This week I caught up with Alex Reiche for the very first Home Style Green expert interview. 

Alex Reiche is the Founder and Managing Director of EnviroSpec, an online register of 'Eco-Preferred' products. 

Check out EnviroSpec's interacitve house to find the best products for your building project. 

Alex is also an accredited Homestar and Green Star professional and offers design and certification advice for residential and commercial buildings. 

In today's cast, I complete our introduction to heating systems with a look at central heating. 

Common to all central heating systems are three main components:

1. The fuel

2. The engine or heater

3. The distribution system - pipes, ducts and outlets

There are two main mediums for transfering heat. Air is common with gas-fired heaters and large ducts but is not as effective as water based systems.

Air ducts can lose up to 1 degree per m of duct. 

Heating that is not true central heating includes inslab or undertile electric element heating, heat transfer and ventilation system. 

After insulation, heating is the next thing most people look at when improving the comfort and warmth of their home. 

In this episode of Home Style Green, I discuss room heaters:

• Standared electric heating: electric fan heaters, bar radiators, oil column, wall panel etc
• Gas unflued heating: And why you should never use it!
• Flued gas heating
• Heat pumps or reverse cycle air conditioning

In the episode I refer to the 'carnot cycle'. This is the awesome thermodynamic principle behind air conditioning and refrigeration. Refer again to our trusty Wikipedia for a good article about the detailed physics:

http://en.wikipedia.org/wiki/Carnot_cycle

Of course the best form of heating is free from the sun. But making the most of passive solar heating is a design challenge and there's usually not a lot that can be done to improve this once a house is built.

So if you're trying to heat an existing, cold home, what's the best option?