How does ventilation impact global energy consumption- EN 15241

1. How does ventilation impact global energy consumption- EN 15241 Hicham LAHMIDI CSTB / Francehicham.lahmidi@cstb.fr

2. Outline • The EU CENSE project • Scope of the Standard • Principle of the methods • Energy impact of the ventilation devices

3. The EU CENSE project (Oct. 2007 - March 2010) Aim of the project: To accelerate adoption and improved effectiveness of the EPBD related CEN- standards in the EU Member States These standards were successively published in the years 2007-2008 and are being implemented or planned to be implemented in many EU Member States. However, the full implementation is not a trivial task Main project activities: • To widely communicate role, status and content of these standards; to provide guidance on the implementation • To collect comments and good practice examples from Member States aiming to remove obstacles • To prepare recommendations to CEN for a “second generation” of standards on the integrated energy performance of buildings

4. Brief introduction A brief introduction to the CENSE project and the CEN-EPBD standards is provided in a separate presentation:

5. More information More information and downloads: www.iee-cense.eu Disclaimer: CENSE has received funding from the Community’s Intelligent Energy Europe programme under the contract EIE/07/069/SI2.466698. The content of this presentation reflects the authors view. The author(s) and the European Commission are not liable for any use that may be made of the information contained therein. Moreover, because this is an interim result of the project: any conclusions are only preliminary and may change in the course of the project based on further feedback from the contributors, additional collected information and/or increased insight.

6. Scope of the Standard EN 15241 • This standard aims to calculate : • The air characteristics of the supply air • The power required for air treatment • The air characteristics of the supply air • The air temperature • The air humidity • The air flow

7. Principles of the methods • For each system covered by the standard, the method provides the relation between the air characteristics before and after a component in the system, with or without air treatment and the power required if there is an air treatment. • The components in the systems taken into account are : • Ducts, Fans, Heat exchangers, Mixing boxes, Pre-heating devices, Pre-cooling devices, Humidifiers, Dehumidifiers. • The standard describes three methods : • A hourly method • A monthly method • A statistical method

8. Energy impact of……… • 1- Duct heat losses • The standard takes into account : • The position of the duct (inside or outside the conditioned area) • The flow rates in the duct calculated according to EN 15242: The heat loss from the duct to the surrounding in W/K (conduction losses) • Impact on air characteristics • Description of the calculation of • No variation on the air humidity • No variation on the air flow • Impact on energy consumption • There is no power required

9. 2- Fan • The standard takes into account : • The type of system (VAV, DCV) • The fan power in W • The fan recovered ratio • The air density • The air specific heat • The air flow through the fan • The regulation of the fan. • Impact on air characteristics • Description of the calculation of • No variation in air humidity • The air flow through the fan is given by a design calculation • Impact on energy consumption • The power required depend on the air flow through the fan

10. 3- Heat exchanger • The standard takes into account : • Defrosting issues and its associated heat power • Free-cooling-limitation of supply temperature • Impact on air characteristics • The variation of supply air temperature • There is no modification on air humidity • There is an air flow variation through the heat exchanger • Impact on energy consumption • The power required by defrosting devices

11. 4- Mixing boxes The input data : The ratio of recirculation air in supply air There is no air treatment considered in the mixing boxes

12. 5- Pre-heating • The pre-heating calculation takes into account the set value of the temperature. • Impact on air characteristics • The temperature is fixed to the set value • The air humidity is unchanged • The air flow is unchanged • Impact on energy consumption • The power needed for preheating is directly calculated • 6- Pre-cooling • The input data : The set value of air temperature • Impact on air characteristics • The temperature is set value when the systems is on • The air humidity variation is calculated • The air flow is unchanged • Impact on energy consumption • The formula for the pre-cooling power is similar to the pre-heating, with one exception: it includes also air humidity.

13. 7- Humidifying air in winter The input data : The set value of air humidity Impact on air characteristics The temperature is unchanged by the device The air humidity variation is calculated The air flow is unchanged by this system Impact on energy consumption The air flow rate through the humidifying device The required air humidity. 8- Dehumidification The approach is the same as for the cooling calculation and pre-heating calculation. The standard introduces a bypass factor for the cooling coil.

14. Conclusion This standard provides flexible methods to calculate the power needed for air treatment systems in buildings.

15. More information More information and downloads: www.iee-cense.eu Disclaimer: CENSE has received funding from the Community’s Intelligent Energy Europe programme under the contract EIE/07/069/SI2.466698. The content of this presentation reflects the authors view. The author(s) and the European Commission are not liable for any use that may be made of the information contained therein. Moreover, because this is an interim result of the project: any conclusions are only preliminary and may change in the course of the project based on further feedback from the contributors, additional collected information and/or increased insight.