The Spanish Technical Building Code is one of the three royal decrees that were approved in Spain as a consequence of the transposition of the European Directive on the energy performance of buildings (2002/91/EU, 2002). One basic document of the Technical Building Code deals with the limitations of building energy demands. Nowadays, due to the recast of the European Directive on the energy performance of buildings (2010/31/EU, 2010), a revision process of the current regulations has begun, starting with the Technical Building Code, with its first revision envisaged for 2012. In this paper we, as collaborators in this updating process, describe and analyse the main changes regarding ventilation and infiltration that the “new” Technical Building Code (TBC) is going to introduce. These main changes cover:
--The calculation methodology;
--The ventilation technologies that can be considered;
--The default values and the data that the user can supply to assess particular cases.
Basically, these changes make it possible to move from a previous regulation that considered:
--One indoor pressure and one outdoor pressure, assuming all the indoor spaces as a single-zone (calculation methodology EN 13465 (2004));
--A constant extraction flow for 24 hours a day, without the possibility of using a control system;
--No possibilities of changing the sizing of vents, default behaviour curve of the vents and air permeability of opaque elements according to EN 13465 (2004).
To a new regulation that considers:
--One indoor pressure and one outdoor pressure (calculation methodology EN 15242 (2007)) but keeping indoor zoning that allows calculating (using mass conservation) the airflow between zones;
--The possibility of using a control system allowing different flows each hour for a demand controlled ventilation scheme and pre-heating of supply air flow;
--The possibility of sizing vents, using self-regulating vents and changing the air permeability of opaque elements, for example if a blower-door test has been carried out.