Radiant Tube heaters work by being fixed to the ceiling and targeting infrared radiant heats towards to floor by a reflector. If you were to imagine standing in front of a roaring log fire, or in direct sun light, you only feel the maximum benefit of the heat when you're directly in its path, as soon as you move away from the fire or out the sunlight you feel noticeably cooler. Radiant tube heating work along the same principle, the heats rays only travel in straight lines (like light) and are absorbed by cooler solid surfaces which they're aimed at rather than being aimlessly pumped into the air.
Radiant Tube heating can be incredibly cost effective because you're not wastefully heating a large warehouse or open plan building, you're just targeting a specific area which can have a positive impact on your business, not just from the savings you'll see in your heating bills but also in reducing your carbon foot print. In compliance with the Kyoto Protocol, the UK government is trying to ensure all UK businesses produce as little greenhouse gases as possible, which is why the climate change levy was introduced. The less harmful pollutants your business admits, the less tax you have to pay on them, in fact, if your business is serious about trying reduce it's carbon footprint, you may even be eligible for an Enhanced Capital Allowance or a Carbon Trust Loan to help cover the cost of the installation and maintenance of your radiant tube heaters.
The downside of radiant heaters is that they do only heat the area they've been targeted on, if you're after a heating system to heat a wider area you may have to consider another method such as propane heating, or a warm air blow heater.