Understanding Results


1. Wind Rose Explained

Wind Roses are helpful tools which display wind speed and direction at a specified season and location, but may be a bit difficult to interpret.

1.1 What is it measuring?

The Wind Rose displays three types of information: 

  • The speed at which wind is blowing
  • The direction from which wind is blowing 
  • How often wind blows from a particular direction at a particular speed

Wind direction (where wind is blowing from, not towards) is displayed in a compass configuration.

The shade of each ‘spoke’ of the wind rose indicates a range of speeds at which wind blows, based on the legend displayed at the bottom. For instance, winds blowing from a particular direction may typically be low-speed, but might occasionally become much stronger.

Finally, the radiating rings – and the accompanying numbers displayed with each ring – indicate how often wind blows from that direction at various speeds. This is shown as a percentage. 

1.2 How to Read a Wind Rose

During the Spring season at Toronto Pearson Airport, wind blows from due East for a total of 4.6% of the season. These winds blow at:

0-10 km/h for ~0.5% of the season

10-20 km/h for ~1.2% of the season

20-30 km/h for ~1.8% of the season

30-40 km/h for ~0.8% of the season

40+ km/h for ~0.3% of the season.

Eastern Winds

From the southerly direction (see below), winds typically blow from the southeast. These SE winds are low-speed, typically blowing at 10-20 km/h, and do not exceed 30 km/h. Winds from the southwest – on the other hand – are far less frequent, but much more intense; when wind blows from the SW direction, they are typically above 20 km/h and sometimes exceed 40 km/h. Therefore, despite blowing less frequently than from the SE, these SW winds are considerably more impactful.

Southern Winds

2. Color Legends Explained

2.1 Pedestrian Level Wind Color Legend

Abridge Pedestrian Level Wind Comfort Color Legend

What is it measuring?

Pedestrian wind comfort (i.e. the perceived acceptability of the force of wind on a person). Abridged Comfort Criteria is a simplified version of RWDI’s criteria

What does the scale mean?

The color scale indicates three types of zones. These indicate what a specific location is best suited for (80% of the time or more, statistically):

  • Sitting – Calm or light breezes desired for outdoor restaurants
  • Strolling – Moderate winds that would be appropriate for window shopping or strolling down a street, plaza or park
  • Uncomfortable – Strong winds considered a nuisance for all pedestrian activities, mitigation typically recommended

What options can I specify?

The Season is defined by the user (or predefined for them) by specifying a range of months. All 24 hours in a day are used

2.2 Directional Wind Color Legend

Directional Wind Intensity Color Legend

What is it measuring?

The average wind speed at a location for a defined season and wind direction (337.5 is NNW)

What does the scale mean?

The color scale indicates three types of zones; low, medium and high. These indicate a relative wind speed/intensity for a given area. The colors should not be taken as an absolute; they are meant to only indicate whether a specific location is expected to experience acceleration or deceleration of wind intensity

What option can I specify?

The Season is defined by the user (or predefined for them) by specifying a range of months.

2.3 Thermal Comfort – SPMV HOT – Color Legend (Hot and Tropical) Climates

SPMV-HOT Thermal Comfort Color Legend

SMPV*

In an outdoor environment, the “Standard Predicted Mean Vote Modified” (SPMV*) metric is used as it can effectively account for the physics associated with elevated solar exposure and humidity ranges present outdoors. SPMV* is a modified version of the ASHRAE PMV metric which better accounts for the larger range of outdoor conditions.

Thermal comfort is a useful concept and SPMV* provides a method to communicate this concept.  Still, it should be noted that the SPMV* index is based on surveys and perceptions of individuals.  It is based on 80% of respondents agreeing on the condition they are feeling.  It is, in no way, a definitive measure of an individual’s thermal comfort.  Also, the variety of conditions and activities that impact the perception of comfort are large and varied.

Any thermal comfort analysis should therefore be viewed as a guide and not as a quantitative assessment.

What is it measuring?

Thermal Comfort scale for a given season (range of months), time of day period (range of hours), clothing and activity level. Thermal comfort is finding a perfect balance when people in outdoor spaces aren’t too cold, too warm, and when it’s neither too sunny, too cold, nor too windy for pedestrians.

What does the scale mean?

This is a SPMV* for hot and tropical climates. The color scale shows what the average thermal comfort conditions are at a location.

The color scale indicates four types of zone:

  • Comfortable: this location is similar to indoors. No thermal stress.
  • Acceptable: A person will generally accept this location as comfortable since they are outdoors. Some thermal stress.
  • Tolerable: A person will stay at this location for some time but will seek better conditions.
  • Unacceptable: Too hot. A person will seek cooler conditions.

What options can I specify?

The Season, Time of Day, Clothing Type and Activity Type is defined by the user (or predefined for them). Example:

2.4 Thermal Comfort – SPMV – Color Legend (Temperate) Climates

SPMV-TEMPERATE Thermal Comfort Color Legend

SPMV*

In an outdoor environment, the “Standard Predicted Mean Vote Modified” (SPMV*) metric is used as it can effectively account for the physics associated with elevated solar exposure and humidity ranges present outdoors. SPMV* is a modified version of the ASHRAE PMV metric which better accounts for the larger range of outdoor conditions.

Thermal comfort is a useful concept and SPMV* provides a method to communicate this concept.  Still, it should be noted that the SPMV* index is based on surveys and perceptions of individuals.  It is based on 80% of respondents agreeing on the condition they are feeling.  It is, in no way, a definitive measure of an individual’s thermal comfort.  Also, the variety of conditions and activities that impact the perception of comfort are large and varied.

Any thermal comfort analysis should therefore be viewed as a guide and not as a quantitative assessment.

What is it measuring?

Thermal Comfort scale for a given season (range of months), time of day period (range of hours), clothing and activity level. Thermal comfort is finding a perfect balance when people in outdoor spaces aren’t too cold, too warm, and when it’s neither too sunny, too cold, nor too windy for pedestrians.

What does the scale mean?

This is a SPMV* for temperate climates. The color scale shows what the average thermal comfort conditions are at a location.

The color scale indicates three types of zone:

  • Comfortable – this location is similar to indoors. No thermal stress.
  • Too Cold/Too Warm – a person will stay at this location for some time but will seek better conditions.

What options can I specify?

The Season, Time of Day, Clothing Type and Activity Type is defined by the user (or predefined for them).

2.5 Thermal Comfort – SPMV % Inbounds Color Legend 

Thermal Comfort SPMV % Inbounds Color Legend

SPMV*

In an outdoor environment, the “Standard Predicted Mean Vote Modified” (SPMV*) metric is used as it can effectively account for the physics associated with elevated solar exposure and humidity ranges present outdoors. SPMV* is a modified version of the ASHRAE PMV metric which better accounts for the larger range of outdoor conditions.

Thermal comfort is a useful concept and SPMV* provides a method to communicate this concept.  Still, it should be noted that the SPMV* index is based on surveys and perceptions of individuals.  It is based on 80% of respondents agreeing on the condition they are feeling.  It is, in no way, a definitive measure of an individual’s thermal comfort.  Also, the variety of conditions and activities that impact the perception of comfort are large and varied.

Any thermal comfort analysis should therefore be viewed as a guide and not as a quantitative assessment.

What is it measuring?

A SPMV thermal comfort scale showing the percentage of time an area is perceived as comfortable

What does the scale mean?

The color scale indicates the percentage of hours within a specified time frame that are within the comfortable range. Example:

  • 100% = All hours of the specified criteria (Season, Time of Day etc) and are comfortable in the location colored dark green

What options can I specify?

The Season, Time of Day, Clothing Type and Activity Type is defined by the user (or predefined for them).

2.6 Solar (% Sun Lit) Color Legend  

Solar (% Sun Lit) Color Legend

What is it measuring?

A theoretical shading scale that measures if the sky was clear every day of the year, this is where shadows would fall for the given Season (month range) and Time of Day (hour range)

What does the scale mean?

The color scale indicates the amount of shadow and/or sunlight an area is experiencing:

  • Black – fully shaded
  • Bright Yellow – full sun

0% means a location does not see direct sun at any time during the specified Season and Time of Day. 100% means it is never shaded and completely exposed to the sun.

What options can I specify?

The Season and Time of Day

2.7 Directional Wind Color Legend 

Directional Wind Color Legend

What is it measuring?

Average wind speeds at a location for a given season and wind direction

What does the scale mean?

The color scale indicates three types of zones; low, medium and high. These indicate a relative wind speed/intensity for a given area. The colors should not be taken as an absolute; they are meant to only indicate whether a specific location is expected to experience acceleration or deceleration of wind intensity.

The streamlines show how and where the wind flows around the buildings and space

What options can I specify?

None, this scale shows a relative flow and the plots are not seasonal nor scaled for climate data. Year-round conditions are used


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