PVC windows V aluminium

nok2008

Hi All,

Just looking into options with regard to windows for a new build and having some difficulty in deciding between PVC windows and aluminium windows. I have got quotes for both and there is a significant difference in price.
I do prefer the look of the aluminuim but is it worth paying nearly 40% more than PVC. The U values for both were roughly the same so guaging them on looks/ quality / maintenance issues.
Anybody have any comments.
Thanks

martinn123

Aluminium windows are in my experience used in Non Domestic situations, Office Blocks, Shopping Centres etc. There will be a considerable difference in price as you have found.

Aluminium, if you are looking at them, should be thermally broken to prevent transfer of cold through the frame.

One benefit is that they can be obtained in any RAL colour, wheras uPVC in primarily, White, Light Oak, Rosewood, Cream, Black, and a few others.

Have you looked at AluClad, they are Timber inside and Alum outside, come well recomended.
I haven't seen any posters here who have used Alum in a new build, but if there are any you may get a few recomendations
Good Luck.

BryanF

martinn123 wrote: »

looked at AluClad, they are Timber inside and Alum outside, come well recomended.

+1

braftery

This might sound obvious but ....

I am sure you have a budget for windows so you need to find the window within your budget that delivers you the best return in the areas you want.

1. Thermal Performance
2. The look of the frame profiles
3. Finishes - RAL, Laminate - Timber Effects, Lacquers
4. Function and design (size and type of openings)
5. Material (Timber, Aluclad, uPVC, Aluminium)
6. Maintainence

Examples;

if Thermal performance is your goal above all else, then passive white uPVC profiles offer the best cost to performance balance.

if you love the timber look but want no maintainence, then Aluclad is probably your best option

In general Aluminium frames are not as thermally effecient as Timber, Aluclad or uPVC. There are new thermally broken Alu frames but if you have large openings make sure that these can be made with the Thermally broken frame as there are size restrictions.

Aluclad windows are a great option as they give you timber interior, no maintainence and low U-Values, but they are probably the most expensive window option in the market today.

.. unless of course you go for bronze clad Oak with gold leaf paint interior which, believe it or not is available !

fclauson

braftery wrote: »

.. unless of course you go for bronze clad Oak with gold leaf paint interior which, believe it or not is available !

ahh - now that is the window I have been looking for - thanks - I'll take 10

Agri contractor

I am building a new house at the moment. I am looking for advice on window choice. We were with Munster joinery last week. They are giving us the prestige model with a 90mil insulated frame. This would have a U value of 1.2. We were with another company today they are offering us a widow with a 64 mil frame and has a 1.4 U value. These are A rated windows. They say the difference between 64 and 90 is minimal, and with a double glaze it leaves in and out the heat more often. A triple glaze takes longer to leave in the heat but holds it inside longer we are told. All our widows are going to be pvc except for one that will be aluminum because of the size. Any help would be greatly appreciated.

braftery

Agri contractor wrote: »

I am building a new house at the moment. I am looking for advice on window choice. We were with Munster joinery last week. They are giving us the prestige model with a 90mil insulated frame. This would have a U value of 1.2. We were with another company today they are offering us a widow with a 64 mil frame and has a 1.4 U value. These are A rated windows. They say the difference between 64 and 90 is minimal, and with a double glaze it leaves in and out the heat more often. A triple glaze takes longer to leave in the heat but holds it inside longer we are told. All our widows are going to be pvc except for one that will be aluminum because of the size. Any help would be greatly appreciated.

In my opinion the letter Ratings (A,B,C etc) are a quite a way behind the curve at this point.

As you described a standard 2G (double glazed) windows using an older spec 64mm frame, which I would consider as the lowest spec window worth looking at) is already achieving the highest rating possible on the scale. This seems to make the entire scale redundant !!

The difference between a 64mm frame and a 90mm frame can be very significant .. it is also worrying that a 90mm frame is only achieving a rating of 1.2Wm2k ... Usually frames of this section size should be getting a window down to at least 1.0Wm2k.

You mention one large aluminium window, what is the U-Value of this window ? As it is large it can end up being a big heat soak in a space. It would be well worth looking at alternatives (Aluclad, uPVC facade, etc)

I am attaching a chart (which I did not personally produce, but found on the net and is part of a larger presentation about window U-Values) that should help people understand the heat gains and losses by various glass package types, however it is important to see windows as part of the overall building package.

It is not just about heat gains and losses, 3G (Triple Glazing) does have a lower solar factor and therefore gives a smaller heat gain, but its most important quality and that of more effecient frames is to give you Heat Stability.

Generally we are now building thermally effecient and air tight Buildings. Once these buildings are at their optimum temperature they do not lose this heat easily. It is therefore important to keep the temperature stable.

Large solar gains in strong sunlight can make rooms uncomfortably warm and require venting by either opening windows (losing this energy back into nature) or use of a HRV system (which uses electricity !) to transfer the heat to another part of the building.

3G glass lets less heat in or out, therefore reducing both gains and losses, creating more stability in the building temperature and requires less venting or transfer of heat.

It is quite common now for people to talk about getting 3G on the north face of the building and 2G on the south face. Unless you get proper calculations worked out for this idea I think it can have no gain or sometimes be detrimental to the living quality in a building.

I hope all of the above helps you in your decision making process

nok2008

Hi whilst that chart is useful i would like to see another line in the chart which would be the rough net costs / benefits of going triple glaze versus double glaze.
Everybody states that you save money but nobody can say how much i.e. say 3G is €5K extra for the windows in a new build. How many oil tanks could you fill for €5K. Also if you went 2G and invested the €5K in extra insulatation in the walls what would be the benefit.

braftery

nok2008 wrote: »

Hi whilst that chart is useful i would like to see another line in the chart which would be the rough net costs / benefits of going triple glaze versus double glaze.
Everybody states that you save money but nobody can say how much i.e. say 3G is €5K extra for the windows in a new build. How many oil tanks could you fill for €5K. Also if you went 2G and invested the €5K in extra insulatation in the walls what would be the benefit.

Any company that is charging you more than approx €30/sq mtr of window more for 3G is ripping you off. This figure allows for toughened 3G glass etc. So unless you have pretty unusual glass package requirements you should be able to use it as a guide.

I am not sure how big your job is but the average job in ireland is between 50 to 75 sqr mtrs ... so including VAT this should not add more than between €1700 and €2500 to a job.

However, your point about using money more effeciently is well made.

It is critical to see the building as a whole and always consider the finished product.

Personally I think one of the best ways to spend money like this would be to get someone to prepare well thought out details for the junctions and integration of all the very thermally effecient products being installed into buildings. Unfortunately, in my experience, this is an area where money is rarely spent, leading to buildings full of great components that are poorly put together.

BryanF

nok2008 wrote: »

Hi whilst that chart is useful i would like to see another line in the chart which would be the rough net costs / benefits of going triple glaze versus double glaze.
Everybody states that you save money but nobody can say how much i.e. say 3G is €5K extra for the windows in a new build. How many oil tanks could you fill for €5K. Also if you went 2G and invested the €5K in extra insulatation in the walls what would be the benefit.

if everybody house was exactly the same then this would be a simple cost calc but all house are differnt so do a PHPP calculation and this will answer this and a host of other issues that will arise during the build

+1 with braftery

Agri contractor

I am probably going to get my windows from Munster joinery. The are slightly cheaper than the other companies and I am getting allot more extras than the 60 mil windows the other companies are pricing me for. I am putting 90mil double glaze on all the south facing. U value of 1.2. Triple glaze on the back with a u value of .8. I have one large sliding door which will be done in aluminum this will be done in triple glaze and the best u value I can get on this is 1.6

braftery

Agri contractor wrote: »

I am probably going to get my windows from Munster joinery. The are slightly cheaper than the other companies and I am getting allot more extras than the 60 mil windows the other companies are pricing me for. I am putting 90mil double glaze on all the south facing. U value of 1.2. Triple glaze on the back with a u value of .8. I have one large sliding door which will be done in aluminum this will be done in triple glaze and the best u value I can get on this is 1.6

Out of curiosity .. are Munster Joinery giving you a breakdown of the actual U-Value of each of your windows or are they simply quoting you the U-Value for the window range, based on the test window (1230 x 1480) for that range ?

Also it would be interesting to know what sqr meterage of each window type by u-value you have to work out an average for your project, as i suspect the big sliding door will make a big dent in the overall U-Value rating of your glazing package.

Agri contractor

they are giving me a u value on each window including the frame. What I am confused about, Munster joinery are using a 90 mil insulated frame double glazed window. Other manufactures are using a 60mil frame that is not insulated and they still claim they can achieve a u value of 1.2.

braftery

Agri contractor wrote: »

they are giving me a u value on each window including the frame. What I am confused about, Munster joinery are using a 90 mil insulated frame double glazed window. Other manufactures are using a 60mil frame that is not insulated and they still claim they can achieve a u value of 1.2.

The U-Value of the frame is determined not only by the section thickness but also by the number of chambers in the PVC profile.

Most window manufacturers are using uPVC profiles from one of the big profile suppliers, Profine, Veka, Rehau .. I am not sure about MJ but they might be making their own.

The U-Value of the window is the combination of the U-Value of the glass package, U Value of the frame profile, the glazing spacers, the profile face widths, the seal lengths, etc ... There are multiple ways to get to the same U-Value for the overall window.

This is the formula to determine the U-Value of any window.

Uw = (Af*Uf+Ag*Ug+Lg+PSIg+Le*PSIe)/(Ag+Af)

Af = Frame Area
Uf = Frame U-Value
Ag = Glazing Area
Ug = Glass U-Value
Lg = Length of Glass Perimeter
PSIg = Thermal Value of Edge Spacer
Le = Length of Seals
PSIe = Thermal value of Seals

For doors you need to calculate the Uvalues for the Threshold part of the frame and average it as a percentage of the overall surrounding frame. The door design will also alter the frame areas and if you use panels you will have multiple glass areas and u-values to determine.

This all makes the calcs for doors alot more complex.

How does the sq meterage to U-Value on our job work out ?

braftery

If there is only a small difference in the pric, one question to ask all of the window companies that quoted for you job is what is included in the installation from them.

I know some companies, will install the windows and put insulating foam around the windows and this is included in the overall price, I also know that some companies to not do this work, leaving you with an additional expense of doing it yourself.

This might seem small but good quality foam (which is essential) and the time needed to do the job properly would probably amount to a few hundred euro, depending on the size of your job.

Agri contractor

Thanks for your posts braftery. Munster joinery don't put foam around the windows they told me. The builder says he is doing that work.

BryanF

Agri contractor wrote: »

Thanks for your posts braftery. Munster joinery don't put foam around the windows they told me. The builder says he is doing that work.

mj have/offer details of how their windows should/can be installed. I'd suggest you show them to your builder/architect

howa .223

braftery wrote: »

If there is only a small difference in the pric, one question to ask all of the window companies that quoted for you job is what is included in the installation from them.

I know some companies, will install the windows and put insulating foam around the windows and this is included in the overall price, I also know that some companies to not do this work, leaving you with an additional expense of doing it yourself.

This might seem small but good quality foam (which is essential) and the time needed to do the job properly would probably amount to a few hundred euro, depending on the size of your job.

just too add dont buy the can with little tube you cant rightly control the foam beast buy a foam gun approx 40euro but you can control the amount of foam needed and wont have much waste if any