Benefits versus price – from the point of views of the contractor and the investor/operator
What is the difference between the mindsets of engineers and business professionals? Engineers are aware that “things that may break down will break down”, therefore they aim at proper safety. Business professionals believe that the things that may break down will either break down or not – in other words they take risks.
Contractors rather seem to be driven by a business attitude (small investment – big profit), while Investors/Operators tend to have the approach of engineers (reasonable investment – reliability). Of course this is a simplification of the vested interests of the stakeholders, but we should not forget that there are a lot of actors involved in construction activity, who sometimes seem to have opposing interest. If, however, all the building components and elements are constructed with a complex approach and on a scientific basis, then the results will be beneficial for everybody:
- Developers/Investorswill get the quality they need,
- Operators will be able to ensure the operation of the building as expected, in the pre-planned manner and with the pre-planned amounts of investment,
- Contractors may confidently face up to the challenges concerning their works, which, if successfully implemented, will increase their professional reputation, self-confidence, their own and their customers’ satisfaction, while their realistic investment will generate realistic profit.
It is an open secret that in most areas of the market, manufacturing that follows and orientates consumers’ demands works with pre-planned lifespans (i.e. relatively fast obsolescence/wear and tear). However, in construction, especially in the case of materials that are covered, we cannot afford using structures with a significantly lower lifespan than that of the building. This situation may be acceptable where the structures can be “replaced” in the framework of planned reconstruction. However, in places where this is not possible (e.g. under the buildings, inside wall structures, in the case of superstructures whose weight is borne by thermal insulation, such as the roof structure of roof slabs etc.) the expectation of reliability for several decades is not unrealistic. The solution, however is not cheap, easy or simple.
It is a well-known fact that the thermal insulation efficiency of heat insulating materials is primarily determined by the dry air (or maybe other gases) with no flow enclosed partially or completely in the different materials and the thickness of the thermal insulation materials. If the air flows, then it will carry the heat, among other things. If the material is moist, then,instead of well insulating air, water, a good heat conductor, will play a more prominent role.If the thermal insulator is pressed or crumbled, then only a fraction of the original thickness will be able to have its effect.
There are only few heat insulating materials that keep their original characteristics even in a moist environment while they are also highly loadable. One of these is the family of RAVATHERM XPS extruded polystyrene foam heat insulating products, which fully comply with the above mentioned demands.
It is a closed-cell product, where the condition of the enclosed air does not change either in its structure or as a result of surface air flow (e.g.in breathable structures). Its water absorption is so small that it is almost negligible.
Its loadability (its compressive strength is 300-700 kPa) allows it to bear the biggest construction loads without any significant deformation. All these and other favourable characteristics make closed-cell polystyrene foams (XPS) belong to the higher performing heat insulating materials of a higher price category.
What is offered to different stakeholders for the higher price?
- To Developers/Investors: permanent safety and reliability,
- toOperators: throughout the product lifespan all the expected technical performance and a lifespan twice or three times as long as in other cases, with lower maintenance costs,
- to Contractors: simple malleability, favourable installability, proper resistance to the extra demands arising during building and the opportunity to provide long-term guarantees.
During the planning must take account of the building must meet the basic requirements of
a) stability and mechanical resistance,
b) fire safety,
c) hygiene, health and environmental protection,
d) safe use and accessibility,
e) protection against noise and vibrations,
f) energy saving and thermal protection,
g) protection of life and assets, and
h) sustainable use of natural resources, as well as the expectations described in detail in the planning programme.”
Although here the group of requirements most closely related to thermal insulation is “only” the sixth in the list, we must not forget that informed structural design together with thermal insulation impacts almost all areas.
Returning to the goal described in the title, it is worth considering the following questions: Where should thermal insulations be placed in our present and future buildings and what stress must they endure while retaining their basic heat insulating capacity for their full lifespan?
Mechanical forces + vapour load
|Place of installing thermal insulation
|Under building||Permanently high compressive load + permanently moist environment|
|At basement level, in contact with soil||Permanently moist environment + earth pressure|
|At terrain level||Frost pressures in a variably moist environment + mechanical forces|
|In slabs and floors||Compressive loads depending on purpose of use + sheer forces|
|Outdoors||Weather pressures + mechanical forces|
|In roofs (under the rafters)||Pressing-bending pressures + thermal effects|
|On roofs||Flat||Compressive loads depending on purpose of use + moist environment + thermal effects|
|High||Variable compressive loads + vapour/moisture|
If we want to fully comply with the provisions prescribed in the above, the materials in each place of use must be resistant to the pressures and loads generated typically at that place.
In most cases, prices cannot be decisive, since if cheap, low performance materials are used, all stakeholders may experience – often unpredictable – damages.The Developer will suffer direct and indirect damages, the Operator will not be able to ensure the expected economical and optimal operation, and the Contractor – beyond the damage to his reputation – as a result of the necessary repair works, will be forced to invest in the facility several times the amount of the “easy” profit originally hoped for.
At a building site where facilities with a longer lifespan are constructed, focussing on reliability and permanent safety may be the right attitude of all those concerned. And here the principle of “less is more” cannot be applied. Instead, the principle to be followed is “the right material to the right place”, without compromises, and the product whose performance is the most perfectly suitable for the given circumstances should be chosen and installed.