Choosing windows for a new build

The most common factors that affect the choice of windows are:

  1. Planning Permission

  2. Building Regulations

  3. Type of Glazing to achieve Energy Efficiency

  4. Style/Frames/Cost


1. Planning Permission:

The planning permission conditions will outline any restrictions imposed on your building project.  In general, restrictions are not imposed on the type and style of windows to be used within the building project, unless however you are building in a conservation area where restrictions may be imposed on the type/style/colour etc. of the windows used.


2. Building Regulations:

A U-Value is the measure of the rate at which heat is lost through the Building Fabric, so the lower the U-Value the better.  A window with a lower U-Value gives a better energy rating.

Unlike walls, floors and roofs, windows are strongly affected by solar radiation and airflow around them.  Therefore, the window manufacturers measure the window U-Value by taking into consideration the glazing U-Value and the frame U-Value to calculate the overall window U-Value.

The Chosen windows should have a U-Value to meet the requirements of the current Building Regulations. Please see below Table 1 from TGD Part L 2011 outlining the maximum U-Values permitted for each element when building a house.



3. Type of Glazing to achieve Energy Efficiency:

There are numerous different glazing options to choose from in todays’ market.  But, it all comes back to U-Values and energy efficiency.  The lower the U-Value the more energy efficient the window is.  A number of items affect the U-Value of a window, these include but are not limited to:

  • Number of panes – Double or triple glazing
  • Type of glass selected – non coated/ low E coated (hard or soft)
  • Type of filling between glazing sections – air filled/argon gas filled
  • Thickness of gap between glazing sections etc.


4. Style/Frames/Cost

Planning restrictions aside, the chosen window style and frame type will all come down to personal preference and budget.  The two most popular window styles in Ireland are Casement and Sliding Sash with the latter being the more expensive option.

Below is a list of the majority of window types available in today’s market, outlining the approximate costs per m2 (inclusive of VAT) for each type.  The cost of the windows varies on many factors, most of which are outlined in the paragraph above.


  • Windows with UPVC frames – approx. €130-€275/m2
  • Windows with Nordic/Scandanavian Pine frames – approx. €300-€340/m2
  • Windows with Aluminium frames – approx. €310–€440/m2
  • Windows with Composite Timber/Aluminium frames – approx. €370-€455/m2
  • Windows with Hardwood/Engineered Timber frames – approx. €400-€490/m2 & approx. €580/m2 for double glazed sliding sash windows


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