Can you estimate (approx) the amount of savings from upgrading your windows?

andybookie

I have just bought a house and deciding where to prioritise spend.
We need the back windows replacing as the wood frames are rotten.

I would like to build a case to get both the back and the front replaced.

It's roughly an extra €2k for the front windows.

Could you approximate that the savings made on a heating bills over the year would be XX amount?

The current windows are double glazed but thin and rickety old wooden frames.
New windows would be far more efficient PVC double glazed, A grade windows.

I know it is depends on current efficiency and quality of windows, but if the consensus is €200 a year then I could offset that in my mind.

Lumen

Short version: if your window frames are falling apart you should replace them.

Long version...

It's difficult to estimate without knowing what area of windows you have and what temperature you want to maintain in the house.

When I did my back-of-fag-packet estimations of where my 4k a year in oil was going, I got these numbers:

Uninsulated cavity wall: 33%
Windows and doors: 25%
Roof/attic: 30%
Uninsulated floor: 12%

The problem with those calculations is that they're based on conduction losses from a well sealed structure, and my crap house is very leaky. In fact, according to the calculations I should only need a small boiler, and even though I overspecced the boiler it still has to run at full tilt to keep up with the heating losses (as you'd imagine from my oil bill). So, air tightness is really important. As I've started ripping the house apart bit by bit I see a lot of holes and leaky areas which I'm addressing bit by bit.

The point I'm making is that while good windows are important, you may also have problems elsewhere. So you might want to get a proper heat loss survey done, including blower door test, to figure out what to prioritize. That's more money.

BryanF

is cost the only consideration ? What about comfort ?

Wartburg

andybookie wrote: »

New windows would be far more efficient PVC double glazed, A grade windows.

Far more efficient only for the case of an appropriate installation including complete insulation and air tight layer around the window frame. Banged in too tight and sealed with traces of mastic could lead to a similar performance like the existing ones.

andybookie

BryanF wrote: »

is cost the only consideration ? What about comfort ?

Fair point

andybookie

Lumen wrote: »

Short version: if your window frames are falling apart you should replace them.

Long version...

It's difficult to estimate without knowing what area of windows you have and what temperature you want to maintain in the house.

When I did my back-of-fag-packet estimations of where my 4k a year in oil was going, I got these numbers:

Uninsulated cavity wall: 33%
Windows and doors: 25%
Roof/attic: 30%
Uninsulated floor: 12%

The problem with those calculations is that they're based on conduction losses from a well sealed structure, and my crap house is very leaky. In fact, according to the calculations I should only need a small boiler, and even though I overspecced the boiler it still has to run at full tilt to keep up with the heating losses (as you'd imagine from my oil bill). So, air tightness is really important. As I've started ripping the house apart bit by bit I see a lot of holes and leaky areas which I'm addressing bit by bit.

The point I'm making is that while good windows are important, you may also have problems elsewhere. So you might want to get a proper heat loss survey done, including blower door test, to figure out what to prioritize. That's more money.

Thanks, very thorough.
I am making the following argument for replacing the windows.

• Saving on monthly energy bills.
• The convenience of getting everything done at the same time (we are currently renovating all the house)
• Saving on painting the frames inside and out.
• Comfort of a warm house (both front and back).
• Noise reduction
• Saving on insulation strips if we kept the old windows (minimal but still)
• Safety - new windows would be safer for break ins.
• Increase the value of the home.

I estimate that we would make a saving of around €200pa in energy bills and the windows would pay back themselves in 8 years.