CO-MODELLING WATER AND
Figure 13
Taasinge Plads, Copenhagen, Denmark (Courtesy GHB Landskabsarkitekter / Steven Achiam)
Figure 14
Taasinge Plads, Copenhagen, Denmark (Courtesy GHB Landskabsarkitekter / Steven Achiam)
Much research has been undertaken to describe the effects of surface coverings and geometries on microclimates, but the vegetation aspect has often been neglected. Plants and trees also contribute to the thermal comfort of outdoor spaces.
They block the wind, thereby creating shelter, and furthermore, trees create shade from direct sunlight. These effects are well described and can be computed in practice. However, the effects of evapotranspiration of plants and trees on the microclimate are not well described within the building engineering disciplines.
THE LIVESTOCK PLUGIN
Livestock is a software plugin created to make up for the lack of knowledge of the effect of vegetation in the built environment and was first introduced in [5]. Livestock is a package for Grasshopper providing components for modelling water movement and hydrothermal effects around buildings to enable and evaluate sustainable solutions in which those effects are incorporated.
Livestock and its hydrological simulation engine can compute the evapotranspiration of plants and thereby enhance the current methodology of outdoor comfort evaluation.
By creating a good outdoor space, it is meant to control several factors such as stormwater management, and better outdoor microclimate can be acquired. Even though these seem unrelated, they are connected and can be used to influence each other.
The nature of the hydrological engine within Livestock makes it possible to evaluate both stormwater management and evapotranspiration. Situations such as the 2011 Copenhagen stormwater event, which caused parts of the northern part of the city to become flooded, show that there is an urgent need to tackle these problems.
A recent example of coupling between stormwater management and recreational space is the Taasinge Plads project in Copenhagen conducted by GHB Landskabsarkitekter (see Figure 13 and Figure 14). They introduced vegetation to a square in the neighbourhood of Østerbro. The green areas both function as recreational spaces and as stormwater basins, which would prevent flooding of the buildings around the square. While it might not have been the top priority of the design team, they also influenced the thermal comfort of the square by changing the urban fabric and increasing the evapotranspiration of the area.
Figure 15
Stormwater run-off analysis conducted for Philadelphia Zoo (Courtesy Bjarke Ingels Group)
The run-off capabilities of Livestock were used to calculate a stormwater event at the zoo in Philadelphia, USA (Figure 15). The analysis was done as part of a larger assessment of sustainable design options for the Zoo. The main prospect is to collect rain water, redistributing it, cleaning and using it for multiple usages, such as animal sea- and freshwater tanks, park toilets, watering plants and more. The runoff analysis was used to estimate the volume of water to expect and where to collect the water for all these purposes. Another use of the analysis was the resilience aspects and how to design hard surfaces to withstand extreme flood events and storm water prevention that may harm the park wild life. The analysis helped take action on the entire landscaping as well as the more technical sewage distribution system.
Figure 16
Effect of evapotranspiration on UTCI in Abu Dhabi (Source: [5])
whitout livestock whit livestock
UTCI - °C
1st of january
1st of june
55.0 52.5 50.0 47.5 45.0 42.5 40.0 37.5 35.0 32.5 30.0 27.5 25.0 22.5 20.0
whitout livestock whit livestock
UTCI - °C
1st of january
1st of june
55.0 52.5 50.0 47.5 45.0 42.5 40.0 37.5 35.0 32.5 30.0 27.5 25.0 22.5 20.0
with livestock without livestock
january 1st
june 1st
whitout livestock whit livestock
UTCI - °C
1st of january
1st of june
55.0 52.5 50.0 47.5 45.0 42.5 40.0 37.5 35.0 32.5 30.0 27.5 25.0 22.5 20.0
whitout livestock whit livestock
UTCI - °C
1st of january
1st of june
55.0 52.5 50.0 47.5 45.0 42.5 40.0 37.5 35.0 32.5 30.0 27.5 25.0 22.5 20.0
whitout livestock whit livestock
UTCI - °C
1st of january
1st of june
55.0 52.5 50.0 47.5 45.0 42.5 40.0 37.5 35.0 32.5 30.0 27.5 25.0 22.5 20.0
whitout livestock whit livestock
UTCI - °C
1st of january
1st of june
55.0 52.5 50.0 47.5 45.0 42.5 40.0 37.5 35.0 32.5 30.0 27.5 25.0 22.5 20.0
Livestock was also used to evaluate the benefit of trees and a water stream in a new neighbourhood in Abu Dhabi [5]. Abu Dhabi is located in a hot and dry climate, and throughout most of the year the air temperature is above 20°C, and it is not unusual to have temperatures above 40°C. These temperatures make it an ideal location for the use of evaporative cooling. The analysis was centred around a small area on both sides of a wadi. The investigation compared the UTCI in a situation where evapotranspiration from the trees and the water in the wadi were neglected and one where Livestock was used to calculate the evapotranspiration of the trees and water. The charts (Figure 16) show a clear benefit of the evapotranspiration on the UTCI. Under the trees during the summer, there is almost a 15°C difference in UTCI between computing with and without evapotranspiration.
The water vapour is assumed stationary in the current implementation of Livestock, meaning it will not mix with the air outside of the mesh face where it was created. In reality, this is of course not correct as water vapour would be dispersed by and mix with the wind/airflow. The current state of Livestock is the first step towards computing the influence of water and the influence of water vapour on the microclimate. The case studies show the usefulness of Livestock in the design phase, where it can be used to make more informed design decisions and designs with greater biophilic integration.
REFERENCES
[1] UNDESA, World Urbanization Prospects. 2014.
[2] J. Gehl, Cities for People, 1st ed. Copenhagen: Bogværket, 2001.
[3] T. R. Oke, ‘Canyon geometry and the nocturnal urban heat-island - comparison of the scale model and field observations,’ J. Climatol., vol. 1, no. 3, p. 237-, 1981.
[4] M. Roth, ‘Urban Heat Islands,’ Handb. Environ. Fluid Dyn. Vol. Two, pp. 143–159, 2013.
[5] C. Kongsgaard, ‘Hygrotermic Control of the Microclimate,’ Technical University of Denmark, 2018.
Since we spend 90 per cent of our daily lives indoors, designers must make our indoor environments as comfortable as possible.
Our approach to design must address the reality of an indoor- dominant modern lifestyle but must also proactively work to make outdoor public spaces as comfortable and accessible as possible. It is critical that we provide liveable, well-ventilated and healthful spaces, and foster a close relationship between interior spaces and outdoor access. At Henning Larsen, the aim is to draw on contemporary research and broad knowledge bases to create design parameters that encourage these healthful interiors. Urban microclimates are defined by a local set of atmospheric conditions -- wind, sun, humidity, -- that have a significant influence on the concentration of air pollutants, thermodynamics and air quality.
Here, we explore some of the core concepts that maximise our regular exposure to the natural world, both in bringing nature into our interior spaces and by reframing outdoor areas as cities’
active social spaces. These concepts are illustrated using their application in a real-life case study, the Etobicoke Civic Center in Toronto, Canada (see Figure 17-21). By means of microclimatic analyses, the outdoor season of the squares and courtyards accompanying the building has been extended by five weeks.
EXTENDING THE OUTDOOR SEASON BY DESIGN
One of the most common barriers to greater outdoor engagement is an inhospitable local climate. Outdoor recreation is an unappealing option for well over half the year, owing to severe cold, heat, precipitation, darkness or other factors. However, architects and urban planners have a unique opportunity to extend the outdoor season by integrating urban physics and climate knowledge into urban planning. Deliberate building massing, landscape design and shading strategies can help reclaim the outdoors for the public realm by creating more comfortable microclimates, shielding building users from the environmental factors that might drive them indoors.