Climate analysis

Climate analysis during pre-design helps provide an understanding of how the local weather conditions will impact the building's design and performance. In particular, it helps to provide an understanding of factors that may impact the occupants' thermal comfort, and also inform which passive design strategies may be used. This may influence design concepts employed by the architectural designer during the conceptual design phase.

This page provides an overview of how a climate analysis is performed. Links to additional detailed tutorials are included for more detailed guidance.

Analysis objectives

Some concepts to explore in an early stage climate analysis include:

• When is the weather "comfortable?" Do operable windows make sense for this project?
• Availability and intensity of solar radiation - do we need to control solar gains? Should we consider solar generation from PV panels?
• What are the prevailing wind conditions? How should the building be oriented to take advantage of natural ventilation potential?
• What other design strategies are appropriate for this climate?
• Do I need to do anything special to comply with a code or standard?

(NOTE: Include some text about limitations in pre-design and preview/link to later stage analysis)

Tutorial overview

Climate analysis during the pre-design phase is typically performed by analyzing an annual hourly weather data file. There are many different types of data included in a weather file and different approaches may be used to analyze, e.g., temperature data vs. wind data. In some cases, it is important to understand the interactive effects of multiple elements in the weather file. As you proceed through this page, links to additional tutorials will provide some of these more specific instructions.

Collect the project data

For this analysis, you must collect:

• The location of your project's site. This may be a specific address, or a more approximate location (e.g. zip code) if the site has not yet been selected.
• An appropriate weather data file. Refer to the page below for detailed guidance on selecting an appropriate weather file for your project, and where to get the files.
  • Tutorial: Weather data selection

Select an appropriate modeling software

add text here about the different types of tools used. Whole-building BEM tools, climate tools, PV tools

add note about file compatibility, and link to weather file type page

Input the project data

There is not really a need for providing inputs into the software tool because all of the weather data is already included in the weather file. The focus of this modeling task is analyzing the data to provide meaningful guidance, as discussed below.

In some advanced use cases, such as calibrating an energy model to measured data, you may wish to edit a weather file to match a nearby weather station if no AMY weather file (actual historical weather data) exists for the calibration period. These concepts are beyond the scope of this tutorial.

Analyze and present the results

Weather data is just data - lots of it. It includes 8760 hourly values for a large set of variables. Your job is to use this data to provide clear guidance to your project team on how the local weather may inform design features that are appropriate to the climate. Many different analyses can be performed by reviewing the weather data. See the links below for tutorials on how to effectively use this analysis to answer specific design questions.

How does outdoor temperature impact the design?

This analysis is done by reviewing outdoor temperature and humidity conditions at the site and determining how those values compare to acceptable thermal comfort conditions. It may help answer such questions as:

• When is the weather comfortable?
• Do operable windows for natural ventilation or free cooling make sense?
• When will HVAC systems be necessary for providing heating and cooling?

Refer to the the page below for instructions on how to analyze the weather data to answer these and other questions.

Tutorial: Climate analysis - outdoor temperature - design impacts

How does solar radiation impact the design?

This analysis is done by reviewing several solar radiation variables in the weather file. The analysis seeks to provide guidance to the design team to control solar gains and/or opportunities to generate on-site energy with solar photovoltaic panels. It may help answer such questions as:

• How can solar gains be controlled to prevent thermal and/or visual comfort issues?
• Does the site have potential for on-site renewable power generation?

Refer to the links below for further guidance on performing these analyses.

Solar gain control

Tutorial: Climate analysis - solar radiation - design impacts

Solar power generation

Tutorial: Climate analysis - solar radiation - renewable potential

How does wind at the site impact the design?

Tutorial: Climate analysis - wind data - design impacts

What design strategies make sense in this climate?

Early stage identification of appropriate design strategies

Tutorial: Identify potential energy efficient design options

Code modeling requirements

For projects following ASHRAE Standard 209, climate and site analysis is required for all projects by Section 5.3. The Standard states that the design team shall record the minimum following information for the project site:

• Dry-bulb temperatures (monthly minimum, maximum, and mean)
• Relative humidity or wet-bulb temperature (monthly minimum, maximum, and mean)
• Wind speed and direction (monthly average and maximum)
• Insolation (average daily per month)
• Cloud cover (monthly minimum, maximum, and mean)
• Ground temperature (monthly average)
• Precipitation (monthly total)
• Heating and cooling degree days, including base temperature for each (monthly total)

No example reports are provided, however it seems reasonable to assume that this data is intended to be recorded in tables. The intent of this requirement of Standard 209 is to ensure that the design team has a base understanding of typical and extreme weather conditions that will be experienced at the project site.

See also

• Weather file types

Additional resources

• Climate Consultant tutorial - a YouTube video demonstrating the capabilities of the Climate Consultant software, a popular tool for performing early-stage climate analysis.
• Autodesk blog post - Solar Radiation Metrics - a discussion of how solar radiation effects architectural design and definitions of solar radiation variables.
• EnergyPlus reference documentation - radiation metrics - descriptions of the solar radiation variables in EPW files.

Links to external websites are provided as a convenience for further research, but do not imply any endorsement of the content or the operator of the external site, as detailed in BEMcyclopedia's general disclaimers.

References

ASHRAE 209

Climate Consultant links

Taylor Engineering article on thermal comfort: http://www.taylor-engineering.com/wp-content/uploads/2020/04/ASHRAE_Journal_-_Sunlight_and_Indoor_Thermal_Comfort.pdf

DOE article about solar radiation: https://www.energy.gov/eere/solar/articles/solar-radiation-basics

DOE article about passive solar heating: https://www.energy.gov/energysaver/energy-efficient-home-design/passive-solar-home-design

https://www.designingbuildings.co.uk/wiki/Solar_gain_in_buildings