NEW WINDOWS: double glazed is now the standard

Buying a traditional single glazed casement or sash window is now effectively impossible. The standard is now double glazed and placing an order for a custom made unit is the only way you will get a traditional single glazed window. That is.... if you are allowed to install one!
This is the direct result of changes in building regulations introduced in 2002 and revised in 2006. These came about following the Kyoto agreement where the UK Government made commitments to reduce emissions of greenhouse gases.
Document L is the section of Building Regulations for England and Wales which sets out standards of energy efficiency in buildings. The new Document L now comprises two separate sections: L1 (L1A refers to new dwellings and L1B to existing ones) and L2 (relating to non-dwellings).

As more energy efficient buildings help to reduce pollution and preserve dwindling natural fuel resources it is now a requirement that more energy efficient building products are used both in the construction of new houses and the refurbishment of existing ones. Windows are clearly weak points as they allow heat to escape and cold air to enter if not appropriately sealed and - now - double glazed.
However, where refurbishment work and improvements on existing dwellings are concerned there are a number situations which may be considered exceptions and in which the use of single glazed windows may therefore be allowed. This would for instance be appropriate on front elevations of listed buildings where only a limited number of units were being replaced. However identical the new timber frames may be to the original ones, double glazing causes light to reflect in such a way that will always highlight the increased depth and the presence of a sealed glazed unit.
Whether your planned refurbishment qualifies as an exception is something you or your designer need to determine before you reflect on the aesthetic and practical merits of single versus double glazing.

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From Building Construction Handbook

(6th Edition) by Roger Greeno

SASH WINDOWS: sound insulation possible?

If traditional sash windows are the only barrier between us and London traffic we might be able to tackle the problem simply by improving or installing draught seals. As well as draughts, these seals also reduce airborne noises which find their way through the smallest and least noticeable gap.
If the problem persists one might be tempted to consider secondary glazing. Effective as this solution may be, the “aesthetic” compromises it implies often mean it is not a viable solution. If secondary glazing is not an option the sash window glazing needs to be addressed. This will need to be upgraded to a “sealed unit”, i.e. two sheets of glass sealed on all fours sides and installed, in the case of sash windows, within the sash bars. One of the sheets of glass used is often an acoustic glass. There are many types of acoustic glass, available in various thicknesses (4.4mm to 12.8mm in terms of window glazing) and designed to control various levels and types of noise. Developed and tested by the larger glass manufacturers (e.g. Pilkington Glass) the results are often not as impressive in real life situations as they may be on paper. Noise travels in waves on varying frequencies. Sound insulating materials attempt to control noise by disrupting the flow of these waves. Every time the wave passes through a barrier it is diminished and the shape of the wave is altered. Acoustic (laminated) glass is comprised of 2 or more layers, laminated together with a special film separating the layers. As the sound wave passes through each layer it is diminished: the thicker the sheet the more effective in breaking down the sound.
Here comes the inevitable compromise: as the glass gets thicker it also becomes heavier and so the weights used to raise the traditional box sash window will have to be increased accordingly. More weights will result in less room to move within the box itself and the window will therefore become less functional: the weights will have nowhere to slide and one of the sashes will effectively become fixed.
The “art” of compromise is therefore based on understanding. Sound insulation is probably best achieved via well fitted windows with good draught strips, laminated safety glass 4.4mm or 6.4 mm thick may not be quite as acoustically efficient as the best specialist glass but, at a fraction of the price, it will dramatically assist in an overall noise reduction plan.

DOORS & WINDOWS: back to basics

Successful interior design needs to be based on the "skin and bones" of a house. The structure, fixtures and fittings are often left unquestioned. These subconsciously but immediately inform our initial perception of our surroundings. On a more practical level, a hollow poorly fitted door provides little sound insulation just as an inexpensive or badly maintained window causes the same problem as well as allowing heat loss.
I work mainly on listed buildings and properties within conservation areas where the replacement of windows usually has to be implemented on a strictly like-for-like basis (i.e. timber for timber, sash for sash, with allowances made for modern sealed glazing units). There are many firms out there offering the benefits of sealed glazed units applied to traditional timber window designs. Having spotted their "conservation range" I recently contacted Mumford & Wood who are assisting me with the planned replacement of Georgian style sash windows. I will post once "before & after" comparisons are available.

Where doors are concerned there is often more scope for choice as the rules are somewhat less stringent (in non-listed buildings of course). In an ideal world no expense would be spared. If the budget allows for this I would not hesitate in contacting Longden whose doors grace many of the top developments in central London.
Should the budget only stretch as far as an improvement, I would at least consider solid paneled doors, oak if possible (in spite of the tradition for pine where painted doors are being specified). As always, when savings have to be made, one's understanding of doors will be tested far more than it would be if the made-to-measure route were an option:
1. the sizes of existing door openings will dictate whether standard sizes will fit;
2. some doors will more than likely have to be fire rated and sourcing these to match the style of the non rated doors is not quite as easy as it sounds;
3. as a result a combination of made-to-measure and standard sizes often ends up being the only possible way forward.

So what do all these different types of doors cost?
One shortcut to the answer is provided by this table available on the GreenSpec web site. The purpose of the table is to assess the cost of each type of door and its maintenance over a 60 year period and therefore needs to beread with its scope in mind. The background research provides however, at the time of writing, a good indication of how much each door will cost you (although fitting and decorating costs have probably undoubtedly increased since).