Slim double glazing to match your existing sashes

With the steep rise in energy costs – and bills forecast to hit over £4,200 a year – homeowners are looking for new ways to keep their property warmer this winter. If your home has traditional timber sash windows with original single glazing, you may find that you struggle to keep the heat in and dread your energy bills spiralling. So what’s the solution?

At Ventrolla, our timber sash windows are crafted to protect prized Georgian, Victorian, and Edwardian architectural heritage from the ravages of time. But our windows also meet the demands of today’s lifestyles. It’s thanks to our unique blend of time-honoured joinery skills and future-proof technology, that we can ensure wooden sash windows retain their heritage character while offering homeowners the benefit of modern home comforts.


Our sash windows can be made to incorporate the right glazing for your home – from efficient slimline double glazing and conservation-friendly secondary glazing to single glazing to suit the most restricted locations. But for now, let’s look in more detail at our slim double glazing.

How does slim double glass glazing work?

New bespoke sash windows can be crafted that match your existing sashes, and preserve your home’s historical  integrity. Energy efficient slim double glazed units will be installed into them along with our innovative hidden draught proofing system (the Ventrolla Perimeter Sealing System), that has been tested to withstand winds up to 71 mph (a category 1 Hurricane starts at 74mph).

These handcrafted sashes are then placed back into the original box frame leaving you with beautiful, unique timber sash windows that are full of charm and have all the modern benefits a upvc imitation would bring.


The spec in more detail

  • Slim 16mm (4/8/4) double glazed units
  • Planitherm Total+ glass (outer pane) and krypton filled cavity
  • Centre Pane U-Value of 1.2 Wm²K
  • Total Window U-Value of 1.5 Wm²K

Our slim double glazing measures just 16mm. We use Planitherm Total + glass for the outer pane – a high-performance, thermally insulating Low-E glass, that has been designed to help windows meet the highest Window Energy Ratings (WERs). The cavity between the panes is filled with Krypton – an inert gas that has a lower thermal conductivity than air, so this not only keeps your home warmer but also gives your window a lower acoustic conductivity, for better sound insulation.


The glazing we use benefits your home by giving your window a better ‘U’ value—this is a measure of thermal insulation. The lower the ‘U’ value, the greater the performance in terms of how much energy is required to maintain a comfortable temperature within a property. You can read more about U ratings and energy efficiency on the Energy Saving Trust’s website.

So if you would like to arrange a free, no-obligation consultation with our team to look at providing your windows with new slim double glazed sash window units, don’t hesitate to get in touch today.