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4 essentials for successful window specification

22 December 2022

When it comes to the effective specification, design and installation of windows, several key factors need to be carefully considered. Here’s our guide.


With decades of experience working with architects, specifiers, contractors and fabricators, the same considerations come up time and again when it comes to window specification.


Delivering an efficient, cost effective, high performing window and door solution relies on understanding four key issues:


1. Thermal performance and ventilation
To ensure comfortable living and working experiences in buildings, consider two things:

  • The required thermal performance of windows
  • The necessary ventilation in occupied spaces

When thinking about the necessary U-value of solutions to prevent heat loss, specifiers must also consider the effect on the G-value of the glazing to be specified (which measures how much heat is likely to enter the building as a result of solar heat gain). The balancing act between heat loss and space overheating is important when it comes to the long-term effectiveness of the scheme.  This is growing in importance as the Future Homes Standard looks to tighten the regulations around thermal performance of buildings.


Likewise, ventilation requirements must be carefully considered. The Future Homes Standard lays down specific criteria concerning the amount of ventilation required for living spaces, and this significantly impacts the types and sizes of final window and door specification. 


Solutions for medium or high-rise developments must consider critical safety aspects and design in window solutions that are safe to use at high levels, as well as provide the ventilation demanded by occupants. Questions around natural or mechanical ventilation will influence specification choice too, with the need to avoid moisture or stale air build up.


2. Design, finish and acoustics
Chief among the consideration points for windows will be the choice of colour and style to enhance the aesthetics and visual appeal of the building.

  • Is a white or coloured foil finish required?
  • What about the joints? (Stainless steel fixings are needed in coastal environments)
  • Who will be cleaning the windows? Occupants (tilt-and-turn or reversible windows) or external cleaners (value engineered window designs)?

With brownfield sites and urban locations prone to noise pollution from roads and rail lines, the acoustic performance of the window must also be a top priority. 


Again, existing regulations are clamping down on residual noise level acceptance and forcing specifiers to satisfy ever tighter criteria. But the noise reduction requirements between low- and high-level dwellings are markedly different and need to be factored into development planning, where disparate needs may enable specific product choice flexibility and potential cost reduction.


Finally, linked to the U- and G-value considerations, the weight of glass and glazed units must be noted. Can the system take the weight of glass specified to meet thermal, ventilation and acoustic demands?


3. Installation
When it comes to installation, the specification decision process needs to cover several key areas. This includes assessing the wind load on the development and whether the window solution can satisfactorily deliver the performance needed when exposed to the elements.


A focus on the style of building also underscores specification decision making.

  • Is it a concrete frame or brick and block style of construction?
  • Do the windows require direct fixing or fixing with straps?#
  • What is the interface detail and the sought-after external finish?
  • Do the windows work seamlessly with the desired aesthetic look of the façade?

Assurances should be sought around meeting the on-site programme scheduling for installation. Products such as aluminium frames often have longer lead times than PVC-U and specifiers should ensure the manufacturing and installation supply chain can meet their timescales. If not, switching specification can open the opportunity to accelerate completion and meet pressures to deliver a finished development.


4. Safety and security
Safety and security aspects are vital for window specification. In settings such as care homes, for example, you may need to provide restrictive use so potentially vulnerable residents are not exposed to dangers around window openings.


Accreditation is also important, and the specification team needs to be clear about the standards to which the final scheme must adhere. The rigorous use of testing must be factored in, and this can range from on-site water testing that underpins wind, weather, and security aspects, to ensuring all current regulations are satisfied across a range of criteria.


The successful specification of windows and doors forms an integral part of the overall scheme and requires a detailed assessment of many important areas ahead of any final decisions. 


Our in-depth experience of working alongside specification teams helps us guide them through what can be challenging technical, regulatory, design, and installation stages. For help with your specifications, call 0300 333 6525 today.