Minimize, Maximize or Balance: Designing for Net Zero on an Urban Site (WED, 6/14)
January 11, 2023

Quality Control for Highly Energy-Efficient Refurbishments

Quality Control for Highly Energy-Efficient Refurbishments

Darmstadt, Germany. January 10, 2023. The EU project outPHit has now made three concepts for quality assurance in renovations available. The aim is for retrofits to reliably achieve a high level of energy efficiency. The three concepts cover the entire refurbishment process, from planning through preparation for execution to verification of actual energy consumption upon completion. The concepts will be presented in a webinar on January 19, 2023.

The energy efficiency of refurbishment projects is typically only independently certified upon completion. Yet the success of such projects can only be assured with quality checks that already begin in the design and planning phases. The European Union funded outPHit project has thus published three concepts that ensure the quality of the deep energy retrofits throughout the entire construction process.

"Especially in streamlined renovation processes, for example with prefabricated elements, quality checks are of the essence. We want to ensure that the refurbished buildings really do meet the high energy targets set once completed and offer their occupants the corresponding level of comfort. The three newly established concepts are a groundbreaking basis for this," explains outPHit project coordinator Jan Steiger of the Passive House Institute. Renovation projects within the framework of outPHit target the highly energy-efficient EnerPHit standard as developed by the Passive House Institute.


Top and above: Refurbishment of a residential complex in Rotterdam, the Netherlands. Images courtesy of Villanova Architects.

Concept 1: Design Stage Approval

The first of the three new concepts comes into play during the planning phase of the retrofit project. It establishes a preliminary and independent approval of energy efficiency relevant planning before construction begins. This Design Stage Approval procedure offers all parties involved – from the occupants to the architects to the funding bodies – the certainty that the targeted efficiency can actually be achieved. The Design Stage Approval concept for efficiency planning is already being used on a trial basis in the scope of outPHit’s pilot projects.

Concept 2: Renovation System Certification

The actual energy consumption of a refurbished building is also influenced by the quality of the components used. High levels of energy efficiency are best reached when all building elements used work well together. Prefabricated building modules, as used in outPHit projects, make renovation faster, but cannot be reworked on site. outPHit’s second quality assurance concept thus establishes a certification for renovation systems. The whole house renovation system certification concept for entire buildings facilitates compliance with the EnerPHit standard.

Concept 3: Verified Building Performance

The third quality check developed in outPHit is executed after a project has been commissioned. Architects, engineers and other construction stakeholders typically do not receive systematic feedback on the success of a retrofit. This is changed by the certification scheme on "verified building performance”. By verifying the energy efficiency of the building post construction, actual energy consumption in an occupied state can be certified and adjustments to building services settings can be made as needed.

"Lack of feedback on energy consumption in refurbishment projects is a missed opportunity to learn and optimise the construction industry. Verifying building performance will change that. Together, all three newly established concepts are a crucial step in ensuring the quality of deep renovations,” explains outPHit project manager Jan Steiger.


Prefabricated facades being used in a retrofit in Hameln, Germany. Image courtesy of Ecoworks.


The Passive House Institute will present the three new outPHit concepts for quality assurance in a webinar on Thursday, 19 January 2023. "Quality assurance concepts for fast deep retrofit approaches" is an accredited continuing education course. All information can be found on


·         Design stage approval

·         Whole house renovation system certification

·         Verified building performance

·         Webinar January 19, 2023

·         outPHit case studies

·         The EnerPHit standard

Passive House Institute

Passive House Institute

Independent research institute founded 1996 by Dr Wolfgang Feist with a continuously growing interdisciplinary team of employee

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