Wall of the Future: A Historical Perspective of the Building Envelope;

Part 1

Building Science Forum 

By Petr Vegh, Ph.D., P.Eng. Greg Hildebrand, M.Sc. (Eng.), C.E.T. and Brian Burton

(This is the first of a two-part exclusive for the Monster Commercial Website.)

In today’s world we accept that the performance of the components which comprise the building envelope*, a term that describes the perimeter walls and roofing systems that separate the indoor and outdoor environments, is a very complex topic from a scientific, psychological and cultural perspective. (*The term “envelope” has become common in describing enclosure systems because over the past 4 decades the components have tended to become lighter and lighter and also much thinner – hence the word envelope.)

Of course it is generally acknowledged that the elements contained in the building envelope systems tremendously important and vital components of these modern building systems.

We also recognize that, in addition to becoming more and more intricate, buildings are also tremendously important to humans – they always have been and always will be.

The study of the building envelope has been primarily focused on the performance characteristics relating to the 7 key functions as follows:

• Ensure the health, safety and comfort of the occupant
• Control the flow or movement of air, heat, and water vapour 
• Control rain penetration, light, solar and other radiation
• Control noise and fire
• Provide strength, security, rigidity and durability
• Provide access and egress
• Be aesthetically pleasing and economical

For this particular article we researched a number of sources relating to historical information about the functions of the building envelope and will present key issues in general order of importance.

Unending Search for Better Security: Putting aside for the moment the fact that we are always attempting to build bigger and taller buildings – based on the historical documentation it’s clear that the physical protection of the occupants and their personal property undoubtedly rates as the number one factor in overall importance. 

(The importance of security can be seen in the huge investment of resources in buildings that were designed primarily to provide protection of the occupants and, at the same time, protection of valuable materials.)

In the past these essential assets include a long list of items ranging from food stock, water, weapons, materials for fabricating weapons, materials required for hunting and gathering),religious artifacts and materials that might be classified generically as “trading tools”.

These items could also include virtually any material relating survival and the acquisition of worldly goods and wealth — surprisingly even the health, safety and comfort of the occupants, in relative terms, appears to have been viewed as a secondary consideration.

Mobility: From a historical point of view the ease of construction and “mobility” of buildings were also considered very important factors – a consideration we rarely take into account in today’s world. This is partly because when humans survived as hunters and gatherers they were, and in some cases still are, constantly on the move.

We were somewhat surprised that the efficient use of existing resources did not appear to be an important consideration in many civilizations and if we correct buildings were not typically viewed as an “investment” as we treat them today until sometime in the 1920’s or 30’s.

Rather than comfort, the buildings were designed to provide “environmental separation” and protection from inclement weather of all sorts, precipitation in all its forms, temperature variations, wind, particulate matter, unwanted solar radiation, and intrusion.

We have also gradually come to expect of course, that enclosure systems will provide natural ventilation, daylighting, access and/or egress and a “view” of the outside environment – but this expectation hasn’t always been the case.

Although it is often overlooked the building envelope or enclosure actually provided a sense of “dimension”. Building were also suited for decoration and ornamentation and in some very early historical examples the buildings, rather than providing security and/or comfort, were more likely a symbol of personal, governmental and/or political power.

In other words, buildings served as a symbolic representation that demonstrated the relationship between the King/priest and the citizens. (Early examples would be that Palace at Knossos (Crete 1700 BC) Pyramids of Egypt (2400 BC)

Putting aside for the moment the fact that we are always attempting to build bigger and taller buildings - based on the historical documentation it's clear that the physical protection of the occupants and their personal property undoubtedly rates as the number one factor in overall importance.

In effect, these spatial enclosures served to protect and celebrate the power of the community, the state, the powers that be, or in some cases individuals. This can be seen quite clearly in monolithic structures, not all of which were buildings, such as the Great Wall of China* the Pyramids, and later the construction of temples, cathedrals and castles.

(*The Great Wall of China is a good example of the links that humans will go to ensure security. Most scholars believe more than 1 million Chinese died in its construction, most of whom are buried beneath the wall.)

Obviously there are many other factors involved here in addition to protection from the elements.

For example we noticed that there were many examples where buildings were actually works of art – rather than structures designed for human occupancy. In fact one famous architect stated that houses were in reality “machines for living in”.

About the Authors

Petr Vegh, Ph.D., P.Eng. the Head: Structural Group of exp. Petr is also is a Member of the Executive Council International Association for Shell Structures (IASS) Association and a Reviewer of the International Journal of the IASS. Petr can be reached at mailto:Petr.Vegh@exp.com                            

Greg Hildebrand, C.E.T., M.Sc. (Eng) is the Head, Façade Engineering Group, Building Engineering Team and is Chair of the CAN/CSA A440 task group. Greg can be reached at greg.hildebrand@exp.com 

Brian Burton is an R& D specialist for exp as is a certified CGSB/ICPI Construction Inspector. brian.burton@exp.com Or visit www.exp.com 

The next issue will focus on classification of building enclosures and materials employed around the world

Tags: Building Envelope

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