Calculation tools
=================

The Nationale Milieudatabase (NMD), managed by Stichting NMD, was established to enable unambiguous calculation of
`environmental performance of construction works`_ in the Dutch context. The NMD contains validated
:ref:`environmental data` on
:ref:`Construction Products (or processes)<construction-product-or-process>`, formulated in accordance with an :ref:`assessment strategy`.
These environmental data are used in various third-party applications (also referred to as 'calculation tools')
pre-validated by Stichting NMD, to calculate the environmental performance of construction works.
Together with the calculation rules described in
`Environmental Performance Assessment Method for Construction Works <https://milieudatabase.nl/media/filer_public/89/42/8942d5dd-8d37-4867-859a-0bbd6d9fb574/bepalingsmethode_milieuprestatie_bouwwerken_maart_2022_engels.pdf>`_.
this ensures verifiable, reproducible, and unambiguous calculation results. The NMD does not perform any calculations itself.

Entities described in this section are outside the scope of the database. They exist in the calculation tools that use the
data provided by the NMD. However, to understand the complete picture, it is important to define them here.

.. graphviz:: conceptual-model-calculation-tools.dot
    :caption: Schematic overview of conceptual model zoomed at Calculation Tools
    :name: conceptual-model-schematic-calculations-tools

Environmental Performance of Construction Works
###############################################

The environmental performance of construction works is calculated by aggregating the  :ref:`Environmental Data`
of the :ref:`Construction Products (or processes)<construction-product-or-process>` used in the building or structure
and the number of product replacements during the :ref:`Construction Work`'s life.  
This takes into account :ref:`Construction Products (or processes)<construction-product-or-process>` used in the building
or structure and the number of product replacements. The calculation is performed according to the document
`Guide To Environmental Performance Calculations <https://milieudatabase.nl/wp-content/uploads/2020/09/Guide_to_environmental_performance_calculations_July_2020.pdf>`_
, using the `Environmental Declarations <Environmental Declaration>`_ provided by the NMD.

Construction Work
#################

Construction Works are works or structures that are constructed or are a result from construction activities. It can be
described as a set of :ref:`Construction Products (or processes)<construction-product-or-process>` including replacements
during the :ref:`Construction Work`'s life.