How does ventilation impact global energy consumption- EN 15241

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How does ventilation impact global energy
consumption- EN 15241

• Hicham LAHMIDI
• CSTB / Francehicham.lahmidi_at_cstb.fr

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Outline

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

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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

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Brief introduction

• A brief introduction to the CENSE project and the
  CEN-EPBD standards is provided in a separate
  presentation

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More information

• More information and downloads www.iee-cense.eu

Disclaimer CENSE has received funding from the
Communitys 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.
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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

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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

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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

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• 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

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• 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

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

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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.
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Conclusion

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

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More information

• More information and downloads www.iee-cense.eu

Disclaimer CENSE has received funding from the
Communitys 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.