How well does masonry blocks used in European home construction insulate compared to a well insulated American (wood) wall?

Question

Are there any equivalents to the Building Science insulation reports done for the US/Canada done in Europe?

I spent the last few weeks going over some properties that I will be rehabbing in France and was wondering if there was every any substantial reports done on masonry bricks.

One of the reasons that I ask is that a couple of the properties we were thinking of using more American techniques to add on square meterage but even though I have a good relationship with the inspectors they said they would want to see some substantial support that the methods I use exceed the "normal" methods.

Answer 1

Insulation value of masonry walls vs wood-frame walls

You should be able to find guidance. For example Scottish Guidance, UK Guidance

In the UK, I believe regulations specify maximum U-values

U-values are measured in watts per square metre per degree Kelvin (W/m²K). So for example, if we consider a double glazed window with a U-value of 2.8, for every degree difference in temperature between the inside and outside of the window, 2.8 watts will be transmitted every square meter.

A range of possible U-values are indicated below for the purposes of comparison:

Solid brick wall                2.0 
Cavity wall with no insulation  1.5 
Insulated wall                  0.3 
Insulated roof                  0.2 
Single glazing                  4.8 
Double glazing                  2.8 
Low e double glazing            2 
Triple glazing                  1.5 
Floor                           0.2

Part L of the Building Regulations (Conservation of fuel and power) now prevents certain forms of construction by setting limiting standards (ie maximum U-values) for building elements.

More detailed advice on construction suggests various combinations of materials to meet U-value regulations.

So, if regulations in France were comparable to those in the UK you might need evidence that your constructed wall will have a U-value less than 0.28 W/m²K and that the overall building's U-values still meet regulations.

In France, I imagine your best bet is to find similar French specifications or EU specifications.

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Some notes about U-values, R-Values etc

I have a small "Architects Pocket Book" ISBN 978-0-7506-8617-4 which contains all sorts of strange and wonderful information, including the following:

Thermal Conductivity (K Value)
The heat (W) transmitted through unit area (m²) of a material of unit thickness (m) for unit temperature difference (K) between inside and outside environments, expressed as W/mK

Thermal resistivity (R-value) The reciprocal of thermal conductivity. i.e. mK/W. It measures how well a material resists the flow of heat by conduction.

Thermal resistance (R-value) This measures how well a particular thickness of material resists the passage of heat by conduction, calculated from the R-value in units of m²K/W

Thermal transmittance (U-value)
The reciprocal of thermal resistance. i.e. W/m²K. This measures the amount of heat transmitted per unit area of a particular thickness per unit temperature difference between inside and outside environments.

U = 1 / (Rsi + Rso +Ra + R1 + R2 + R3 ... )

Where

• Rsi = thermal resistance of internal surface.
• Rso = thermal resistance of external surface.
• Ra = thermal resistance of air spaces within construction.
• R1 = thermal resistance of successive components.

Note that for wood frame construction I understand you have to average the U-values for the parts whose cross-section is all wood (where the wooden structural members are) and parts which contain voids or insulation-filled spaces. I assume this has to be an appropriately weighted average (by area of each type of cross-section).

Answer 2

Although I don't have any research numbers to compare for you, I have discussed the building differences from Europe compared to the USA with others more experienced. Generally speaking, in northern climates, you would see more wood framed buildings vs more masonry in southern climates. Masonry walls without cavities have a lower R rating as compared to wood frame of the same thickness with insulation. With that said, however, masonry walls are cooler in summer, so are more popular in the much warmer south. The difference can vary a lot depending on what type of masonry materials used. Besides the climate differences, a major factor in buildings in Europe is the availability and cost of materials. Lumber is not as plentiful. Keeping in mind that people have been living and building and rebuilding in most of Europe for over 1000 years. Masonry products are more durable and available. Forests are limited, many protected and strictly regulated, thus many wood products are imported.

I would be very interested in hearing about your rehab adventure as it progresses. Hope you can post pics and progress reports in the chat section as you go forward. good Luck.