Energy Efficiency Towards an optimised performance of buildings

Heat pump heating, wall insulation and thermal glazing are generally known techniques for saving energy. But energy performance is a real catalyst for innovation and the possibilities for optimising energy sources are more diverse. We inform you about the energy performance certificate (CPE) and the 'Klimabank an nohaltegt Wunnen' package, and present the 'Mamerhaff', an outstanding example in the field of energy renovation!

Energy renovation: the "Mamerhaff" is a remarkable and awarded example

The 'Mamerhaff', a family project, is about the transformation of the grandparents' farm into two dwellings and a centre for alternative medicine and family meetings. The architectural reinterpretation of the building goes hand in hand with its functional and energy optimisation. It was awarded the special prize "Exemplary Energy Renovation" in the Bauhärepräis of the Order of Architects and Consulting Engineers (OAI) 2020.

Arnaud De Meyer and Christian Liewer, associate architect and 'project manager' architect at the STEINMETZDEMEYER studio, were in charge of the renovation of the 'Mamerhaff'. The characteristics of their projects are always site-specific and specific to the physical and cultural environment of the place. From the very beginning of the planning process, sustainable development (energy, health, building quality, material savings and environmental preservation) is paramount.

The former dwelling has been restored and transformed into a 21st century home, while respecting the original structure and preserving the testimony of the building. The old barn with its stone arch is now the main entrance to the medical offices. The second habitation is on the other side of the old shed.

The challenge was to preserve the character of the architecture of one of the last well-preserved farmhouses in the centre of the village, while integrating its new functions. In addition, the layout of the existing building on the site no longer corresponded to the new regulations of the municipality. But this landmark in the village, full of emotional memories, has been preserved, including the surrounding trees, which are also part of its heritage. This sustainable approach was supported by the National Sites and Monuments Service.

The barn and dairy were gutted from behind and the roof structure was deconstructed. New wooden spaces were subsequently built behind the façade while preserving the existing openings. The large roof has been rebuilt with metal louvres, to provide discretion and to act as a sunshade, which prevents overheating and manages energy input. 

"The first characteristic of sustainability is that it lasts! You always have to ponder, do we really have to demolish or can we keep what exists? It is more sustainable to keep what is already there." Arnaud De Meyer

The wooden constructions were built with solid wood panels and wood fibre boards, with cellulose and sheep wool insulation (especially for the roof). Even the lift shaft, which connects the three floors of the common area, is made of wood! Wood, a recyclable and renewable material, has a low "grey energy", as it consumes little energy during its production and it allows to store CO2. 

There are many exposed construction elements in the building, implying a saving on finishes from a financial point of view, but also considering ecology and sustainability. Only the necessary materials were consumed. 

The shed at the back of the house has been replaced by a new building. A garage, a a multi-purpose space and the entire technical centre (pellet heating, hot water production, ventilation system, electrical panels, etc.) are located here. Due to the regulations to be complied with in such a mixed unit, the wooden construction is supplemented by solid structures for safety reasons (firebreaks etc.).

Insulation of the former main building was done from the inside with sand-lime blocks to preserve the appearance and nature of the building. The original limestones easily absorb moisture and are very sensitive to frost, and therefore a quality and quantity analysis of the insulation material was necessary. This calculation was performed by a construction physicist.

"Sustainability is not only about the old walls, but also about all the small details that contain a lot of emotion. Old tiles or an old door, things that can be recycled in the house." Christian Liewer

Solar thermal and photovoltaic panels are installed on the roof of the hangar. The flat roofs of the new buildings are green roofs with local honey plants. These roofs not only support biodiversity, but also create a phase shift of rainwater and thus avoid saturation of the wastewater network.

Throughout the house, underfloor heating has been installed to work with low temperature water and low consumption heating.

"From a distance you think, the farm hasn't changed too much. But from close up you can see that it's something new, something today. We are proud to have built something sustainable that allows the contemporary and the historic to live together." Arnaud De Meyer

A quality label 

The energy performance certificate (CPE) defines the energy performance of a residential building. The classification into the different energy performance categories from A (the best class) to I (the worst class) is based on the index of primary energy requirement, heating heat requirement and CO2 emissions.

The energy passport is compulsory. It is drawn up by architects or consulting engineers who are members of the Order of Architects and Consulting Engineers (OAI) and experts approved by the Minister of Energy and Land Management. It is valid for 10 years.

Different grants and subsidies are available for the renovation of a building involving special energy efficiency efforts. Passive house, low-energy or positive-energy house, since 1 January 2017, every new construction of a house in Luxembourg must correspond to a building with almost zero energy consumption. 

"The building of tomorrow"

In 2016, the Luxembourg government presented the package 'Klimabank an nohaltegt Wunnen' (Climate Bank and Sustainable Housing). This project promotes a sustainable construction, sustainable energy refurbishment of residential buildings and renewable energy development in housing.

Thanks to this programme, you can take advantage of the KlimaPrêt to finance the energy and sustainable renovation of your home: The package also includes the sustainability certification system for new housing (LENOZ- Lëtzebuerger Nohaltegkeets-Zertifikat fir Wunngebaier). This attestation is a comprehensive sustainability assessment approach It is optional, but linked to financial support.

A one-stop shop has been created for all housing-related assistance. The website contains all useful information on the subject. 

The Integrated National Energy and Climate Plan (PNEC) forms the basis of Luxembourg's climate and energy policy. It describes the measures taken to achieve national targets for greenhouse gas emissions reductions, renewable energy and energy efficiency up to 2030. As improving the energy performance of buildings is beneficial for the climate, the plan foresees new provisions for functional buildings too.