Patio heater

This reduces the amount of heat lost by conduction as silvered surfaces will not absorb infrared light.

[1] The use of external heaters outside cafes has been banned in various cities in France & Germany, due to environmental concerns, starting with Rennes.

[3] Propane patio heaters are the most popular type, as they are portable and easy to find refill locations such as gas stations or convenience stores.

The downside to propane is that you need to purchase a separate tank for each heater you own and can be more costly to operate than electric or natural gas.

Electric patio heaters are a great choice for easy setup, and has indoor applications as well, for partially enclosed indoor-outdoor space.