LEED Guidelines and Fenestration Design – Part 2

In the second half of this two-part blog (click here to read part one), we continue our look at how “smart” fenestration designs and applications can significantly improve a building’s performance using the guidelines in the LEED Rating System. This month we’ll take a look at Thermal Comfort, Daylighting and Views to the Outdoors.

Materials and Resources Credit 5: Regional Materials

Intent: To increase demand for building materials and products that are extracted and manufactured within the region, thereby supporting the use of indigenous resources and reducing the environmental impacts resulting from transportation.

Strategy:

Use building materials or products that have been extracted, harvested or recovered, as well as manufactured, within 500 miles of the project site for a minimum of 10 percent or 20 percent, based on cost, of the total materials value.

Note: Aluminum is manufactured from mined (extracted) bauxite. There are no bauxite mines in the United States. Therefore, regardless of where the manufacturer is located, aluminum framing systems do not qualify for this credit. LEED version 4.0, due out next year, will require manufacturers and their raw material suppliers to meet disclosure and responsible sourcing requirements.

This map above shows the world’s output of bauxite. The closest bauxite mines to the United States are in Jamaica.

Indoor Environmental Quality Credit 6.2: Controllability of Systems – Thermal Comfort

Intent: To provide a high level of thermal comfort system control by individual occupants or groups in multi-occupant spaces (e.g., classrooms or conference areas) and promote their productivity, comfort and wellbeing. Operable windows may be used in lieu of controls for occupants located 20 feet inside and 10 feet to either side of the operable part of a window.

Strategies:

• Design the building and systems with comfort controls to allow adjustments to suit individual needs or those of groups in shared spaces.

• Designs can include operable windows or hybrid systems integrating operable windows with mechanical systems.

The photo above shows Wausau Window and Wall Systems’ curtainwall system on the Omni San Diego Hotel with “zero sightline” vents as an integral part of the framing system. These windows appear to be fixed glazing when closed.

Indoor Environmental Quality – Daylight and Views

Credit 8.1: Provide daylight to 75 percent of regularly occupied spaces

Credit 8.2: Provide direct line of sight to the outdoors for building occupants in 90 percent of all regularly occupied areas

Intent: To provide building occupants with a connection between indoor spaces and the outdoors through the introduction of daylight and views into the regularly occupied areas of the building.

Strategies:

• Design the space to maximize daylighting and view opportunities.

• Daylighting strategies to consider include exterior sunshades, interior light shelves and high-performance glazing.

• Views strategies to consider include interior glazing partitions.

The photo above shows Tubelite’s Max/Block exterior sun shades installed on a storefront system. Note that the sun shades are installed about 2 feet below the top of the opening. This allows for natural daylight to be transmitted through the glass above the sun shades. Using an interior light shelf will help disperse daylight farther into the room and minimize glare near the windows.
This diagram shows sun angles for various times of the year in Nashville, Tenn.

Complying with LEED requirements does not have to be a daunting experience. It is important for all parties involved to know upfront if the project will pursue LEED certification. In some cases, the architectural aluminum manufacturer will need to know if there is a specific requirement for recycled content. Total system U-Factors and Solar Heat Gain Coefficients will need to be calculated to ensure that the thermal performance of the fenestration meets the design intent. Substituting products must be carefully reviewed – installing a different type of glass than what was specified may have adverse effects on the heating and cooling loads and daylighting.

The best way to determine if a project is following LEED guidelines is to review Division 1 of the specifications. AIA MasterSpec Section 01 81 13 Sustainable Design Requirements reads: “This Section includes general requirements and procedures for compliance with certain U.S. Green Building Council’s (USGBC) LEED prerequisites and credits needed for the Project to obtain LEED [Certified] [Silver] [Gold] [Platinum] certification. Other LEED prerequisites and credits needed to obtain LEED certification are dependent on material selections and may not be specifically identified as LEED requirements. Compliance with requirements needed to obtain LEED prerequisites and credits may be used as one criterion to evaluate substitution requests.”

 


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