Understanding – Immersion heaters – hotwater cylinders

February 29, 2008

Immersion heaters, otherwise known as electric water heaters or hot water cylinders, double as water heaters and hot water storage systems. Most combine a number of heat sources to maximise the flexibility of the system.

Understanding - Immersion heaters - hotwater cylinders

The typical hot water storage cylinder has two electric elements and one or more hot water heat exchangers. These electric elements and heat exchangers heat water in the cylinder to be used for hot water in the house, operating in an order which best provides the hot water as efficiently as possible.

Firstly, most immersion heaters are heated by the main boiler system. A heat exchanger inside the cylinder is piped from the boiler, though is often on a different circuit than the heating system (so the heating can be switched off without switching off the hot water from the immersion). As electricity is more expensive than other fuels in most countries it is cheaper to run than the electric elements, and so is the default option.

Next, a small electrical element located towards the top of the cylinder is used to heat small quantities of hot water. In many switching arrangements this the control for this element is marked “sink”, though it is generally sufficient to provide water for a shower.

A higher rated electrical element is located lower down in the cylinder and can be used to heat the full cylinder (often marked “bath”). Electrical heating is generally quite easy to use and for this reason it is quite popular, but it is by far the most inefficient from an environmental point of view, and also the most expensive.

In many cases renewable heating systems such as solar panels or geothermal systems are also piped into the immersion heater. Heat exchangers reject heat from these systems into the immersion heater, heating in a similar fashion to the central heating system. In some cases these renewable systems can not heat the water to a sufficient level, and so require conventional methods to heat the water the final amount. While this is not an ideal situation, the energy required from the conventional methods to heat the water the last bit is significantly reduced.

Understanding – how condensing boilers works

February 27, 2008

Ok… So post assumes you’ve just checked out this post about how a boiler works… then what about these condensing boilers then…

Condensing boilers have all the same elements as standard boilers, but have increased efficiency. The efficiency of a boiler is a measure of its ability to convert energy from the fuel that goes in, to heat in the water that circulates around your house. Condensing boilers do this by having an extra heat exchanger in the flue. As the flue gases (fumes, smoke… and the like) heat up the water (or some cases the air) a bit as it is feeding into the boiler. This means that the boiler has less work to do to heat the water in the main body of the boiler. It also means the flue gases are cooled down a bit more than usual, and so some of the particles in the gases will “condense”. The condensed liquid can be a bit nasty, and so higher quality materials are necessary in the boiler. This causes the boilers to be more expensive but the reduction in fuel costs can be significant.

Understanding - how condensing boilers works

Another key point to note is that the flue gases are at a far lower temperate than the gas straight after the burner. This lower temperature gas is really only good for heating cooler water, and so works best on a lower temperature system. So with condensing boilers, the lower temperature you run the system, the more efficient they run.

Lower temperature systems means the water circulating around your house will be at cooler, meaning that you will either

need larger radiators (or have underfloor heating)

Accept that it will take longer for them to heat up the room (not a lot, just a bit)

Bokashi – and the Art of Apartment Waste Composting

February 26, 2008

So you are living in one of the many apartments that have been thrown up by builders across Ireland

Like me

You recycle the paper and plastic, but you also want to reduce the amount you are adding to the landfill.

Like me  

Builders should have put in some compost heap with the bin sheds – but of course they didn’t.

So I bought a Bokashi composting system.  Two 17 litre buckets designed to be used in rotation – two weeks worth of kitchen waste – cooked and uncooked, layered with some wheatgerm infused with some bacteria to accelerate the fermentation process.

Yes the wheatgerm did seem to keep down the smells and all was well.  My problem is what to do with it after its spent two weeks being filled up and then two weeks sitting.  The pamphlet suggests digging it into the soil.  Problem is the no garden which inspired me to buy it in the first place.

I rang Wicklow Country Council,  (I’m based in Bray).  Unfortunately they have no where one could bring this ‘brown waste’.

So the question is – does anyone know if Dublin County Council have a spot for this?

Or does anyone have any bright suggestions ?

– aside from going into the Woods and digging it in – risking suspicion of body burying or something


 References http://en.wikipedia.org/wiki/Bokashihttp://www.ecoshop.ie/proddetail.asp?prod=1106051658 

George Bush on Global Warming

February 25, 2008

Carbon friendly European travel – to fly or to drive?

February 25, 2008

We’re heading towards Rome next July (from Bray).  We are thinking about driving there with two toddlers in the back seat.  Aside from perhaps it being daft to consign the kids to hours and hours in the car, and us along with them – I’m wondering is it the ‘green’ thing to do?

So I googled Carbon Calculators and came across the one noted below (a)

Its saying 4.5 tonnes for the return trip for the flights.

It is roughly 1890 kilometres
Dublin (Ireland) to Rome (Italy).
Estimated CO2e = 4.5 tonnes.

Comparing it to the driving of 4000 km with a 12Litre/100km petrol 1.4 l car, this other calculator site (b) comes up with 1.1 tonnes.  Now that doesn’t include the ferry footprint. Anyone know where that would come in?    Is it better to landbridge over England from Ireland to France, or ferry to France? 

My litre/100km calculation is based on the figures on my car display (which actually averages my consumption to date on the car at 8L/100km average – I’m just erring on the side of caution)

Is it better to stick to motorways from a carbon point of view? 

Any advise from anyone who has made such a trip before?

Geez, its all questions from me.




Insulation in your home

February 24, 2008

This post is about simple ways to improve insulation in your home.

The plan is to write a load posts on this topic, talking about the specific issues in each case, but this is a short post about simple things you can do to improve the insulation in your home.

In almost all cases, insulating your home is the best place to begin to make significant savings and increase comfort levels in your house. The return on investment is better than any projects to buy more efficient equipment, and vastly superior to any renewable energy. Research has shown that heating represents 50% of household energy consumption, and as improving insulation can help your house retain much of this heat, it can act to reduce the cost significantly. While the energy savings are significant, they are not the only reason for investment in insulation. The increased comfort levels which can be achieved due to improved insulation is a great incentive to action.

Insulating your home

Typical losses and simple measures to reduce them

Typical losses
Simple way to reduce
Roof losses
Adding insulation to a roof space is the simplest of place of all to add insulation. Alternatively any air gaps should be sealed
Wall losses
Install a thin layer of insulation covered by wall paper
Ventilation losses
Keeping your house ventilation is key to good health, however ventilation due to poorly fitted doors and windows may cause drafts. These should be sealed
Window losses
Install heavy, full-size curtains. These provide a partial barrier between the window and the room
Flue losses
At times that the fireplace is not in use, block the chimney (make sure you put a note in the fireplace to unblock it when you light a fire again!)
Floor losses
Install a new carpet, or put underlay under the existing carpet

Spain’s solar tower

February 23, 2008

This is a really cool idea

Microwaves… electricity consumption

February 22, 2008

In one way everyone should have one of these electricity meters… in another way no one should… ever… they make you a complete energy geek. As I made coffee this morning I looked at the microwave, its green display blinked at me… and I thought… yes… I must… so here are the results

I have a 800W sharp microwave, nothing flashy.

Microwave 1

When in standby (just plugged in… waiting) it consumes 3.5 watts of electricity. When heating stuff up at full power (it’s always at full power) it consumes 1250 watts. Now I’d say I use the microwave for an average of 5 minutes a day. So that is 1435 minutes sitting waiting, and 5 minutes of action. So doing the maths bit we find that…

Microwave pie

My microwave consumes 45% of the electricity it consumes, sitting… waiting…

To put this into context, lets assume that there are 2 million microwaves in Ireland (every house, many businesses. Lets assume they are all on standby… all the time… That means that right now, microwaves on standby are consuming 7MW of electricity. If you prefer to think of it as wind turbines. Most of the wind turbines around are 1.5MW machines, and they generate an average of 1/3rd of that. So there are 14 wind turbines needed in Ireland… so we can leave our microwaves sitting… waiting…

So what can I do you might ask? Plug it out, or switch off the socket. Boom. 3watts of electricity eliminated. The clever among you will realise that this rational can be extended to a lot of other electrical equipment around the house, but hold your horses, I’ll get a post out of each one of them yet!

Peak oil… the economics

February 22, 2008

Greennav blog – How is it going

February 20, 2008

So two weeks of obsessively looking at the wordpress stats page, and very happy with what I’ve been seeing, this post is about what topics have been popular, and what has brought visitors to the blog.


Greennav gets a bump


user graph

Following a relatively quiet first few days, the blog got some great bumps when it was mentioned by Eirepreneur, Tom Raftery and Conor O’Neill. WordPress allows you to see what links people have used to find your site, and the lads links have been really helpful… really. It leads me to think a lot about the power of the blog to advertise. In the future, if I put a link to a boiler, or insulation manufacturer or power company, what an effect it could have. It is serious responsibility, and leads me to believe… for the first time ever… that Mulley might have a point… (joke… really… he never has a point!)

On a side note to this I’d like to add a donations to Niall Mellon Township trust button on the side of my page. If some of the more web savvy among you would like to create a button for me (and anyone else who might want it) that would be cool. I mean, shouldn’t everyone have a link like that on their blog.


Search engines really do work


search engine pic

WordPress also gives you the pretty fantastic feature of letting you see what terms people have searched for that found their way to your site, and despite the site only being 2 weeks old, it is doing really well. What is also really interesting is that the search terms. When I wrote the post on boilers… I thought… boring… but on the search engine front… wow…

So what I’m saying is, if you have a non-standard topic to write about… the internet really wants you…


Finally… Comments and other writers

The idea of this site is not for me to write stuff. Come on… I’m a bad writer, and sick of listening to myself. If you have a topic that you would like to write about… please do. Martin has decided to use the site as a way to justify his youtube fetish, that’s fine with me. Any format, any style, that’s fine with me (on green stuff though)