Summer puts urban heat islands on full display. The same spaces that work well in spring become hostile in July. Pavements, benches, facades, and street furniture absorb heat throughout the day and release it slowly through the night, leaving streets and squares uncomfortable long after sunset.

Trees address that discomfort by intercepting solar radiation before it reaches hard surfaces, reducing the heat absorbed and re-emitted by pavements and walls. What is less straightforward is translating that principle into precise, project-specific data: measuring this cooling, calculating exactly how much, where, and under what conditions. This capacity of vegetation to lower surface temperatures in the urban environment is what we refer to as the cooling effect, and it is here that the design model becomes the key instrument.

Canopy geometry as the basis for calculation

The accuracy of any cooling effect analysis depends directly on the quality of the vegetation model it draws from. Canopy shape, density, height, and seasonal variation all determine how much radiation a tree intercepts and what surface area falls under its shadow at any given moment. A canopy geometry defined by species and calibrated by age produces results that are meaningful for the specific project being designed.

The botanical library in RhinoLands covers more than 8,000 species with morphological data that scales with age, with each species projecting distinct shadows across the surfaces below. That specificity is what elevates the RhinoLands model from a representation of the design to a useful computational basis for environmental analysis.

Linked to Ladybug tools through Grasshopper, the vegetation model becomes the direct input for surface temperature calculation. Using the UTCI thermal comfort model, the outdoor thermal index used as standard in environmental meteorology, the analysis returns surface temperature values under and outside the canopy for any date, time, and geographic location. The results are mapped as colour gradients directly onto the model, making the thermal impact of each tree immediately legible and comparable across design alternatives.

Surface temperature analysis calculated from vegetation models added through RhinoLands Grasshopper components.

See the full workflow: How to Calculate the Cooling Effect of Trees in the city

Applied to an example with a group of trees in Madrid, the analysis recorded a surface temperature reduction of 7°C, from 38.8°C to 31.7°C, on July 15th under the canopy. In winter, with the same deciduous trees bare of leaves, the shaded area contracted by 80% and surface temperature under the leafless canopy remained at 13.09°C on January 15th, allowing solar radiation to warm the surfaces below when thermal comfort demands precisely that. The seasonal behaviour of the canopy becomes not just a design consideration but a quantifiable performance variable. The Grasshopper definition used for this analysis is freely available on Food4Rhino for anyone working in the Rhino and Grasshopper environment.

Surface temperature analysis under tree canopy in summer and winter showing seasonal thermal variation.

Analysis as part of the design process

Running this analysis within the design environment, rather than in a separate tool, changes the role it plays in the project. When thermal performance data is generated inside the same model used to make spatial decisions, it informs those decisions in real time rather than validating them after the fact. A landscape architect who can demonstrate, within the project model itself, that a specific planting arrangement reduces surface temperature by a measurable margin at the most critical point of a summer afternoon, has a technical argument with real weight in front of clients, municipalities, and planning authorities. The user project A Landscape Node in Madrid by Alberto Ferrero de la Vega shows how this kind of integrated workflow between environmental analysis and vegetation design is already being applied in built projects developed with RhinoLands and Grasshopper.

Solar radiation incidence on plants

Surface temperature is one dimension of the environmental analysis that the RhinoLands model supports. The same geometric precision that makes cooling effect calculation possible also underpins the analysis of solar radiation received by each plant in the model, data that informs species selection based on real light conditions within the project, identifies understorey vegetation at risk of light deficit, and evaluates how the canopy coverage of established trees shapes growing conditions for everything planted beneath them.

Solar radiation values received by tree objects, calculated from the vegetation model.

See the full workflow: How to Calculate the Solar Radiation Received by Plants 

RhinoLands is the standalone version that combines Lands Design with Rhinoceros 3D in a single integrated interface designed for landscape architecture workflows. Available with a 60-day free trial at rhinolands.com/download.

For those already working in the Grasshopper environment, both the cooling effect and solar radiation definitions are freely available on Food4Rhino.