Natural ventilation designs are more significantly affected by climate and weather than mechanical systems. Although the methodology and inputs for documenting compliance are the same as for mechanical systems, in certain regions project teams using passive systems may have difficulty meeting ASHRAE-55 due to program constraints or seasonal temperatures that are outside of the prescribed range of 50°F–92°F.
Don’t assume that projects in Southwestern or other dry climates will automatically meet the humidity requirements of ASHRAE-55. These climates may have a significant number of days in which operating conditions will exceed the ASHRAE-55 requirements for humidity. Refer to the National Climatic Data Center for regional weather data (see Resources).
In order to achieve IEQc7.2, you have to achieve IEQc7.1, and you will have to install a permanent monitoring system to provide ongoing feedback about thermal conditions. If you are only pursuing IEQc7.1, there is no requirement for a permanent monitoring system. Residential projects cannot earn IEQc7.2.
Consider design implications of credit requirements early in program development. For example, if you are in a humid climate you may need additional dehumidification, which will affect your mechanical space requirements.
Base building mechanical systems have to allow for the tenant fit-out to meet the requirements of ASHRAE-55. If all the mechanical systems are relegated to tenant fit-out, core-and-shell projects are not eligible. Consider this early in the planning phase of a LEED-CS project.
If the LEED performance period is less than one year, extrapolate costs based on historical trends so that they represent the best estimate of annualized performance period costs.
Become familiar with the required data and begin tracking cost impacts early in the LEED process. It is much easier to document costs as you go than to investigate costs retroactively.
Work closely with the accounting division of your organization to identify this information. For buildings with relatively detailed records and a willing accounting department, this credit should be very achievable.
Most buildings have this data in some form, but project teams need to compile reliable figures and categorize costs accurately to provide the documentation required by LEED.
