Operation: Fixed or operable windows, entrance use, and the intended ventilation approach.
- Glass makeup: IGU thickness, pane thicknesses, Low-E coating, and safety requirements.
- Performance criteria: Thermal, air, water, and structural requirements, plus impact requirements where applicable.
- Installation conditions: Wall construction, perimeter connections, replacement scope, and available drawings.
- Indoor conditions: Design temperature and humidity criteria supplied by the project team, where relevant.
Identify selections that remain open so they can be discussed before fabrication. This allows the supplier to evaluate available configurations against the stated requirements.
Planning a project in a hot and humid region? Contact PRL with your opening dimensions, proposed glass makeup, exposure conditions, system type, and performance requirements to discuss glass and aluminum options.
