Building Design

Ecotect & Vasari: Climate Analysis

Weather data is available in Autodesk Ecotect’s Weather tool and in Autodesk Vasari or Revit. For more documentation on these tools, see:

Workflow Diagram

Get you started with Autodesk’s climate analysis tools.

 

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Temperature and Humidity

Understanding temperature and humidity can help you determine which passive cooling or passive heating strategies to use.

Psychrometric charts are the most commonly used tool for analyzing this aspect of the climate. A robust psychometric chart tool is available within the Ecotect Weather Tool. With this tool, it is possible to overlay human comfort zones onto the chart, see how much these different passive strategies help expand that comfort zone, and how much energy you’ll be able to save by avoiding active heating and cooling.

For more detail on psychometrics, see the Ecotect Natural Frequency Wiki.

 

Heating and cooling degree days (learn more) is another common way to understand how much heating and cooling you’ll need to do (either passively or actively).  In Ecotect, you can calculate the heating and cooling degree days within the Thermal Analysis tab based on your model and your climate.

For this building in Nashville, TN this Ecotect graph of degree days (DD) shows that you’ll need some cooling in the summer months and (relatively more) heating in the winter months.

 

Diurnal temperature data shows daily cycles of temperature and radiation on the site. Each “column” in the chart shows data over the course of a typical day in that month. While both Vasari/Revit and Ecotect present diurnal weather data, the two tools present that data differently.

This graph of diurnal averages from Nashville, TN is from Ecotect. The full range of dry-bulb temperatures is plotted, and wet bulb temperature is not. During the winter months, the temperature range is well below the comfort zone, so we’ll likely need to use mechanical heating (though solar radiation is high during the day). During the summer months the temperature ranges are close to the comfort zone so we’ll likely be able to condition the building passively (although there is a larger temperature swing from night to day). 

This diurnal weather chart from Vasari/Revit is also from Nashville, TN. However, it is read differently.

Wind

Wind rose diagrams plot the wind speed and direction. This data is available in Autodesk software in both a “speed distribution” or a “frequency distribution.”

 

In Vasari/Revit: Interactive wind rose diagrams are available in Vasari using the Wind Rose Tool (it is labeled “Ecotect Wind Rose”, because this functionality originated in that program). Static wind rose images for both annual and monthly data are also available as part of every “Results and Compare” report for conceptual energy analysis in both Vasari and Revit.

 

A frequency distribution from the Wind Rose Tool in Vasari, showing annual averages.

 

Vasari also allows you to overlay a wind rose diagram onto your building site. (Wind speed chart from San Diego)

 

 

In Ecotect: Wind rose diagrams are available in Ecotect in the Weather Tool. The data in Ecotect can also include temperatures, humidity, and rainfall – so you can see if the wind will be warm or cool, wet or dry.  

Wind data in Ecotect (frequency diagram), also showing wind temperatures, rainfall data, and relative humidity. Strong, cold winds come from the northwest – but not very often. Most of the time the wind blows from the south, and that wind tends to be warm and have a comfortable 55% relative humidity.

 

Sun

The solar position can be visualized in Vasari, Revit, and Ecotect. The sunpath tool overlays an interactive dome on top of your model within the design wind so that you can visualize the sun’s position at specific times of day and year. If you turn shadows on, those shadows will move as you move the sun in the sky.

The sunpath diagram on a building placed in Nashville, TN and visualized at noon on the winter solstice, the shortest day of the year (December 21). Sunset and sunrise times are shown in orange and red.

 

This sunpath tool is a more intuitively visual representation of the same data that is available in the Ecotect Weather Tool (Solar Postion tab). However, Ecotect’s Solar Tool also offers a wide range of solar position tools to help with detailed analysis. 

 The same sun position as the Vasari image from Nashville, but visualized in Ecotect’s solar position tool and including tabular data. 

 

Seeing how the sun will move in the sky and shine on your site is helpful for optimizing both passive heating and daylighting strategies.

Learn more in the Sun and Shadow Studies in BIM section.

 

The solar radiation that’s available on your site gives you a fuller picture of how the sun should influence your design. Understanding direct and diffuse solar radiation will help you determine if you can use direct solar gain passive design strategies and if the site is suitable for generating solar energy.

Solar radiation data is available through Revit and Vasari within the Diurnal temperature charts that are part of the “Results and Compare” energy analysis reports.

Direct and diffuse solar radiation are depicted in the purple and light blue lines on this diurnal weather averages chart for Nashville, TN.

The Ecotect Weather Tool’s hourly data tab has data on cloud cover, direct solar radiation, and diffuse solar radiation to give you a better sense of your site throughout the day and throughout the year.

Ecotect Weather Tool chart on incident solar radiation throughout the year (coldest months in blue, warmest months in red).

Ecotect Weather Tool charts on direct radiation, diffuse radiation, and average cloud cover in Nashville, TN.

 

Learn more in the Solar Loads Analysis in BIM section.

 

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