September 8, 2023

How much heat is lost through a conservatory roof?

Conservatories are a great way to add extra living space to your home; however, they are notorious for being inefficient when it comes to retaining heat. This is largely due to the amount of heat that can be lost through the roof. Here is an overview of how much heat is typically lost through a conservatory roof and what factors affect it:

How Heat is Lost Heat is lost from a conservatory through the roof in three main ways:

  • Conduction – Heat flows from the warmer air inside the conservatory through the roof materials to the colder outside. This depends on the thermal conductivity of the materials.
  • Convection – Warm air rises and leaks through any gaps, joints or openings in the roof, taking heat with it.
  • Radiation – Heat is radiated outside from the warmed interior roof surfaces towards the colder exterior surfaces and sky.

A conservatory roof can lose heat through all these methods simultaneously, leading to significant heat loss if poorly insulated.

Measuring Heat Loss Heat loss is measured in units called U-values (sometimes known as heat transfer coefficients). The lower the U-value, the better the material is at retaining heat.

The U-value specifically indicates the rate of heat loss in watts per square metre per degree Celsius temperature difference (W/m2C).

Typical U-values for conservatory roof materials are:

  • Glass – 5.8 W/m2C
  • Polycarbonate – 3.0 W/m2C
  • Double glazing – 2.8 W/m2C
  • Insulated glass – 1.4 to 1.2 W/m2C

So for example, a 10m2 conservatory roof made of standard glass would lose around 58W of heat energy for every 1°C temperature difference between inside and outside.

Factors Affecting Heat Loss There are several variables that influence the amount of heat lost through a conservatory roof:

  • Roof material – As shown above, standard glass loses heat the quickest while insulated glass retains it better.
  • Glazing type – Annealed glass loses heat faster than toughened, laminated or double glazed.
  • Number of glazed panels – More panels mean more surface area for heat to escape.
  • Quality of seals/joints – Any leaks or gaps will increase convection heat losses.
  • Roof insulation – Adding insulation above or below glass panels slows conduction losses.
  • Roof pitch – Steeper pitch angles speed up convective loop heat losses.
  • Direction faced – South facing roofs receive more solar gain to offset some heat loss.
  • External shading – Eaves, overhangs or blinds reduce solar gain in summer.
  • Internal blinds – Help reduce radiative and convective heat losses at night.
  • Outside temperature – The colder it is outside, the greater the temperature difference driving heat loss.

Impacts of Heat Loss The main impacts of excessive heat loss through a poorly insulated conservatory roof include:

  • Discomfort – Cold draughts, chilly floors and room surfaces.
  • Higher energy bills – As more heating is constantly required.
  • Condensation – Leading to mould growth on windows and ceilings.
  • Furniture damage – Due to dampness from condensation.
  • Noisy during rain – From amplified sound on glass or polycarbonate panels.

Reducing Heat Loss To minimise heat loss through the roof, it is recommended to:

  • PanelX Conservatory Roof Panels
  • Add thermal insulating blinds
  • Install quality insulated glazing units
  • Seal any leaks or gaps thoroughly
  • Add specially designed conservatory roof insulation
  • Consider replacing entire roof with insulated composite roof panels or conversion to a tiled roof with added insulation.

While complex to calculate exact amounts, it is clear that conservatory roofs can lose substantial heat through various mechanisms. Proper installation of insulated glazing,ventana, and elimination of gaps is key to reducing heating costs and avoiding potential dampness issues. With the right improvements, conservatories can be enjoyed year-round.