Flatmettoekomst - Utrecht (net zero-energy 'flat for the future')

  • by Sandra Winkel
  • /
  • 2019-06-11 13:38:14
  • /
  • International
  • /
  • 3704 / EN
  • Building Type : Collective housing < 50m
  • Construction Year : 2016
  • Delivery year : 2016
  • Address 1 - street : Camera Obscuradreef 48 3561XL UTRECHT, Netherlands
  • Climate zone : [Cfc] Marine Cool Winter & summer- Mild with no dry season.

  • Net Floor Area : 4 000 m2
  • Construction/refurbishment cost : 4 300 000 €
  • Cost/m2 : 1075 €/m2

Proposed by :

  • Primary energy need :
    1 kWhpe/m2.year
    (Calculation method : Other )
Energy consumption
Economical buildingBuilding
< 50A
51 à 90B
91 à 150C
151 à 230D
231 à 330E
331 à 450F
> 450G
Energy-intensive building

Flatmettoekomst won the Sustainable Renovation Grand Prize of the 2019 Green Solutions Awards et the Netherlands level + a mention for the international Sustainable Renovation Grand Prize.

Flatmettoekomst is a net zero energy retrofit of apartment buildings dated from the early sixties of last century. The project consist of 48 apartments. Currently an additional 80 apartments are retrofitted with the same concept.
This renovation is a complete refurbishment of the apartments. Main goal was to deliver a nett zero energy building, but als the renewal of kitchen, bathroom and toilets, upgrade of the communal area's in the building were part of the project. 
Another unique point of the project is bringing it back to the original architectural design.

See more details about this project


Data reliability


Photo credit

ONB architecten, fotograaf: Kim van Zwieten



    Job van Buchem

Construction Manager

    Nieuw Utrechts Peil

    Sandra Winkel



    Vios Bouw

    Sandra Winkel



    Lars Zwart

    Thermal consultancy agency

    Nieman Raadgevende Ingenieurs

    John Bouwman

Contracting method

Other methods

Owner approach of sustainability

The approach of the sustainability from the owner Mitros can be described as following:

To renovate if possible (and not demolish and build new), to save material and environment.

To create at lowest possible costs a zero energy building with reliable techniques, easy to use and maintain.

Architectural description

The socialhousing project which we renovated with the name "flatmettoekomst"(socialhousingwithfuture) consists of a typical industrial building product that was developed after world war II for housing the post war generation.

Some 14.000more or less identical houses of this type were build, 8.000 in Utrecht. They were called INTERVAM flats, by of the name of the factory where they were made: INTERVAM.

Now after60 years of intensive use the question was: can anyone design a renovation model to step into the future with these building blocks? A future were one does not demolish unless unavoidable, a future without fossil fuels, a futurewith affordable houses for many? And last but not least a future with respectfor the industrial architecture of sixties.

After along period of study and experiment our concept was chosen among many alternatives, because: It's energy concept was in a way simple and was functioning well, the design was respectful to the original, the houses are easy to understand and use (our moto is: keep it simple!) and it turned out tobe a realistic business case!

We realized something which we before couldn’t think of. It was completely new but in a way familiar and comprehensive. After the first 8 houses which we build as prototypes we now have renovated about 200 INTERVAM houses in 4 buildings.

One of our secrets is that we isolated cleverly, that is to say: after a deep investigation how the building was constructed we isolated only where needed.Not everywhere to the max. This saves costs and it keeps the architecturealive! But it is not easy. It asks for a close working together with the advisor of building physics and the contractor.

Apart from the energetic and architectural renovation we also attributed to the quality of the social environment. Most of the housing of the sixties have garages and storages placed on ground level. This causes unsafe and unattractive surroundings. In three blocks we succeeded to create extra houses with frontdoors on the street on the ground floor. The next step is the renovation of the gardens, pavements etc. Together with the municipality we strive to remake this area as an example for a social and sustainable future.

Other elements of architectural description :

We chose to be respectful to the original architectural design, as we described above. This was a wish/demand from the municipality of Utrecht. In a way this made zero energy renovation more difficult because of the large windows.

We chose for wooden frames with triple glass resembling the originals. It turned out that this was the most cost effective and air tight.

It was a great challenge to place enough solar panels on the roof in an elegant way. On the roof of the first building we realized  the solar panels are quiet visible. We now have a solution which is nearly out of sight This is being realized now.

All the technical machines are places behind the façade on the back side of the building. Originally there was a balcony on this place. The (second) balcony ofthe same house on the street side was preserved. We succeeded to integrate visibleparts of the machines in the architecture (air in/air out).

If you had to do it again?

What would I do different the next time? Because we worked on this project for several years, step by step we had the opportunity to make it better step by step. These were relative small changes, I described the placing in an more invisible way of the solar panels above.
A question that I asked before we were obliged by the municipality to stick to the original architecture was: can we be more free in the renovation of the façade? We have so many the same buildings of this type in Holland. Can we allow ourselves a renovation with a totally new façade? Hopefully we will get the change someday.
Ir. Lars Zwart, ONB architecten, Utrecht

Building users opinion

During the first year of occupation, an independent party followed the residents and measured their satisfaction with their new home. Satisfaction with the climate system was also examined. The residents give an overall rating of 8 out of 10.

Energy consumption

  • 1,00 kWhpe/m2.year
  • 150,00 kWhpe/m2.year
  • Other

  • 50,00 kWhfe/m2.year
  • heating: 10,9 kWh/m2
    hot water: 14,2
    cooling: 0
    ventilation: included with heating
    household: 24,8 kWh/m2

    Total energy demand is generated by solar pv-panels; total energy consumption equals the total energy output of the panels

  • 225,00 kWhpe/m2.year


    • Heat pump
    • Water radiator
    • Heat pump
    • No cooling system
    • Double flow heat exchanger
    • Solar photovoltaic
    • Heat pump
  • 100,00 %

Smart Building

    Tennants were not directly involved in the design phase. A representation of tennants was participating in the clients team and advised the client during the selection and clarifaction of the design.
    Tennants review their apartments with an 8 out of 10.

Indoor Air quality

    A double flow ventilation system with heat recovery is part of the nett zero energy concept. The ventilationsystem is controled through CO2 sensoring. The installation increases and decreases ventilation flows as a respond to the CO2 concetration. This gives a guarantee on good indoor air quality as well on reducing energy consumption by ventilation as much as possible.


    Energy Module Factory Zero


    S. Klein Velderman

    Génie climatique, électricité / Chauffage, eau chaude

    Factory Zero delivers a completely integrated system for heating, domestic hot water supply, double flow ventilation and monitoring.

    Factory zero delivered a total concept and had experience in other zero energy projects. They were able to make a tailor made solution that fitted exactly on the (former) balcony.

Construction and exploitation costs

  • 4 300 000

Urban environment

The project is a retrofit of existing apartmentbuildings to nett zero energy apartments. The building is located in Overvecht in Utrecht. Next to the 48 apartments we describe in this contest, another 80 apartments adjacent to this building have been refurbished with the same nett zero energy concept. 

At the same plot we have also renovated 120 apartments to energylabel A++ using the same principles of the concept, but with a lower energy performance. These apartments are heated by natural gas boilers. In the future these boilers can be exchanged by heatpumps.
Apart from the energetic and architectural renovation we also attributed to the quality of the social environment. Most of the housing of the sixties have garages and storages placed on ground level. This causes unsafe and unattractive surroundings. In three blocks we succeeded to create extra houses with frontdoors on the street on the ground floor. The next step is the renovation of the gardens, pavements etc.

Together with the municipality we strive to remake this neighbourhood as an example for a social and sustainable future.

Building Environmental Quality

  • indoor air quality and health
  • energy efficiency
  • renewable energies
  • maintenance
  • building process
  • zero energy retrofit of 5-storey apartment building
  • with respect for the original architectural design (the original design is brought back)
  • use of an integrated energy module for heating, hot water, ventilation and energy monitoring
  • much attention for tennants comfort and health
  • user-friendly installation
  • creating energy effiecient and healthy homes by using CO2-monitored ventilation
  • very satisfied tennants (review 8/10)
  • total energy demand is produced by PV solarpanels.

Contest categories

Energy & Temperate Climates

Energy & Temperate Climates

Low Carbon

Low Carbon

Health & Comfort

Health & Comfort

Users' Choice

Users' Choice

Green Solutions Awards 2019 - Buildings

 Green Solutions Awards Winner
 Sustainable Renovation Grand Prize

Author of the page

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    Green Solutions Awards 2019 - Buildings