Greennav goes to Cape Town – Pimp the blog

November 24, 2008

Blogging will slow for the next 2 weeks on this blog as I’m off to Cape Town on the Niall Mellon Township Trust Builders Week 2008.


The plan is however to blog through the week on the sights and sound of the week on my new personal blog Please help out by

  • Making a donation to the NMTT (Directly or through whoever you know who is collecting)
  • Sign up for next year
  • Write a post about the NMTT on your own blog during the week
  • Put a NMTT (or other charity) button on your side bar (you can steal mine)
  • Pimping my blog to others ( who might do one of the above – lets face it….. this is what I really want to happen)

External Insulation

November 24, 2008

In cases where existing houses require wall insulation but do not cavity wall insulation is not a viable option, the more expensive option of installing of external insulation may be considered. External insulation involves fixing insulation materials such as mineral wool or expanded polystyrene slabs to the outer surface of the wall. This insulation is covered with a special cement-based render or aluminium skin to provide weather resistance. The insulation forms a barrier to heat transfer and reduces losses through the wall space. One of the main benefits of the external insulation over internal insulation is that loss of internal space is avoided. When installing external insulation, it may be necessary to extend eaves and sills and relocate downpipes to accommodate the extended footprint of the building.


Another important characteristic of external insulation is that it will maintain the houses heavy weight slow thermal performance. This means that the houses walls will absorb some of the heat when the heating is switched on, reflecting it back into the house after the heating has been turned off. The disadvantage however is that it will take longer for the heating system to heat the house up in the first place.


Another advantage of external insulation is the chance it allows for upgrading the aesthetics of the house. The chance to re-clad an aged house is often a major attraction to external insulation. This benefit can also be essential to making the economics of a project.





Obama says few words

November 19, 2008

Lets hear it for the big fella…

What is CHP (CoGeneration-Combined Heat and Power)

November 16, 2008

In the push for alternative energy solutions in regular homes, Combined Heat and Power (CHP) has become an area of much interest. In the domestic setting CHP, or “MicroCHP” combines onsite electricity and heat generation (your boiler). The MicroCHP which has a traditional Natural Gas connection, combines the functions of an electrical generator, and a boiler, to generate electricity and hot water. This works well as generators generally create waste heat, but in a CHP format, this heat is used to heat water. The efficiency gained by combining the two functions is significant, usually providing 37% electricity and 45% hot water in relation to the gas imputed. This combined efficiency of 82% is a large improvement on traditional means (55% – 62%).

The electricity generated by the MicroCHP is then used in your house to reduce the amount of electricity you buy from grid. The

 So… do they work? Well its like this. In a normal house you have the heating switch on when you need the heat, and that’s it. When you have a Micro CHP, the situation is similar, it switches on when you need heat, but that is the only time that you will be getting electricity from it. So if you have the heating switch on in the morning, then at that time you’ll be getting cheap electricity, but you may not really need that electricity.

Larger CHPs are common in hotels, swimming pools, hospitals, and industry. In these places they aim to have the CHPs operating for over 4000hrs a year (about half the time). In your house, it is unlikely that you would have it on for more that 1000hrs a year.

My verdict… draft proof your windows…

District Heating System

November 9, 2008

District Heating System’s links the heating systems of a number of dwellings, buildings or units on a site or development. These links allow the system to transfer heating from one site to another increasing efficiency. This is achieved by using larger more efficient equipment located in the basement, by matching thermal demand on different sites to maximise efficient plant operation, and by using Renewable, Sustainable or Alternative Heating. It also creates cost efficiencies through improved management, reduced maintenance and the bulk purchase of fuel.


So does it work. Well like all large systems it comes down to the management. A well managed district heating system is far more efficient than individual well maintained boilers. In some cases I’ve come across systems that are horribly badly designed and managed. These ones suck and give the rest a bad name.

Trending oil and diesel prices

November 3, 2008

Since April 07 I’ve been keeping my diesel reciepts (for work). Though diesel and petrol (gas) prices haven’t followed each other perfectly, its still an interesting graph. I’d like to see what it would look like if I also fed in the €/$ exchange rate… there is always more you could to do with excel… 

Graph of Oil and Retail Diesel Prices (Gas prices)

Graph of Oil and Retail Diesel Prices (Gas prices)

Notes – These prices come from random service stations, though I do try and go to the cheaper ones

Thanks to the Energy Information Administration for the oil prices

Why environmentalists have a bad reputation

November 1, 2008