The reason a terrace cannot be used in winter is usually not temperature but wind. Even when the air is above ten degrees, wind strips heat from the body quickly and the area becomes impossible to sit in. In winter use, therefore, the first problem to solve is not heating but stopping air movement. A zip screen does exactly that; a heater only becomes meaningful once the wind is blocked.
The zip screen's technical advantage here lies in its edge lock. The fabric's side edges are fixed by the zip strip in the track, leaving no gaps at the sides. On a conventional outdoor curtain the fabric is blown aside and cold air comes in underneath; in zip screen systems that route is closed. What makes the difference in winter use is this edge detail as much as the fabric itself.
Fabric choice is decisive in a winter setup. Because screen fabric passes air it slows wind but does not stop it entirely; it falls short of retaining heat in winter. Crystal PVC is a non-porous surface that blocks wind and rain completely. Where winter use is the aim, the right setup is crystal PVC on the main façades and screen on sections needing daytime sun control. We covered fabric types in detail in this article.
Enclosing alone does not heat a terrace; it only slows the escape of heat. An enclosed terrace is a volume without thermal insulation: the surfaces are thin, the floor cold, the ceiling often single-layer. Enclosure and heating must therefore be planned together. Enclosing without adding a heater produces a result that does not meet expectations.
The first distinction in choosing a heater is how the heat travels. Convection heaters warm the air; the warmed air rises and collects at the ceiling, leaving little heat at seating level. Infrared heaters warm not the air but the surfaces and people in front of them directly, much like the sun. In a high-ceilinged, uninsulated terrace, infrared is markedly more efficient.
An infrared heater's position matters more than its power. Because the heat travels in a line, the direction the heater faces determines who gets warm. The right setup places heaters above the seating groups, angled slightly towards the seating area. A heater mounted flat on a wall warming the opposite wall wastes most of its energy.
Gas tower heaters are powerful but need care in an enclosed volume. Combustion products mix into the space; using them without ventilation on an enclosed terrace is not safe. Electric infrared heaters produce no such combustion products. If a gas appliance is to be used in an enclosed area, continuous air exchange must be provided and the manufacturer's warnings about enclosed-space use must be observed.
The second technical problem of an enclosed terrace is condensation. Humid air inside turns into water droplets when it meets a cold surface. On cold surfaces such as crystal PVC and glass this shows as misting and dripping. The source of humidity is not only the air; breath, hot drinks, wet outerwear and any potted plants all add to it. That load must be factored in when planning enclosed use.
The remedy for condensation is ventilation, which seems contradictory at first because letting air in loses heat. The correct method is intermittent rather than continuous ventilation: closing the area fully and opening it completely for short periods at intervals is both more effective and less heat-costly than leaving a permanent gap. A motorised zip screen makes this practical.
The ceiling side is the most neglected part of a winter setup. Even with the side façades enclosed, heat escapes straight upwards in an area that is open or permeable above. In zip screens installed under a bioclimatic pergola, the louvres locking together with EPDM gaskets in the closed position largely stops that loss. With fabric pergolas or open overhead setups, expectations of warming should be kept more modest.
The floor also has more effect than expected. Cold concrete or ceramic flooring is a constant source of cold at foot level, and an infrared heater spends part of its energy warming that surface. Outdoor-grade rugs, timber decking or composite floor coverings markedly reduce the cold at foot contact. That is a cheaper and more effective intervention than increasing heating power.
Stopping air movement entirely on an enclosed terrace produces another effect: heat stratification. Warm air collects at the ceiling while seating level stays cold. In high-ceilinged areas this difference is pronounced. A small circulation fan pushes the warm ceiling air down and delivers greater comfort from the same heater output. A low-power fan can be more useful than an extra heater.
In commercial use, the winter setup relates directly to turnover. Café and restaurant terraces turn into dead space over the winter months if they are not enclosed. A terrace enclosed with zip screens stays usable even if it does not reach the same occupancy as indoors. An added advantage here is that the system opens fully out of season: in summer it rolls into the cassette and the façade stays open. We covered hotel and restaurant applications in this article.
It is worth saying what not to expect from winter use. A terrace enclosed with zip screens is not a thermally insulated interior; it does not reach indoor temperature, nor is it meant to. The aim is an area free of wind and rain where, supported by a heater, you can sit comfortably. If indoor comfort is expected, a winter garden built with insulated glass systems is the right solution.
In summary, winter terrace use is built in four steps: an edge-locking zip screen to block wind, crystal PVC fabric on the main façades, infrared heaters aimed at the seating groups, and intermittent ventilation to manage humidity. Floor covering and a small circulation fan complete the setup. Planned correctly, the terrace becomes an area usable for most of the year.
To plan your terrace's winter setup together with wind direction and heater positions, request a free site survey.
Frequently Asked Questions
No, it does not heat; it blocks wind and slows the escape of heat. For winter use, enclosure and heating must be planned together.
Electric infrared. Because it warms people and surfaces directly rather than the air, it is more efficient on high-ceilinged terraces; gas appliances produce combustion products and require ventilation in enclosed areas.
With intermittent ventilation. Rather than leaving a permanent gap, closing the area fully and opening it completely for short periods at intervals is both more effective and less heat-costly.
