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What are Double Hung Sash Windows?

Posted: 25 January 2024

Sash windows have been popular in homes and businesses since the 17th century. They have two panels, and typically, one is fixed and the other slides vertically to open. With double hung sash windows, both panels can be moved, so the window can be opened by either sliding the top sash down or the lower sash up.

The invention of the double hung sash window is usually credited to Robert Hooke, the scientist, architect and astronomer who served as chief assistant to Sir Christopher Wren in the late 17th century. Double hung sash windows are as popular today as they were in the Georgian, Victorian and Edwardian eras. 

Advantages of Double Hung Sash Windows 

The option to open either or both sashes brings several advantages, including the following: 

  • Enhanced ventilation options and easy-to-control airflow into and out of the room
  • Easier to clean exterior outer panes from the inside – no need to use a ladder
  • Safer for households with small children – opening the upper sash allows ventilation without the risk of them coming into harm 

Disadvantages of Double Hung Sash Windows

With older installations that have been in place for decades or even centuries, double-hung sash windows can be draughty. With box mechanisms for each sash, there is also more to go wrong in terms of sticking pulleys or damaged cords. However, modern sash windows are highly energy efficient and require minimal maintenance, so these are no longer concerns with new double hung sash windows.

Similarly, owners might have justifiable concerns about the security of period sash windows. However, modern double hung windows meet all the latest security standards.

Safety and Security of Double Hung Sash Windows

As already mentioned, double hung sash windows make it safer to ventilate a room when there are small children around by opening only the top sash and leaving the lower one secure. For the same reason, they are useful in other environments where there are potentially vulnerable people, such as schools, hospitals and care homes.

Modern sash windows are also highly secure from an intruder prevention perspective. Lomax + Wood double hung sash windows have been extensively tested by BMTRADA and meet the Pas 24 Security standard.

Internal View of Double Hung Sash Windows

Energy Efficiency of Double Hung Sash Windows

While original double hung sash windows can be draughty, modern ones are highly energy efficient, keeping the warmth in and the draughts out. Installing new double hung sash windows doesn’t just make a home more comfortable for the inhabitants. It can also significantly reduce a home’s heating and cooling costs. The latest double hung sash windows from Lomax and Wood raised the bar in terms of thermal efficiency with a U-value of 1.1 W/m²K f. This exceeds even the stringent new regulations set forth in the new Building Regulations for 2024.

FAQ in Relation to Double Hung Sash Windows

1) Do Lomax + Wood install many double hung sash windows?

Yes, double hung sash windows are very popular as they provide the optimum ventilation options while meeting industry standards in terms of security and energy efficiency.

2) What is the difference between a sash window and a double-hung window?

A single sash window has one sash that is fixed in place while the other opens vertically. With a double hung window, both upper and lower sashes can be opened.

3) Why would someone choose a double-hung window?

Double-hung windows offer superior ventilation by allowing hot air to escape when the top sash is lowered. They also make it easier and safer to clean windows, as they can be cleaned from the inside.

4) Are double hung windows more likely to stick?

Modern double hung sash windows are simple and smooth to operate. They will give decades of reliable service as long as they are kept clean and given periodic lubrication.

5) Are double-hung windows draughty?

In period properties, original Georgian or Victorian double hung sash windows can be draughty. However, today’s sash windows meet the most stringent energy efficiency standards.

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