PR2015

Choosing the right baseline level of ventilation has a big impact in the calculated energy needs of buildings.

The north of the Iberian Peninsula is characterized by a high level of humidity during the summer.

Recently research at the Eduardo Torroja Institute for construction sciences proposes a new wording for the IAQ regulations for dwellings included in the Spanish Building Code.
The main goal of the earlier research was to adapt required ventilation rates to real needs to achieve a reduction of ventilation rates and energy demand with no negative impact on indoor air quality.

The Spanish Building Code (BC) regulates indoor air quality (IAQ) requirements in dwellings by establishing threshold continuous flow rates according to the occupancy, use of the rooms and their usable area. The implementation of this threshold flow allow adequate IAQ.
A revised IAQ requirement have been proposed. These new requirement quantifies the IAQ as a function of CO2 concentration which means an non continuous flow rates ventilation systems will be able to be used.

For zero and low energy buildings, high-energy efficiency ventilation is very often confused with a complex mechanical ventilation system with heat recovery. In school gymnasiums, where large volumes have to be ventilated, and where intermittent occupation is very usual, demand controlled natural ventilation has several advantages, making this technique very attractive. High stack height makes natural ventilation very efficient, limiting the necessary number and dimensions of windows.

Ventilation in low energy refurbished buildings is the cause of a big part of energy losses. In order to reduce this impact, some energy regulations prescribe a solution (such as the Swiss energy Law, prescribing heat recovery) and others prescribe a system global performance (such as the EU delegated regulations No 1254 and 1253 /  2004 determining a global energy performance label of the ventilation system).

In response to the European Energy Performance Buildings Directive 2010/31/EU and the Energy Efficiency Directive 2012/27/EU, buildings have increasingly become more insulated in order to reduce the heating losses to a minimum. However, this could also lead to the problem of indoor high temperatures during warm and transition seasons. Furthermore, the Intergovernmental Panel on Climate Change (IPCC) warns about increases in temperature of more than 4 ºC by the end of the century.

Because of the customer need of best possible comfort condition and satisfaction, shopping centers are conditioned by means of basic HVAC systems, often without considering the potential of natural ventilation to contribute to air change rate, and to reduce the cooling demand. Mechanical ventilation systems are also preferred to natural ventilation because more controllable and reliable since they are not affected by the uncertainty of natural forces.

New buildings have to satisfy ever-tightening standards regarding energy efficiency and consumption. This results in higher insulation levels and lower air leakages that reduce heating demands. However, even at moderate outdoor temperatures these buildings are easily warmed up to such a degree that in order to ensure acceptable indoor environment quality, removal of excess heat becomes unavoidable. Use of electric energy related to mechanical cooling is considered incompatible with achieving zero energy buildings (ZEB).

EU energy policy encourages member states and public authorities to start converting building stock into nearly Zero Energy Buildings (nZEB) and adopting exemplary actions. ZEMedS project focuses on the issues related to the refurbishment of schools to nearly Zero Energy Buildings (nZEB) in France, Greece, Italy and Spain. Presently, there is a gap in national regulation of Mediterranean countries to embody the 2012/27 EED as far as renovation rates of public buildings are concerned.