BIM is an acronym describing digital design, construction and facilities management in the construction industry. "B" stands for building of course, "I" for information and "M" is not clear yet but it may be interpreted as Modelling or Management depending if you are designing or managing the project.

However the National Institute of Building Sciences in the United States put some light on this subject stating that BIM is:

“A digital representation of physical and functional characteristics of a facility… and a shared knowledge resource for information about a facility forming a reliable basis for decisions during its life-cycle; defined as existing from earliest conception to demolition.”

As the above definition didn't help us at all, we decided to look through some RIBA publications. That was even more confusioning, we found out that anybody can say what they want about BIM.

On our side we put a lot of effort in pursuing the perfect BIM definition and now we are pretty confident in saying that BIM is a multidisciplinary approach to the design, construction e management of a building (or infrastructure). Various disciplines are involved in the design of a building, such as architects, structural engineers, mechanical and electrical engineers. All of them are working on the same digital model. In this way everyone involved must work and collaborate together with the same standards. If one discipline fail to deliver his package the team fail in delivering the project to the client.

All seem pretty amazing but, as Mr D. Tail is trying to explain us, the theory may be different from the practice. 

#032 - U-VALUE

The U-value is a measure of heat loss in a building element such as a wall, floor or roof. The higher the U-value the worse the thermal performance of the building envelope is. According to Passive House Design standards all elements of the external envelope of the building should combine to provide a U-value of not more than 0.15 W/(m2K).

In order to calculate the U-value we should know the build-up materials of the building element, their conductivity properties and thickness.

For instance, a 200mm brick wall have high conductivity and facilitate the passage of heat/cold, on the contrary a 100mm insulation panel, usually installed within the cavity of the external walls, has low conductivity and slowly release the heat/cold .

This is why a contemporary insulated house is more energy efficient of a Victorian house. Mr D. Tail is definitely feeling more comfortable in a well-insulated house with a low U-value building envelop.


According to a recent survey*, nearly 95% of architects think that working on aluminium window details is the most boring experience ever faced in their profession.

Having taken seriously this upsetting revelation, we asked Mr. D Tail what he thinks about it. What is surprising is that, on the contrary, he found the subject pleasantly puzzling and challenging.

Have your say.

*the survey was never undertaken


Probably here we need some explanation to all of those are not familiar with the science of construction.

The second graphic is called “free body diagram”. It represents a cantilever beam with fixed support like the one where Mr D. Tail is standing on enjoying the sunset but strip out from all insignificant and irrelevant detail (insignificant for an engineer).

Any geometric structure is effected by loads, in our case by Mr D. Tail. These loads are manifested as external forces and represented to the free body diagram with arrows (F).

This simple diagram is used by the structural engineers as method of calculation to analyse how a force effecting the structure in order to dimension each element.

More info on Wiki: