855773644-LEED-v5-BD-C-Reference-Guide-Launch-Edition - Page 528

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space assuming 400 people will be in that 20,000 square feet area (1,858 square meters).

A 20,000 square feet (1,858 square meters) zone can accommodate up to 1,000 people. Therefore, the project would meet the sizing requirements.

Thermal habitability Define habitable conditions as applicable to the project type. Thermally safe conditions may differ from a healthcare facility to a typical office building. For example, the heat stress index for an office building will be different than a nursing home. Consider the project type and the population when performing the initial analysis. Thermal habitability is not thermal comfort and will therefore be different than the comfort zone prescribed in ASHRAE Standard 55 .

Natural ventilation Thermal safety zones must have access to natural ventilation. This is achievable through operable windows, doors, operable panels, or louvers.

Thermal models Thermal models analyze heat transfer within a building, accounting for climate, insulation, glazing specifications, solar gains, envelope leakage rates, and ventilation. Use computer simulation software to perform the thermal modeling for each path, based on project-specific inputs. Consider using modeling tools that are approved for Passive House compliance.

The analysis uses a two-day period. This was selected as an entry-level duration for LEED projects for design purposes. A four-day period has been used previously in the LEED v4 pilot credit Passive Survivability and Back-up Power During Disruptions. A timeframe of 72 hours (3 days) is often used for general emergency preparedness planning (such as disaster-ready kits). For example, extreme heat or cold periods can last longer than two days. According to the EPA using heat wave tracking data by the National Oceanic and Atmospheric Administration (NOAA), the average heat wave in major U.S. urban areas has been about four days long. [190]

PATH 1. CONSIDER EXTREME HEAT

Demonstrate with a thermal model that the building will passively maintain habitable conditions for at least two days during a power outage in hot, summer months. The two-day period must represent the peak summertime conditions of a typical meteorological year (TMY).

AND/OR

190 https://www.epa.gov/climate-indicators/climate-change-indicators-heat-waves#ref6.

U.S. Green Building Council LEED v5 Reference Guide for Building Design and Construction, April 2025 Launch Edition 518