The building envelope: concrete perspectives for a global quality approach

Many construction projects show significant lags between expected energy performance and that obtained during the operation phase.

After having pointed out the aspects to be considered and to be deepened concerning the quality of the envelope, the Working Group on the Quality of the Envelope (GTQE) endeavors, in this 3rd component, to propose perspectives to tend towards a high-quality envelope, in particular through the so-called “commissioning” method, the contribution of digital technology and the automation of measurements and checks.

Commissioning, quality monitoring from programming to operation

The commissioning of a building can be understood as a global quality approach which aims to guarantee the conformity of the performance of the building with the contractual documents. It differs from the notion of “commissioning” which consists of a partial mission of assistance and assistance in the commissioning of equipment. The Anglo-Saxon approach defines it moreover as a complete quality management tool, the objective of which is to avoid too great a gap between the objectives set upstream, the resources that can be mobilized and the results obtained. In addition, it is necessary to exceed the single target of an energy consumption figure as a criterion for evaluating performance and managing projects, knowing that comfort and air quality are just as essential. .

The GTQE deplores the obstacles to the development of this method

• The specifications for the operation at the programming stage are generally not very qualitative, without specifying the level of performance expected in operation.
• The quality factor is thus often left aside by the contracting authorities, being satisfied with obligations of means and not of obligation of result.
• Finally, too few technical, methodological and financial resources are available to achieve the ambitious operational objectives due to the lack of analysis of the costs associated with non-quality.

Moreover, if we note that the cost of the complete commissioning of a new building represents approximately between 0,6 and 1% of the total cost of the operation (including the costs of project management, work and construction2), the return on investment is estimated between zero and ten years, depending on the type of gains included (energy consumption alone or all direct and indirect gains). It should also be noted that this data may vary depending on the complexity of the operation and the scope of the commissioning mission. On the other hand, the reduction in non-qualities will de facto imply a significant reduction in internal costs (detection, correction, prevention, etc.) as well as external costs, often borne by the customer (decrease in productivity, use of emergency equipment, additional costs associated with energy consumption, dissatisfaction, loss of reputation, etc.). In this regard, it should be remembered that a study by the Lawrence Berkeley National Laboratory3 estimates that if the gains in energy savings range from 0,21 to 2,05 $ / m², the indirect gains (savings in modifying or curative work, costs maintenance…) can amount to up to $ 74,9 / m²!

“Commissioning is essential as part of the PROJECT's quality approach. The approach represents an upstream investment to prevent downstream non-qualities and to ensure a smooth warranty period as well as a high perceived value of the PROJECT.
Commissioning should be interpreted as the implementation of a total quality management tool, based on integrated validation processes throughout the life cycle of the building, and at least over the entire duration of the PROJECT, since from initial programming to delivery, with optional integration of the operating phase for the first years. Consequently, the expectations of commissioning and the resulting value creation are the issuance of a validation of a building, mainly based on the continuous assessment of the performance and conformity of its envelope and its components. technical equipment. " Edward WOODS, Director of the Technical Pole - Commercial Real Estate at Bouygues Immobilier.

Digital, automation of measurement and verification at the service of quality

For the GTQE, the use of digital technology can have a significant impact on the overall economy of a construction project. Better still, it can genuinely improve lead times, limit or even avoid human errors. Given the importance of technical expertise to ensure the commissioning mission, their generalization poses an issue of economic model.

"It is therefore necessary to imagine the contribution of digital technology to allow the deployment and appropriation of this practice to all projects in the territory with a pooling of knowledge, good reflexes and virtuous practices, in particular concerning quality thermal insulation of the building envelope. It seems legitimate to imagine avenues for using digital technology in order to assist building stakeholders in their efforts to improve the overall quality of operations. A key factor in a context of accelerating BIM dynamics where much remains to be done. "And to conclude:" Digital technology represents a great opportunity to analyze and share experiences, the successes of which will continue to advance the entire sector. " Jean-Luc SADORGE, Managing Director of the Fibers-Energy Cluster

As an example, let us mention that the company CMDL - MANASLU Ing. is developing an innovative automated measurement solution which will make it possible, during the acceptance of buildings, to carry out an exhaustive check of the occupant's comfort conditions necessary for the preliminary acceptance operations, and to measure the performance of artificial lighting, following a network of zones compliant with standard EN 12464.

The GTQE actively campaigns on 4 fundamentals to be respected for a RE2020 guaranteeing the quality of the envelope

RE2020 must be ambitious in order to achieve the objectives of the National Low Carbon Strategy, with a very specific requirement on the Bbio indicator positioned at RT2012-40%. The average level of collective buildings produced between 2012 and 2018 shows a Bbio RT2012-20%, an RE2020 with a requirement of Bbio at RT2012-10% would represent a decrease.

Primary energy consumption (Cep) must be equivalent to: standard RT 2012 - 20%

It is necessary to treat thermal bridges correctly. The aspect must be non-derogatory at the risk that recourse to the derogation becomes systematic. The advantages of thermal bridging treatment are not limited to combating the risk of condensation. They reduce energy consumption, heating costs and GHG emissions, while improving comfort in summer and winter, air quality and, finally, the prevention of sources of structural disorders.

It becomes necessary to update the libraries of regulatory calculation tools. Indeed, the thermal performances having evolved favorably with thermal resistance of the current walls increasing, the influence of thermal bridges becomes predominant.

Members of the Envelope Quality Working Group: Pôle ALEARISQUE, DRABER-NEFF, insurance broker, energy engineering firm MANASLU, company MEDIECO, Groupement du MUR MANTEAU, design office POUGET Consultants, company SCHOCK France, National Union of Insulated Cladding and Cladding (SNBVI), FIBER-ENERGY Pole.