ASSESSING VENTILATIVE COOLING POTENTIAL IN ENERGY PERFORMANCE REGULATIONS STATUS AND PERSPECTIVES IN AUSTRIA, DENMARK, FRANCE

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1 ASSESSING VENTILATIVE COOLING POTENTIAL IN ENERGY PERFORMANCE REGULATIONS STATUS AND PERSPECTIVES IN AUSTRIA, DENMARK, FRANCE Jointly organised by: IEA - EBC Annex 62 project on Ventilative Cooling Venticool ( ) In cooperation with: Air Infiltration and Ventilation Centre ( QUALICHeCK consortium ( CIBSE Natural Ventilation Group (associate partner of venticool) Hosted by: INIVE ( D E P A R T M E N T O F C I V I L E N G I N E E R I N G AALBORG UNIVERSITY I E A E B C AN N E X 6 2 I S AN INTERNATIONAL I E A R E S E A RCH P R OJECT I N I T I A T E D B Y T H E ENERGY I N BUILDINGS A N D C OMMUNITIES P R OGRAMME ( I E A EBC) I N N OVEMBER T H E PROJECT W I L L B E R U N N I N G IN A FOUR YE A R WORKING A N D R E P ORTING PHASE F R OM C OUNTRY P A R T I C I P ATION I N C L U D E S: A U S T R I A, B E L GIUM, C H I N A, D E N M A R K, I R E L A N D, I T A L Y, J A P A N, N E T H E R L ANDS, N ORWAY, P ORTUGAL, SWITZERLAND, UK, USA

2 OBJECTIVES To analyse, develop and evaluate suitable methods and tools for prediction of cooling need, ventilative cooling performance and risk of overheating in buildings that are suitable for design purposes. To give guidelines for integration of ventilative cooling in energy performance calculation methods and regulations including specification and verification of key performance indicators. To extend the boundaries of existing ventilation solutions and their control strategies and to develop recommendations for flexible and reliable ventilative cooling solutions that can create comfortable conditions under a wide range of climatic conditions. To demonstrate the performance of ventilative cooling solutions through analysis and evaluation of well-documented case studies. OUTCOME Guidelines for energy-efficient reduction of the risk of overheating by ventilative cooling Guidelines for ventilative cooling design and operation in residential and commercial buildings Recommendation for integration of ventilative cooling in legislation, standards, design briefs as well as on energy performance calculation and verification methods New ventilative cooling solutions including their control strategies as well as improvement of capacity of existing systems Documented performance of ventilative cooling systems in case studies

3 V E N T I C OOL I S T H E INTERNATIONAL V E N T I L A T I VE COOLING P L A T F ORM L A U N C H E D I N OCTOBER 2012 TO ACCELERATE T H E UPTAKE OF VENTILATIVE COOLING B Y R A I S I N G A W A R E NESS, S H A R I N G E X P E R I ENCE A N D STEERING R E S E ARCH A N D D E V E L OPMENT E F F ORTS IN THE F I E L D OF V E N T I L A T I VE COOLING. T H E SCOPE OF V E N T I C OOL C OVERS A S WELL N A T U R A L, M E C H A N I C AL A N D M I X E D - M ODE VENTILATION. I T S AMBITION IS TO BE THE INTERNATIONAL M E E T I N G POINT F OR VENTILATIVE C OOLING RELATED A C T I V I T I E S. WEBINAR PROGRAMME

4 VENTILATIVE COOLING IN THE DANISH REGULATIONS P E R H E I S E L B E R G D E P A R T M E N T O F C I V I L E N G I N E E R I N G BACKGROUND T H E DEVELOPMENT T OWARDS N E A R Z E R O E N E R GY B U I L D I N GS H A S RESULTED I N A N INCREASED N E E D F OR C OOLING N OT ONLY I N S U M M E R B U T MOST OF THE YE A R! T OO H I GH I N D OOR T E M P E R A T URES ARE T H E MOST R E P ORTED P R OBLEM I N P OST OCCUPANCY S T U D I E S OF THE INDOOR E N V I R ONMENT IN L OW E N E R GY B U I L D I N GS IN D E N M A R K EVEN I N T H E HEATING SEASON! T H E MAIN F OCUS I N T H E DESIGN P R OCES H A S BEEN T O R E D U C E T H E NEED F OR HEATING ( I N S U L A T I ON, AIR TIGHTNESS), B U T T H E R E I S A STRONG N E E D T O A D R E S S C OOLING AS W E L L. B Y U S I N G THE COOLING P OTENTIAL OF OUTDOOR A I R A T T R A C T I V E A N D E N E R GY E F F I C I E N T S OLUTIONS CAN BE D E V E L OPED D E P A R T M E N T O F C I V I L E N G I N E E R I N G AALBORG UNIVERSITY

5 WE HAVE EXPERIENCED AN OVERHEATING PROBLEM OVERHEATING I S A NEW AND INCREASING P R OBLEM F OR LOW E N E R GY R E S I D ENCES Is underestimated and are not given enough focus in the design process T OO S I M P L I F I E D D E S I GN METHODS A R E U S E D Averaging heat loads in time and space Uncertain correlation between cooling need and overheating risk N O (VERY F E W ) A V A I L ABLE S T ANDARD S OLUTIONS E S P E CIALLY F OR RESIDENCES Users have no (very limited) experience in handling overheating One-of-a-kind solutions are often not adapted to practical use D E P A R T M E N T O F C I V I L E N G I N E E R I N G AALBORG UNIVERSITY OVERHEATING D E P A R T M E N T O F C I V I L E N G I N E E R I N G AALBORG UNIVERSITY

6 KOMFORTHUSENE IMPACT OF INTERNAL SOLAR SHADING D E P A R T M E N T O F C I V I L E N G I N E E R I N G AALBORG UNIVERSITY ENERGIPARCEL, TILST, DENMARK D E P A R T M E N T O F C I V I L E N G I N E E R I N G AALBORG UNIVERSITY

7 ENERGIPARCEL RENOVATION EXAMPLES Source: Tine Steen Larsen, Jørgen Søndermark D E P A R T M E N T O F C I V I L E N G I N E E R I N G AALBORG UNIVERSITY ENERGIPARCEL THERMAL COMFORT 2010 Temperatur Living Room Mejløvænget 9 Langøvænget 1 Farøvænget 4 Langøvænget 8 > 26 C (hours) > 27 C (hours) Source: Tine Steen Larsen, Jørgen Søndermark D E P A R T M E N T O F C I V I L E N G I N E E R I N G AALBORG UNIVERSITY

8 VENTILATIVE COOLING IS A SOLUTION V E N T I L A T I VE COOLING CAN B E AN ATTRACTIVE A N D E N E R GY E F F I C I E N T P A S S I VE S OLUTION TO AVOID O V E R H E A T I NG. Ventilation is already present in most buildings through mechanical and/or natural systems using opening of windows Ventilative cooling can both remove excess heat gains as well as increase air velocities and thereby widen the thermal comfort range. The possibilities of utilizing the free cooling potential of low temperature outdoor air increases considerably as cooling becomes a need not only in the summer period. D E P A R T M E N T O F C I V I L E N G I N E E R I N G AALBORG UNIVERSITY VENTILATIVE COOLING IN A DANISH CONTEXT A P P L I C ATION OF VENTILATIVE COOLING F O R R E S I D E NTIAL B U I L D I N GS I S AT A LOW LEVEL It is considered difficult to evaluate Few technical solutions available mainly manual window opening only very few automated V E N T I L A T I VE COOLING IS A STANDARD SOLUTION I N OFFICES W I T H MECHANICAL V E N T I L A T I ON Designed for IAQ criteria Limited benefit due to fan energy use V E N T I L A T I VE COOLING BY N A T U R AL/HYB R I D V E N T I L A T I ON I S K N OWN But only used in a few cases in offices D E P A R T M E N T O F C I V I L E N G I N E E R I N G AALBORG UNIVERSITY

9 VENTILATIVE COOLING IN DANISH BUILDING REGULATIONS D A N I S H B U I L D I N G REGULATION A L L OWS IN GENERAL T E R M S T O T A K E I N T O ACCOUNT T H E EFFECT OF VENTILATIVE C OOLING But does not give any guidelines or recommendations. F OR THERMAL C OMFORT BUILDING REGULATIONS R E F E R T O ISO AND D S 447 But states that air velocities above 0,15 m/s is acceptable if indoor temperature exceeds 24oC Indoor temperature level must not exceed 27C for more than 100 hours/year and 28C for more than 25 hours/year A S I M P L I F I E D M E T H OD IS AVAILABLE T O DOCUMENT COMPLIANCE But as it is based on a mean-monthly approach reliability could be better D E P A R T M E N T O F C I V I L E N G I N E E R I N G AALBORG UNIVERSITY VENTILATIVE COOLING IN DANISH EBPD COMPLIANCE TOOL BE10 T H E DANISH C OMPLIANCE T OOL B E 1 0 I S B A S E D ON A SIMPLIFIED MEAN- M ONTHLY CALCULATION Must be used to document compliance with Danish building regulation Prediction of cooling needs and overheating risk not very accurate V E N T I L A T I VE COOLING IS POSSIBLE T O INCLUDE I N T H E BUILDING E N E R GY P E R F ORMANCE CALCULATION, ALSO FOR NATURAL V E N T I L A T I ON I F YOU A R E V E R Y C L E V ER T H E TOOL ALLOWS YOU TO INPUT VENTILATION R A T E V A L U E F OR V E N T I L A T I VE COOLING SEPARATE D I N D A Y A N D NIGHT VALUES but does not assist you in determining the value Simple to use for mechanical systems, but difficult for natural ventilation. T H E TOOL DOES ESTIMATE THE COOLING NEED ( A V E R A GE F OR W H OLE BUILDING) It is possible to calculate the risk of overheating for a critical room It does not take into account effects of elevated air velocity D E P A R T M E N T O F C I V I L E N G I N E E R I N G AALBORG UNIVERSITY

10 VENTILATIVE COOLING IN DANISH VENTILATION STANDARD DS447 T H E DANISH S T A N D A RD D S 447 SPECIFIES REQUIREMENTS F OR M E C H A N I C AL, N A T U R A L AND H YB R I D VENTILATION S YS T E M S A N D A L S O INCLUDES V E N T I L A TIVE C OOLING EXPRESSED A S Free cooling, Night cooling, Passive cooling, Cooling by means of natural ventilation. Effects of elevated air velocities (informative annex) H OWEVER NO GUIDELINES A R E GIVEN: for system design calculation of cooling performance or how elevated velocities can be achieved and documented D E P A R T M E N T O F C I V I L E N G I N E E R I N G AALBORG UNIVERSITY STATUS OF VENTILATIVE COOLING IN DANISH REGULATORY CONTEXT B U I L D I N G REGULATIONS A N D STANDARDS SUPPORT T H E USE OF V E N T I L A T I VE COOLING, MAINLY I N W ORDS BUT WITHOUT MUCH GUIDANCE T H E DANISH E P B D C OMPLIANCE T OOL D OES NOT SUPPORT A FAIR E V A L U ATION OF VENTILATIVE C OOLING AS PART OF THE C A L C U L ATION P R OCEDURE. S T AT U S ( N A T U R A L ) V E N T I L ATIVE C OOLING I S CONSIDERED S OMEWHAT D I F F I C U L T T O WORK WITH AS DESIGNER OR ENGINEER - T OO L I T T L E GUIDANCE A N D TOO LARGE RESPONSIBILITY. T H E R E F ORE ( N A T U R A L ) V E N T I L ATIVE C OOLING IS NOT WIDELY I N C L U D E D BY B U I L D I N G DESIGNERS. D E P A R T M E N T O F C I V I L E N G I N E E R I N G AALBORG UNIVERSITY

11 FUTURE OF VENTILATIVE COOLING IN DANISH REGULATORY CONTEXT L OOKS PROMISING Increased legislative focus on summer comfort F U T U R E N E E D S Simplified methods for calculating air change rates during nighttime and daytime in buildings with increased ventilation rates (with the purpose of cooling the building). Simplified methods for determining the cooling effect of increased ventilation rates. Control strategies for ventilative cooling based on relevant thermal comfort criteria. D E P A R T M E N T O F C I V I L E N G I N E E R I N G AALBORG UNIVERSITY

12 VENTILATIVE COOLING IN THE AUSTRIAN REGULATORY CONTEXT Dipl.-Ing. Dr. Peter Holzer a. Preventing from Summerly Overheating b. Limiting Technical Cooling Demand a. Preventing from summerly overheating WITHOUT TECHNICAL COOLING, mandatory for all new and significantly renovated residential buildings requirements according to OIB RL 6 (2015) calculation procedure according to ÖNORM B (2012) b. Limiting the technical cooling demand, mandatory for all new and significantly renov. non residential buildings requirements according to OIB RL 6 (2015) calculation procedure according to ÖNORM B (2012) together with ÖNORM H 5057 (2011)

13 Requirements according to OIB RL 6 (2015) Residential houses obligatorily have to offer summerly comfort without technical cooling, proven by simplified dynamic (hourly) energy balance against standardized climate and standardized usage patterns. Night Ventilation definitvely may be included. Non residential houses obligatorily have to keep within the limits of the net cooling demand, defined as the outside induced cooling demand, proven by monthly energy demand calculation. Night Ventilation may be included. a. National Code B (2012) Thermal protection in building construction Part 3: Avoidance of summerly overheating

14 Background and Scope of Application Part of the OENORM B 8110 series Thermal protection in building construction Revised and relaunched in March 2012 Valid for all types of rooms with constant human occupancy, without technical cooling Definition of Summer Comfort Max. 27 C operative Temperature in each room Max. 25 C operative Temperature in sleeping rooms at night both on a statistically hot, mid-july, clear summer s day, occuring in infinite periodic repetition

15 Calculation Procedure: Dynamic Heat Balance acc. to EN ISO Input parameters Climate Geometry Thermal Properties Solar properties, including shading Internal load profiles Ventilation Calculation Procedure Input parameters Climate Geometry Thermal Properties Solar properties, including shading Internal load profiles Ventilation Site sensitive, hourly climate data, defined as a constantly repeated, mid summer s design day (obligatory) to be taken from OENORM B , defined by the mean day temp of 15. July plus an hourly defined day/night swing of 7K further referring to EN (sky temp.) EN ISO (ground temp.)

16 Calculation Procedure Input parameters Climate Calculation Procedure Input parameters Climate Geometry Thermal Properties Solar Properties, including Shading Internal Load Profiles Ventilation Orientation sensitive input of the building s / room s envelope and volume

17 Calculation Procedure Input parameters Climate Geometry Thermal Properties Solar Properties, including Shading Internal Load Profiles Ventilation U-Values of both opaque and transparent building elements including U-values, density, specific heat, conductivity usable termal mass calculated according to simplified method of EN Calculation Procedure Input parameters Climate Geometry Thermal Properties Solar Properties, including Shading Internal Load Profiles Ventilation g-values (SHGC) of transparent layers according to manufacturers information Fc values (shading coefficients) of blinds according to EN additionally referring to EN and EN and EN (wind resistance) EN (fixed obstacles)

18 Calculation Procedure Input parameters Climate Geometry Thermal Properties Solar Properties, including Shading Internal Load Profiles Ventilation Mandatory lists of hourly internal load profiles and hygienic ventilation rates for residential buildings, office buildings, schools and hospitals, given in [W/m²], [W/workplace], [m³/h,pers] Calculation Procedure Internal Load Profile, exemplary for residential use

19 Calculation Procedure Input parameters Climate Geometry Thermal Properties Solar Properties, including Shading Internal Load Profiles Ventilation Window ventilation by formula, V [m³/h] = f(a w, H w, T) Mechnical ventilation up to 1,5 ACH in occupied rooms and up to 2,5 ACH in unoccupied rooms, taking into account the thermal load from vents Ventilative Cooling by Window Opening with C ref Discharge Coefficient C ref = 100 m 0,5 /(h.k 0,5 )

20 Ventilative Cooling by Window Opening with C ref = 300 m 0,5 /(hk 0,5 ) with Ventilative Cooling by Window Opening W = 40 cm H = 120 cm

21 Exemplary Outputs taken from a specific residential room, comparing the effects of three different wall types, Holzer 2013 Learnings ÖNORM B :2012 offers a well applicable method of evaluating the risk of summerly overheating, for rooms without mechanical cooling. Effects of Ventilative Cooling can be taken into account both for mechanical and for window-based solutions. The physical principle of a periodically repeated dynamic heat balance leads to robust and highly comparable outputs, given in a daily run of the room s operative temperature.

22 Learnings Commercial simulation software products usually aren t prepared to calculate the air flow through windows exactly according to formula (1). The calculation model isn t well prepared for stack effect ventilation. The method of periodically repeated dynamic heat balance isn t sensitive to transient effects of heat storage during heat waves of limited duration. Learnings As regards the scope of the code, it s still is a point of discussion, how to define the summer performance of buildings with thermal mass activation but without Air- Conditioning: By definition they are mechanically cooled. By perception they are very much anticipated as free running mode buildings.

23 b. National Code B (2014) Thermal protection in building construction Part 6: Principles and verification methods Heating demand and cooling demand National application, national specifications and national supplements to ÖNORM EN ISO Background and Scope of Application Valid for all types of buildings with constant human occupancy, WITH technical cooling Limiting the outside induced net cooling demand KB* 1 kwh/m³a (newly built) KB* 2 kwh/m³a (major renovation) calculated by monthly energy balance against monthly mean outside temperature and mandatory 26 C inside temperature

24 Calculation Procedure Calculation Procedure

25 Calculation Procedure -20% +100% +10% +100% +100% +50% 1,5 ACH 8 h/d Conclusion ÖNORM B : 2014 offers a simplified method of taking into account night ventilation / Ventilative Cooling both for mechanical and for window-based solutions. Resulting in a reduction of the outside induced cooling demand in the exemplary range of 20%, ofering an object to optimization.

26 Thank you! Dipl.-Ing. Dr. Peter Holzer

27 Assessing ventilative cooling potential in Energy Performance regulations Webinar 2015/12/08 Ventilative cooling in the French Regulation. Charles PELE

28 French regulations RT2012 : French thermal regulation Energy needs Energy used Summer comfort ort Bbio < Bbio max On average, Cep < 50 kwh/m².year Tic < Tic Ref 3 French regulations / ventilation Residential building : Decree of March 1982 : Aeration of the housing must be general and permanent at least during the period when the outside temperature requires to keep the windows closed. Other buildings : minimum air flow rate depending on the type of buildings RT

29 Natural ventilation strategy 1- Empirical model for monozone is usued at each time step (1 hour) = 1800; C 1 = 0.001; C 2 1; C 3 = ; h: height of the opening ; 2 - Aouv: depending on the external temperature, the internal external temperature difference and the type of windows. 3 - COMETh : COre for Modeling Energy and THermal comfort Q v T op 5 Example House in the south of France, ( 150m²; 1 level ) 6

30 Mechanical ventilation Timer Night refresh 7 Mechanical ventilation The windows are open The extra flow rate is on mode Without extra ventilation extra ventilation consumption 8 kwhep/m².y 10,7 kwhep/m².y 8

31 Conclusion Ventilative cooling i.e., the use of natural or mechanical ventilation strategies to cool indoor spaces is already implemented in the French thermal regulation RT 2012, both for residential buildings and for commercial buildings. Opening windows and night mechanical ventilation allow to reduce indoor temperatures and to maintain a comfortable thermal environment. This allows to delay the startup of air-conditioning systems. On cases presented and with our hypotheses, opening windows seems more effective and it does not consume energy. 9 Merci pour votre attention

32 RT Bibliography JB Videau and al; An Introduction to the Development of the French Energy Regulation Indicators and Their Calculation Methods ; Clima 2013 B. Haas and al ; Etudes de sensibilité avec COMETH ; IBPSA 2013; MEEDDM, Arrêté du 26 octobre 2010 relatif aux caractéristiques thermiques et aux exigences de performance énergétique des bâtiments nouveaux et des parties nouvelles de bâtiments MEEDDM, Arrêté du 20 juillet 2011 portant approbation de la méthode de calcul Th-B-C-E, Ventilative Cooling State of the art, IEA EBC Programme Annex 62 Ventilative Cooling, Edited by Maria Kolokotroni and Per Heiselberg 11