Ventilation for buildings - Calculation methods for energy losses due to ventilation and infiltration in buildings

This European Standard describes the method to calculate the energy impact of ventilation systems (including airing) in buildings to be used for applications such as energy calculations, heat and cooling load calculation.
Its purpose is to define how to calculate the characteristics (temperature, humidity) of the air entering the building, and the corresponding energies required for its treatment and the auxiliaries electrical energy required.
This standard can also be used for air heating and cooling systems when they assure the provision of ventilation, considering that prEN 15243 will provide the required heating or cooling load and the corresponding air flows and/or air temperatures.

Lüftung von Gebäuden - Berechnungsverfahren für den Energieverlust aufgrund der Lüftung und Infiltration in Gebäuden

Diese Europäische Norm beschreibt das Verfahren zur Berechnung der energetischen Auswirkungen von Lüftungsanlagen (einschließlich Fensterlüftung) in Gebäuden, das z. B. bei Energieberechnungen und Heiz  und Kühllastberechnungen anzuwenden ist.
Der Zweck besteht darin, festzulegen, wie die Kennwerte (Temperatur, Luftfeuchte) der in das Gebäude eintretenden Luft und die entsprechenden für ihre Behandlung erforderlichen Energien und elektrische Hilfsenergie zu berechnen sind.
Diese Norm kann auch auf Lufterhitzer und  kühler angewendet werden, wenn sie die Lüftung sicherstellen, wobei zu berücksichtigen ist, dass die geforderte Heiz  bzw. Kühllast und die entsprechenden Luft¬volumen¬ströme und/oder Lufttemperaturen in prEN 15243 festgelegt werden

Ventilation des bâtiments - Méthodes de calcul des pertes d'énergie dues a la ventilation et a l'infiltration dans les bâtiments

La présente Norme européenne décrit la méthode de calcul de l’impact énergétique des systemes de ventilation (y compris l’aération) dans les bâtiments, utilisée pour des applications telles que les calculs d’énergie et le calcul de la charge de chauffage et de refroidissement.
La présente norme vise a définir les méthodes de calcul des caractéristiques (température, humidité) de l’air entrant dans le bâtiment, et les énergies correspondantes requises pour le traitement de cet air et les énergies requises par les auxiliaires électriques.
La présente norme peut également etre utilisée pour les systemes de refroidissement et de chauffage de l’air lorsqu’ils assurent la ventilation, sachant que le prEN 15243 fournira les charges de refroidissement et de chauffage exigées et les températures d’air et/ou les débits d’air correspondants.

Prezračevanje stavb - Računske metode za energijske izgube zaradi prezračevanja in infiltracije v stavbah

General Information

Status
Withdrawn
Publication Date
16-Sep-2007
Withdrawal Date
11-Jun-2018
Technical Committee
Current Stage
9900 - Withdrawal (Adopted Project)
Start Date
17-May-2018
Due Date
09-Jun-2018
Completion Date
12-Jun-2018

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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Lüftung von Gebäuden - Berechnungsverfahren für den Energieverlust aufgrund der Lüftung und Infiltration in GebäudenVentilation des bâtiments - Méthodes de calcul des pertes d'énergie dues a la ventilation et a l'infiltration dans les bâtimentsVentilation for buildings - Calculation methods for energy losses due to ventilation and infiltration in buildings91.140.30VLVWHPLVentilation and air-conditioningICS:Ta slovenski standard je istoveten z:EN 15241:2007SIST EN 15241:2007en01-oktober-2007SIST EN 15241:2007SLOVENSKI

STANDARD

EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 15241May 2007ICS 91.140.30 English VersionVentilation for buildings - Calculation methods for energy lossesdue to ventilation and infiltration in commercial buildingsVentilation des bâtiments - Méthode de calcul des pertesd'énergie dues à la ventilation et aux infiltrations dans lesbâtiments commerciauxLüftung von Gebäuden - Berechnungsverfahren für denEnergieverlust aufgrund der Lüftung und Infiltration inNichtwohngebäudenThis European Standard was approved by CEN on 26 March 2007.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the CEN Management Centre or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as theofficial versions.CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36

B-1050 Brussels© 2007 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 15241:2007: E

EN 15241:2007 (E) 2 Contents Page Foreword.............................................................................................................................................................3 1 Scope......................................................................................................................................................6 2 Normative references...........................................................................................................................6 3 Terms and definitions...........................................................................................................................6 4 Symbols and abbreviations.................................................................................................................7 5 General approach..................................................................................................................................8 6 Steady state calculation.......................................................................................................................9 6.1 Basis of the calculation method..........................................................................................................9 6.2 Air entering through infiltration, passive air inlets or windows......................................................9 6.3 Air entering through balanced or supply only system calculation.................................................9 6.3.1 General...................................................................................................................................................9 6.3.2 Duct heat losses..................................................................................................................................10 6.3.3 Duct flow losses..................................................................................................................................10 6.3.4 Fan........................................................................................................................................................10 6.3.5 heat exchanger....................................................................................................................................13 6.3.6 Mixing boxes.......................................................................................................................................15 6.3.7 Pre-heating..........................................................................................................................................16 6.3.8 Pre-cooling..........................................................................................................................................16 6.3.9 Humidifying in winter..........................................................................................................................17 6.3.10 Dehumidification.................................................................................................................................17 7 Implementation of the method...........................................................................................................18 7.1 General.................................................................................................................................................18 7.2 Hourly method.....................................................................................................................................18 7.3 Monthly methods................................................................................................................................19 7.3.1 System with no or low humidity impact...........................................................................................19 7.3.2 System with medium or high humidity impact................................................................................19 7.4 Statistical approach to be applied at national level........................................................................20 Annex A (informative)

A simplified model of a Ground to Air Heat Exchanger.........................................21 A.1 Background and summary.................................................................................................................21 A.2 Overview of program links, variables, parameters and constants................................................22 A.3 Physical description of the ground to air heat x-change model....................................................23 Bibliography.....................................................................................................................................................26

EN 15241:2007 (E) 3 Foreword This document (EN 15241:2007) has been prepared by Technical Committee CEN/TC 156 “Ventilation for buildings”, the secretariat of which is held by BSI. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by November 2007, and conflicting national standards shall be withdrawn at the latest by November 2007. This standard has been prepared under a mandate given to CEN by the European Commission and the European Free Trade Association (Mandate M/343), and supports essential requirements of EU Directive 2002/91/EC on the energy performance of buildings (EPBD). It forms part of a series of standards aimed at European harmonisation of the methodology for the calculation of the energy performance of buildings. An overview of the whole set of standards is given in CEN/TR 15615, Explanation of the general relationship between various CEN standards and the Energy Performance of Buildings Directive (EPBD) ("Umbrella document"). Attention is drawn to the need for observance of relevant EU Directives transposed into national legal requirements.

Existing national regulations with or without reference to national standards, may restrict for the time being the implementation of the European Standards mentioned in this report According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.

EN 15241:2007 (E) 4 Introduction This standard defines the way to calculate the energy impact of airflows due to the ventilation system. Ventilation system impact is calculated as direct (energy devoted to the air treatment and move in the ventilation system), and indirect (impact on cooling and heating of the building). The relationships with some other standards are as follows:

Figure 1 - Scheme of relationship between standards Table 1 - Relationship between standards from To

Information transferred variables 15251 15243 Indoor climate requirements
Heating and cooling Set points

13779 15251 15242 Airflow requirement for comfort and health Required supply and exhaust Air flows 15242 15241 Air flows Air flows entering and leaving the building 15241 13792 Air flows Air flow for summer comfort calculation 15241 15203- 15315 ;15217 energy Energies per energy carrier for ventilation (fans, humidifying, precooling, pre heating), + heating and cooling for air systems 15241 13790 data for heating and cooling calculation Temperatures, humilities and flows of air entering the building 15243 15243 Data for air systems Required energies for heating and cooling

15243 15242 Data for air heating and cooling systems Required airflows when of use 15243 13790 data for building heating and cooling calculation Set point, emission efficiency, distribution recoverable losses, generation recoverable losses 13790 15243 Data for system calculation Required energy for generation

EN 15241:2007 (E) 5 EN titles are: prEN 15217, Energy performance of buildings — Methods for expressing energy performance and for energy certification of buildings prEN 15603, Energy performance of buildings — Overall energy use and definition of energy ratings prEN 15243, Ventilation for buildings — Calculation of room temperatures and of load and energy for buildings with room conditioning systems prEN ISO 13790, Thermal performance of buildings — Calculation of energy use for space heating and cooling (ISO/DIS 13790:2005) EN 15242, Ventilation for buildings — Calculation methods for the determination of air flow rates in buildings including infiltration EN 15241, Ventilation for buildings — Calculation methods for energy losses due to ventilation and infiltration in commercial buildings EN 13779, Ventilation for non-residential buildings — Performance requirements for ventilation and room-conditioning systems EN 13792, Colour coding of taps and valves for use in laboratories EN 15251, Indoor environmental input parameters for design and assessment of energy performance of buildings addressing indoor air quality, thermal environment, lighting and acoustics The target audience of this standard is policy makers in the building regulation sector, software developers of building simulation tools, industrial and engineering companies.

EN 15241:2007 (E) 6 1 Scope This European Standard describes the method to calculate the energy impact of ventilation systems (including airing) in buildings to be used for applications such as energy calculations, heat and cooling load calculation. Its purpose is to define how to calculate the characteristics (temperature, humidity) of the air entering the building, and the corresponding energies required for its treatment and the auxiliaries electrical energy required. This standard can also be used for air heating and cooling systems when they assure the provision of ventilation, considering that prEN 15243 will provide the required heating or cooling load and the corresponding air flows and/or air temperatures. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 12792:2003, Ventilation for buildings — Symbols, terminology and graphical symbols EN 13053:2006, Ventilation for buildings — Air handling units — Rating and performance for units, components and sections EN 13779, Ventilation for non-residential buildings — Performance requirements for ventilation and room-conditioning systems prEN 15232, Energy performance of buildings — Impact of Building Automation, Controls and Building Management EN 15242, Ventilation for buildings — Calculation methods for the determination of air flow rates in buildings including infiltration prEN 15243, Ventilation for buildings — Calculation of room temperatures and of load and energy for buildings with room conditioning systems prEN ISO 13790, Thermal performance of buildings — Calculation of energy use for space heating and cooling (ISO/DIS 13790:2005) 3 Terms and definitions For the purposes of this document the terms and definitions given in EN 12792:2003 and the following apply. 3.1 defrosting coil coil used before the heat exchanger to prevent its frosting 3.2 pre-heating coil coil used to warm up the air entering the supply ducted system to a predefined value (e.g.; not controlled according to indoor temperature) 3.3 pre-cooling coil coil used to cool down the air entering the supply ducted system to a predefined value

EN 15241:2007 (E) 7 3.4 building height height of the building from the entrance ground level to the roof top level 3.5 building leakage overall leakage airflow for a given test pressure difference across building 3.6 building volume volume within internal outdoor walls of the purposely conditioned space of the building (or part of the building). This generally includes neither the attic, nor the basement, nor any additional structural annex of the building 3.7 building air temperature average air temperature of the rooms

4 Symbols and abbreviations Table 2 — symbols and abbreviations Symbol Unit descriptionA m² area Bh m building height Cductleak ad coefficient taking into account lost air due to duct leakages Csyst ad coefficient taking into account the component and system design tolerances Cuse ad coefficient taking into account the switching on and off of fans Ccont ad coefficient depending on local air flow control Eff ad efficiency H W/K heat loss qv(dP) curve or airflow/pressure difference characteristic

formula

qv 4Pa,n or m3/h external enveloppe airtightness expressed as an airflow for a given pressure n50,n

difference, exponent qv 4Pa,n or m3/h partial air tightnesss for altitude (z), orientation (or), tilt angle (Tilt) n50,n

qv-exh m3/h exhaust air flow

qv-sup m3/h supply air flow P W heating power R Ad ratio θ °C temperature x g/kg of dry air moisture content of the air

EN 15241:2007 (E) 8 Table 3 — Indices used in the documents sup Concerns supply air as defined in EN 13779 rec Concerns recirculation exh Concerns exhaust air as defined in EN 13779 ductsurr Concerns air surrounding the duct e1 Concerns exhaust air entering unit e2 Concerns exhaust air at unit’s exit s1 Concerns supply air entering unit s2 Concerns supply air at unit’s exit PC Concerns precooling PH Concerns pre-heating hum Concerns humidifying Fan or f Concerns fan HE Concerns heat exchanger f,r Concerns heat recovered from fan ext external int internal duct Concerns the duct cont control

5 General approach EN 15242 defines the procedure to calculate the following air flows (either entering or leaving the heated/conditioned area) through leakages, opened windows, purpose provided openings (considered as part of the ventilation system) and the ventilation system. For overall heating and cooling needs calculation, prEN ISO 13790, uses directly the airflows entering the building through leakages, opened windows, and purpose provided opening, as there's is no additional energy impact when these air flows are known. Therefore this standard focuses on the impact on the ventilation system itself both for the air treatment and move. For air heating and cooling system, prEN 15243 provides the required airflow and supply temperatures.

23415 Key 1 ventilation system 4 leakage 2 window opening 5 internal reference pressure 3 opening

Figure 2 — general scheme for airflows

EN 15241:2007 (E) 9 The ventilation system here considered does not directly include room controlled heating and cooling, but only preheating and precooling coils. The local heating or cooling system description and calculation is not considered directly. Its possible impact on the exhaust air temperature or on the required airflows set points and controls can nevertheless be taken into account. The aim of this standard is therefore to provide the "air information" for heating and cooling calculation methods, which means:  Air flows (from standard EN 15242), temperature, humidity entering the heated/conditioned area both for ventilation and infiltration.  Electrical needs for fan and ventilation system auxiliaries;  Required energy for defrosting,

preheating, precooling, humidifying, dehumidifying;  The heating and cooling energy needs due to infiltration are not part of the standard. Required energy for heating and cooling for air heating and cooling systems can be taken into account using the same formulas in connection with prEN 15243. These energies will be provided by energy carrier and use (heating, cooling, ventilating). In some cases it will require some specific assumptions as for example if a fan is used for ventilation, heating and cooling.

Three implementation possibilities of the calculation procedure described in Clause 6 are shown in Clause 7.

6 Steady state calculation 6.1 Basis of the calculation method Starting from the airflows, the aim of the procedure is to calculate:  Temperature and humidities of the airflows entering the heated or cooled areas.  Energy devoted to the air treatment. 6.2 Air entering through infiltration, passive air inlets or windows It is basically considered that the air characteristics are the outdoor air ones.

Preheated air inlets and ground coupling are part of this standard If the air is taken in an adjacent space the air temperature in this space shall be calculated according to prEN ISO 13790. 6.3 Air entering through balanced or supply only system calculation 6.3.1 General The following subclauses describe how the air characteristics are modified in each component, and the energy required for that treatment.

EN 15241:2007 (E) 10 6.3.2 Duct heat losses 6.3.2.1 Heat transfer through the parts of duct situated in the heated/conditioned area It has to be evaluated if these losses are significant in respect to the accuracy required for the calculations. They can be neglected for systems not providing heating and cooling. If not the equations are the same as if the ducts are situated out of the conditioned area but the air temperature surrounding the duct is equal to the zone temperature. If the heat transfer of the zone to the air in the duct is taken into account, the energy balance of the room shall be completed (e.g. the heat transfered to the air shall be lost by the zone). 6.3.2.2 Heat transfer through the parts of duct situated out the heated/conditioned area The air temperature is modified in the duct as follows: θ2 = θ1 + ∆Tduct x2 = x1 where

∆Tduct

is the difference in air temperature between the inlet and the outlet of the duct, in K θ1,x1

are the air temperature and humidity at the inlet of the duct, (in °C and g/kg of dry air) θ2,x2

are the air temperature and humidity at the outlet of the duct, (in °C and g/kg of dry air) ∆Tduct

is calculated by
)1)(().34,0(1vductductqHsurductducteT−−−=∆θθs where
θsurduc

is the temperature of the air surrounding the duct, equal in this case to the outdoor air temperature, in °C Hduct

is the heat loss from the duct to the surrounding, in W/K
qvduct
is the rate of air flow in the duct, in (m³/h)

6.3.3 Duct flow losses The infiltred or exfiltred flow into or from the duct is calculated according to EN 15242. If the air is exfiltred, there is no change in air characteristics in the duct (but a difference in air flows). If the air is infitred, the outdoor air is mixed to the air entering the duct. 6.3.4 Fan

The air temperature is increased by the fan of a ∆Tfan
value
EN 15241:2007 (E) 11 vfanrf,fan...qcRFTfanρ=∆
where: ∆Tfan
is the increase of air temperature caused by fan, in K, Ffan
is the fan power, in W, Rf,r
is the fan power recovered ratio (ad.), ρ c
is the product of the air density and the specific heat, in 34 W
...

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