How to design Paris Proof

The ‘Paris Proof’ requirement is increasingly used in requirements programs, both for renovation and new construction. But how do you meet this? For many developers, architects and consultants, there may still be ambiguity around the approach. In this article, we explain what requirements existing buildings and new buildings must meet to become ‘Paris Proof’. You will also find out how you can determine if your building (design) meets the requirements.

A ‘Paris Proof’ built environment may not use more energy than we generate sustainably in the Netherlands. By 2050, we in the Netherlands will only be able to generate 1/3 of buildings’ ‘current’ energy consumption (with 2013 as the reference year), according to research from Royal Haskoning. Our built environment currently uses 3 times more energy than we will have available in 2050. The ‘current’ energy consumption in the existing buildings must therefore be reduced by 2/3 to stay within this energy budget. A new maximum energy consumption per hectare was then defined. square meters per. years for each building type.

An existing ‘Paris Proof’ office building must not exceed 70 kWh per m. From 20402 usable area per year. The crossbeam is set higher for a newly built office: The basic principle is that the current new building will be WENG (Really Energy-neutral Building). A WENG uses 0 kWh / m on the meter on an annual basis2† DGBC states that if the current new construction is not implemented as ‘WENG’, the requirements for existing buildings will in future have to be tightened up in order to achieve the ‘Paris Proof’ objective. This may mean that a new building still needs to be adapted in 2050 to meet the requirements. Or that the requirements for existing buildings are further tightened.

Determination method existing building

The standardized determination method for ‘Paris Proof’ is WEii (True Energy Intensity Indicator), launched in March 2021. The WEii score is determined from the actual, measured energy consumption that can be read on the (main) meters and is related to the building’s usable surface. The unit for WEii score is kWh per. years per. m².

A number of things do not have to be included in the WEii assessment:

  • A charging station for electric transport;
  • An industrial function (other than industrial halls), a workshop, a studio;
  • A cross-building data center;
  • Parking facilities (indoor or outdoor).

The above systems must be measured separately so that they (and the associated user interfaces) can be disregarded when the energy consumption is read. The current WEii tool is designed to assess existing buildings. After all, it is only possible in these buildings to read the actual energy consumption of the meters.

Determination method new construction

There is not yet an unambiguous calculation method for assessing new construction. Currently, two methods are used in the market to map the expected energy consumption of new construction:

  1. An NZEB calculation† A building’s standardized primary fossil energy consumption (NZEB 2 score) is assessed. This assessment method has been developed as an instrument for comparing buildings under standardized conditions. It is therefore less suitable for predicting future energy consumption.

  2. A dynamic energy simulation† A more detailed and reliable method where it is possible to reconcile more with the expected future use of a building than with an NZEB calculation. The disadvantage of this method is that they are much more labor intensive than doing an NZEB calculation.

Design based on BENG2 score

An important difference between the use of the actual energy consumption (on the meter) and the NZEB is that the NZEB method does not determine the actual energy consumption:

  1. The NZEB method is based on standard conditions. The effect of specific user behavior on a building’s energy consumption (climate, usage times, heat production, temperature setpoints, heat demand for domestic hot water, etc.) cannot be mapped.
  2. The NZEB method determines building-related energy consumption for heating, domestic hot water, cooling, fans and lighting. Energy consumption of eg office equipment, server rooms, elevators and escalators is not included. These items are included by WEii.
  3. The NZEB method does not take into account external shadows and obstacles outside the building site. This can have a significant effect on the results, especially when determining the energy yield of solar panels: the energy actually generated can be significantly lower than calculated.
  4. It is also practical that the NZEB2 score is expressed in kWh / m2 primary energy: the energy needed at the source to cover the final energy consumption. The required energy is multiplied by a factor that corrects energy loss during production and transport. In theory, for an ‘all-electric’ office with a BENG2 score of 40 kWh / m², the electrical energy consumption ‘according to the meter’ is 27.6 kWh / m² (PREF = 1.45). To avoid comparing apples to oranges, the BENG2 score must first be converted to non-primary energy.

Design based on a dynamic building simulation

While the NZEB method has been developed as a test instrument, dynamic building simulation software, such as TAS, TRNSYS, IES VE and Energy +, have been developed with the aim of predicting future energy consumption. Even with the use of building simulation software, it is not possible to accurately predict the actual energy consumption, but the results are more reliable than the NZEB method. Compared to the NZEB method, a dynamic simulation can take into account user behavior, user-related energy consumption, and shadows and obstacles outside the plot (points 1 to 3 above).


The ‘Paris Proof’ objective sets stricter requirements for new buildings than for existing buildings. Where, depending on the function of the building, there are approx. 1/3 of the current energy budget available for existing buildings by 2040, all new buildings must be immediately implemented as ‘WENG’: Real Energy Neutral Building.

To check whether an existing building meets the ‘Paris Proof’ requirements, the energy consumption can be read on the building’s meter and entered in the WEii tool. Tools are not yet available to test new construction. Be careful when using the NZEB method when it comes to predicting energy consumption: NZEB is a testing instrument for building regulations, not a design tool. In practice, the actual energy consumption of the meter will always be higher than the calculated BENG2 score, making it uncertain whether your building is ‘Paris Proof’. A dynamic building simulation is intended as a design tool. The building-related energy consumption can be included in a more tailored way and an estimate of the user energy is also included in the calculation. This provides a more reliable estimate of the actual energy consumption of a building.

In a subsequent article, we will discuss the determination of energy consumption for new buildings using dynamic building simulations with examples from practice. And on the feasibility of the premise that all current new construction must be implemented as ‘WENG’.

Text: Hans Tuinenga, Jesse Plas and Merlin Huijbers.

Since the climate agreement in Paris, we have reduced our CO2emissions are high on the agenda. By 2020, it has been determined that we will still have a greenhouse gas emission budget of 400 Gigatons worldwide if we want to limit global warming to 1.5 to 2 degrees Celsius. This is also an important task for the built environment. It has been agreed in the climate agreement that the built environment in 2050 will emit CO2must be neutral. To achieve this goal, DGBC has prepared ‘Deltaplan Sustainable Renovation’ together with more than 60 major market participants. Their ambition is to make the built environment ‘Paris Proof’ by 2040. A large group of builders, developers and consultants signed the DGBC Paris Proof Commitment.

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