A few years ago, when my youngest daughter was 5, her aunt asked he could she spell  " supercalifragilisticexpialidocious", my daughter looked at her very seriously and asked "can you spell cat"

I learned, that no matter how complicated the task, it starts with the basics.  

There are four basic ingredients that you need for comfort with energy efficiency.

1. Generate the heating, cooling and  ventilation efficiently

2. Distribute the heating, cooling and  ventilation efficiently

3. Control the heating, cooling and  ventilation efficiently

4. Retain the heating, cooling and  ventilation efficiently

When I'm asked why the energy bill is high for a building, I start with the four basic ingredients that are needed for economy:- generation,  distribution, control and retention. 

When designing a heating, cooling system or ventilation system, the four basics are the most important items to consider and these are balanced with the capital costs and live cycle costs to offer the best value for the customer.

You've got to be able to spell cat first before you can spell supercalifragilisticexpialidocious

Eamon