Greening Your Balcony and Courtyard to Cool Your Home
In Paris, where concrete and stone dominate the urban landscape, every square metre of greenery counts. Plants are not just decorative — they genuinely cool the surrounding air. According to ADEME, a mature tree evaporates approximately 450 litres of water per day, producing a cooling effect equivalent to 5 air conditioners running 20 hours a day. At the scale of a balcony or building courtyard, the gain is measurable. Here is how to go about it in a Parisian context.
The Cooling Effect of Plants: How It Works
Two mechanisms work simultaneously:
Evapotranspiration
Plants absorb water through their roots and release it as vapour through their leaves. This process consumes solar energy — exactly like human perspiration cools the skin. The solar energy "captured" for evaporation is no longer available to heat the air. Result: the air temperature near plants can drop by 2 to 5 °C.
Shading
Dense foliage intercepts solar radiation before it reaches the ground or walls. A green pergola above a terrace or balcony can block 60 to 80% of direct radiation — comparable to an exterior awning, with the added benefit of evapotranspiration.
What to Plant on a Parisian Balcony
A balcony offers specific conditions: wind exposure, limited space, load-bearing capacity to respect, and variable sunlight depending on orientation. Plant choices must account for these factors.
For a south-facing balcony (sunny, hot):
– Climbing plants on trellis: star jasmine, passionflower, Virginia creeper — they create a green screen that shades the facade and windows
– Lavender, rosemary, sage — resistant to heat and drought, minimal watering
– Potted olive tree — handles urban heat well
For a north-facing or shaded balcony:
– Ferns, hostas, heucheras — dense foliage that maximises evapotranspiration even in shade
– Ivy — grows fast, covers surfaces, moderate cooling effect
To maximise the cooling effect:
– Favour large leaves (fine foliage evapotranspires less per unit of surface area)
– Plant densely: the more plant mass, the greater the evapotranspiration
– Use deep containers (minimum 30 cm) for good root development and better water retention
Courtyard and Building Base in Co-Ownerships
This is where the potential is greatest. A mineral courtyard (asphalt, paving, gravel) functions as a heat trap — it stores the sun's heat and releases it at night, directly contributing to the urban heat island.
Greening the courtyard transforms this space:
– Planting trees (if the area and structure allow): a single medium-sized tree is enough to lower the temperature by 2–3 °C within a 10–15 metre radius. Plane trees and linden trees are well suited to Paris.
– Replacing asphalt with permeable surfaces: stabilised gravel, grass-filled paving stones — rainwater infiltrates and evaporates instead of running off
– Installing collective planters: containers along walls, planted building bases, green walls
– Creating a green pergola: wisteria, vine, hops — natural shading that protects ground-floor windows
The Co-Ownership Process
Greening the courtyard is a collective project that requires a general assembly decision:
1. Present the project to the property manager, with a landscaper's quote and a maintenance plan
2. Check the ground's load-bearing capacity (some courtyards are built over a slab, not natural ground)
3. Plan a suitable watering system (drip irrigation, rainwater collection if possible)
4. Add the item to the agenda of the next general assembly
The City of Paris greening permit also allows planting at the building's base, on the street side — an individual right that does not require co-ownership approval.
Responsible Watering During Drought
Urban greening means watering — and in a Parisian summer, water can be a strained resource. A few principles to balance greenery and water conservation:
– Water in the evening or early morning (never in full sun — 50% of the water evaporates before reaching the roots)
– Mulch containers and planters: 5–10 cm of mulch reduces evaporation by 30–50%
– Install drip irrigation: uses 30–50% less water than a watering can
– Choose Mediterranean plants (lavender, rosemary, olive, agapanthus) that tolerate drought once established
– Collect rainwater if the configuration allows (downpipe diverted to a tank)
Limitations and Maintenance
Greening is not an alternative to air conditioning — it is a complement that improves baseline comfort. A green balcony can lower the perceived temperature by 2–3 °C, which is significant but insufficient during an intense heatwave episode (above 40 °C).
Maintenance to plan for:
– Regular watering (daily during heatwaves for balcony containers)
– Pruning and cleaning of climbers (prevent them from invading the facade or blocking gutters)
– Substrate replacement every 2–3 years in containers
– Pest monitoring (aphids, scale insects — common in urban settings)
For thermal comfort beyond what greening can offer, Réseau Tubulure can help you choose and install air conditioning suited to your Parisian home. Contact us for a free quote.
Frequently Asked Questions
Do plants really cool the air?
Yes, measurably. Plant evapotranspiration consumes solar energy to turn water into vapour, which lowers the air temperature nearby by 2 to 5 °C depending on vegetation density. ADEME estimates that a mature tree produces a cooling effect equivalent to 5 air conditioners. The gain is especially noticeable in a confined space (building courtyard, balcony).
What can be done about the shared courtyard in a co-ownership?
Greening the courtyard is a co-ownership project that goes through the general assembly. Prepare a dossier (plan, landscaper's quote, maintenance plan, documented thermal benefits) and propose it to the property manager for inclusion on the general assembly agenda. At the building base on the street side, the City of Paris greening permit allows planting without co-ownership approval.
Which plants for a south-facing balcony?
Favour Mediterranean plants resistant to heat and full sun: lavender, rosemary, sage, potted olive tree, agapanthus. For shading, climbing plants on trellis are the most effective: star jasmine, passionflower, bougainvillea (in a pot, brought inside for winter). Avoid woodland plants (ferns, hostas) that will scorch in full sun.
Contact Réseau Tubulure
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