How to prevent heat loss in the home

Domestic and Commercial Glazing Manufacturer, Supplier and Installer

How to prevent heat loss in the home

A very big problem is faced currently in the home with ever  rising heating costs, which only seem to get worse with each year.  The best option is for the homeowner to tackle the root of the problem and that is HEAT LOSS.  Where is the heat escaping and how to minimize it.

It is safe to say that this is an ongoing problem for many people and there are no quick fixes that will provide lasting solutions.  How to prevent heat loss in the home continues to perplex us.

A big contender for heat loss are old inefficient windows, single glazing or really any kind of non thermally broken window frames.  Ask the question of do the windows need replacing or can you patch the problem?

This is a ‘How to’ guide on the benefits of double glazing

What you need to know and how to prevent the costly pitfalls of replacing whole windows when not necessary.

What are the benefits and how to use double glazing for preventing heat loss.


Firstly, just what are the benefits of double glazing?

:         Up to 18% of heat lost on not having double glazing, resulting in increased bills, higher Co2 emissions, more condensation, and higher noise levels so there are many advantages to double glazing.

:         Double glazing consists of two panes of glass sandwiched with argon gas which acts as insulator of heat and noise. Condensation occurs with single glass windows because internal air reaches its dew point and deposits water on the coldest object which will be the windows.

:         Double glazing is a longer term investment which will create a warm and quiet environment as well as been aesthetically pleasing.

form 1

Heat loss in the home


First Steps when choosing to have double glazing

  1. Look for double glazing companies that have testimonials from satisfied customers on their websites or by word of mouth, as the internet can be a bit of a mine field.
  2. Go on to the FENSA web site which is set up by the Double Glazing Industry for homeowners and here you can look up a reputable company.
  3. Supplier will come out and have a discussion and look at the windows to give a estimate for the costs.
  4. Surveyor will then come out and accurately  measure the windows and doors, and ask what openers are needed on each window, what style,  what type handle chrome, white or gold, type of glass for bathroom as needs to be obscure, and if having a composite from door or aluminium . A lot of questions!
  5. Fitting for average sized house usually takes 4 days.
  6. Curtains taken down and dust sheets put over carpets.
  7. Price on average £5,500 including doors etc. for an averagel 3 bed home
  8. Speak to your glazing company about anything special you need to achieve, external noise reduction can be achieved with options such as triple glazing, different glass thicknesses on each pane, whereas more thermal efficiency can be achieved with a thermally broken glazing bar and/or a wider air space and argon gas between the glass panes.  These options can help with preventing heat loss.


Windows before and after double glazing


installing new glazing

Step by step of removal of old windows

new glazing

Before and after new glazing

Does it need replacing?

Most people think that a broken or condensation-filled double glazing unit means that the whole frame will need to be replaced with a brand new unit. However, that’s not always the case.

In some cases all that is needed is a new pane of glass, which will work out much cheaper. In order to replace the glass, you’ll need to know whether your window is internally or externally beaded. Examine the frame and check where the beads meet the inside of the frame, identifying whether there is a join. – Quoted from GRP Designs


Fitting window yourself

It’s relatively simple to replace a pane of glass, however, undertaking this job should only be done by those competent (and confident) enough to do it. Get an expert in to remove and replace the glass window if you’re unsure in any way, or if you don’t have the full set of tools to do it.

Example of double glazed window with condensation


misted glazed unit

How to spot a broken down double glazed unit

  Example of a misted unit

uPVC, wood or aluminium

uPVC is used for double glazed windows, this is a very safe and stable. It comes in wide range of finishes. uPVC has almost replaced cast iron in construction  uses, which was used for drain pipes and guttering on houses.

uPVC is used for window frames due to it resistance against sunlight and rain, as well as being resistant against chemical.  It does not decompose or rot and is very difficult to break. It retains its shape in normal climate and is therefore ideal for window installations.

Alternative frames are timber made from varieties of hardwood.  Durable and attractive they give homes a traditional look.  They do require dedicated maintenance and are expensive. Usually they should be stained or varnished rather than painted.

When purchasing timber frames make sure the wood has been properly dried to avoid problems of cracking or shrinking.

Another alternative is Aluminium double glazing window frames  which were popular in the 60’s and 70’s but are  now less widely used due to their relatively high cost and poor insulation.  When aluminium is used, a thermal break between the frame and double glazing window will help the window’s energy rating. They are suitable for situations with strong sunlight or very wet conditions.


New Window Requirements

A window should ideally offer the following:

üBe easy to maintain and clean
üLet in a lot of light
üLook good and be aesthetically in-keeping with your home
ü Be highly secure with the locks etc
üHave glass that can’t be removed from outside
ü Have a high energy rating (A++ is currently the highest) to reduce energy bills
üBe made-to-measure
üKeep out draughts
üNot more or shake when it is windy
üLong lasting guarantees



Fitting a double glazed window

Double-glazing generally comes in three parts, the frames, the sill and the glass. When you order, they will arrive separately with the beads in the frame so you can pretty much see how the glazing beads fit in.

Remove your existing windows carefully. The less mess you make of the walls the less work you will have to do later on. Check you have not damaged any vertical damp proof courses or that they have not pulled out with the old frame. If they have, slide them, or new lengths, back into position. .


Most modern windows come with trickle vents in the top section of the frame. These vents allow warm air that has built up in the window recess, to flow out rather than hitting the cold glass or frame and condensing

Trickle vent

Trickle vent example

Trickle vent for double glazed window

Frames and Beads

Sealed units (the glass) are two panes of glass kept apart by a coloured spacer bar (mostly silver or brown). This is filled with silica crystals. These crystals soak up the moisture to keep the air gap between the panes clear. You should be given a 10-year guarantee on these units. The glass will be cut to fit the frame you order so you only have to worry about getting the right size frame. The glass will also be cut to allow room for the heads of the frame fixing screws at the side of it.


Window frame

New window frame with beading and trickle vent

Upvc window and beads

When you insert the glass you will need to space it out so the borders are equidistant in the frame. In the case of a “barred” unit, which is a sealed unit with inbuilt glazing bars to make it look as if it is lots of small sections, you will need to make sure the glazing bars look absolutely horizontal and vertical. This can also be done using the spacers.

The beads, if installed when you take delivery of the frame, can be removed using a sharp scraper or chisel, this will give you a clear view of the rebates that will receive the glass.

Window Sill and End Caps

The frame will come separately to the sill and the sill will probably have to be cut to length on site as normally you get a little extra to play with. The sill in most cases will also come with some end caps which need to be glued on to each end of the sill with a special PVC superglue. Occasionally the sill and window will come with the glue but in most instances you will have to purchase this separately. The glue can be purchased from most window and glazing suppliers.

The sill sits on the top of the outside skin of the wall, on a mastic, or sand and cement bed. A bead of silicone is applied to the top of the sill and the frame then sits on that. The back edge of the sill will have a little upstand against which the window will butt and this is where you put the silicone. Do not seal the gap which will be between the bottom front edge of the window frame and the top of the sill. There are drainage holes in the bottom of the frame and any water that does get into the frame can run out of these holes and run off the sill.

window cill and end cap

Window cills

Window sill and End Cap


drain holes

Drain holes




Drain holes, DrainGap and Pvc glue.


Drain hole cap

Drain holes cap

Types of different thickness spacers

The fixing holes are drilled once the beads are out and the screw heads are covered by the sealed unit when it is placed in the frame.

Put the frame in and square it up within the opening using the plastic spacers. You can ask to have a variety of spacers sent with the windows you order.

Choose a solid area of wall and drill through the frame and wall. Countersink the fixing hole gently, the pvc section here is not very thick and you just want to be able to lose some of the heel of the fixing.

Insert the correct length “frame fix” screws, which come complete with plug. Take the screw from the plug and push the plug in first, (you may have to give the plug some help to get it through the frame and firmly into the hole in the wall) then push the screw in as far as you can by hand, then tap it in a bit further with a hammer and finish it off with the battery screwdriver.


Try and get your fixings either near the spacers you have used, or in positions where the frame is touching the reveal. This will make sure you do not bow the frame when you tighten up. With opening windows the fixing goes in the rebate that does not foul the closing of the window.


Drilling and fixing window frame

Window fixing

Window fixing

Countersinking screw heads into window frame


Countersink screws

Place the glass square in the frame, using spacers to ensure it is square.


As you can see double glazing enhances your home and has many benefits including saving you money on heating bills, etc.  Obviously having several windows replaced would be best being installed by a professional fitter.

 An Example of Different Styles of windows  – Everest


window example everest

Window Example

Double glazing done by a Glazing company

 Tips on when Double Glazing fitters arrive to fit windows

Some are day labourers who are not accountable to the contractor, though very rare things get stolen.

  1. Remove any breakable items from their work area.
  2. Create goodwill by being polite.
  3. When you need to communicate talk to the leader if you have any concerns.
  4. Don’t hover but be around within earshot.


What window installers should check for when finished?

  1. When doors are slammed there should be no movement in the mullion or outer frames,
  2. Are windows fitted square upright and plumb
  3. Are the exposed parts undamaged.
  4. Take your time to inspect windows once they are fitted to see if any scratches etc.

Guarantees  and payment

It is best to discuss with your double glazing firm as to what options you can pay by.   You can either start making payments at a future date.  Some companies might offer interest free payments.  Make sure you read the terms of the payment terms.  Another way to pay is in stages, when one lot of work is finished you pay.  You do not have to pay for work that has not been done so it would be best to keep invoices and receipts.

A glazing company will usually ask for 20% to 30% deposit, be careful about this though because if the company were to go bust it would be difficult getting your deposit back. If possible use a credit card because this way it is easier to get a refund from your credit card issuer should the company go bankrupt.  This being said it is best to go for a reputable company that wouldn’t go bust!!


Under the Supply of Goods and Services Act 1982 you are provided with certain rights as a consumer.  If the job of the installation of the double glazing is not done to a satisfactory standard then you have certain rights.   It is important not to sign a note saying you are satisfied with the job as this could harm your case should you seek to gain damages.

Some double glaziers will offer a guarantee on their work.  Read the small print because once you have signed as it is a legal document will be legally binding.

In some cases you may be able to cancel a contract provided it is done within 7 days of signing the contract which includes a customer cancellation contract. Keep all copies and make sure the company receive your request within 7 days.



Finished Product


Once your windows have been fitted you should be pleased with the overall affect, it should be ascetically pleasing, no noise or condensation, a quiet environment, all in all a job well done. › Double Glazing