VENTILATIVE COOLING 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

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1 VENTILATIVE COOLING P E R H E I S E L B E R G

2 Residential Buildings

3 WHY DO WE EXPERIENCE AN OVERHEATING PROBLEM IN HIGH PERFORMANCE BUILDINGS? OVERHEATING I S A N I N C R E A SING P R OBLEM FOR LOW ENERGY R E S I D E NCES Is underestimated and are not given enough focus in the design process Compliance with energy use is documented not indoor environment TOO S I M P L I F I E D D E S I G N 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 FOR RESIDENCES Users have no (very limited) experience in handling overheating One-of-a-kind solutions are often not adapted to practical use

4 WHY DO WE EXPERIENCE AN OVERHEATING PROBLEM IN HIGH PERFORMANCE BUILDINGS? I T IS NOT POSSIBLE T O REACH GOALS THROUGH MORE Envelope insulation, Building airtightness, Ventilation heat recovery, W H I C H ARE R OBUST T E C H N OLOGIES W I T H OUT USER I N T E R A C T I ON N E W MEASURES N E E D S T O BE I N C L U D E D Demand controlled ventilation Shading for solar energy control Shading for daylighting control Lighting control Window opening A L L TECHNOLOGIES: Where performance is very sensitive to control Which involve different degree of user interaction Whose function and performance are difficult for users to understand

5 ENERGY RENOVATION ENERGIPARCEL, TILST, DENMARK

6 ENERGIPARCEL RENOVATION EXAMPLES Source: Tine Steen Larsen, Jørgen Søndermark

7 ENERGIPARCEL OVERHEATING 2010 Temperatur Living Room Mejløvænget 9 Langøvænget 1 Farøvænget 4 Langøvænget 8 > 26 C (hours) > 27 C (hours) Reference: Tine Steen Larsen, Aalborg University and Jørgen Søndermark, Realdania Byg

8 ENERGY RENOVATION AND OVERHEATING IN TYPICAL HOUSING IN CENTRAL/NORTH EUROPE A U S T R I A Area 144 m 2 Ref. 2 D E N M A R K Area 118 m 2 Ref. 1 F R A N C E Area 116 m 2 Ref. 1 U N I T E D K I N GDOM Before 1978 Area 80 m 2 Ref TABULA project web tool, Retrieved from (September, 2014). 2. Österreichisches Institut für Bautechnik, 2013, "Dokument zum Nachweis der Kostenoptimalität der Anforderungen der OIB-RL6 bzw. des Nationalen Plans gemäß Artikel 4 (2) zu 2010/31/EU." Austria. 3. Department for Communities and Local Government, 2013, "Energy Performance of Buildings Directive (recast). Cost optimal calculations: UK report to European Commission". U.K

9 SELECTED RENOVATION MEASURES W I N D OWS RETROFIT (REGULATIONS A N D N Z E B / P H S T A N D A RD) + C E I L I N G RETROFIT (REGULATIONS A N D N Z E B / P H S T A N D A RD ) + + E X TERNAL W A L L RETROFIT (REGULATIONS A N D N Z E B / P H S T A N D ARD) F L OOR RETROFIT (REGULATIONS AND N Z E B / P H S T A N D A RD) A I R T I GHTNESS IMPROVEMENT (REGULATIONS A N D NZEB/PH S T A N D A RD)

10 THERMAL CHARACTERISTICS FOR REFERENCE CASES AND DIFFERENT RENOVATION LEVELS a/a Reference period Uwall (W/m²K) Uceiling (W/m²K) Ufloor (W/m²K) Uwin/g (W/m²K) n50 (ach) Austria Base After / Renovation / nzeb / Denmark Base / Renovation /2015/ / / /0.8 France Base / Renovation / nzeb / UK Base Before / Renovation / nzeb / Number of Storey (semi detached) Source Cost-Optimal report TABULA Cost-Optimal report/tabula Cost-Optimal report

11 RENOVATION CASE - AUSTRIA Regulations NZEB/PH

12 RENOVATION CASE - DENMARK Regulations NZEB/PH

13 PERCENTAGE OF OVERHEATING HOURS FOR DIFFERENT VENTILATION FLOW RATES - DENMARK PHASES 1. Reference 2. Regulation 3. NZEB/PH

14 PERCENTAGE OF OVERHEATING HOURS FOR DIFFERENT SHADING STRATEGIES - DENMARK PHASES 1. Reference 2. Regulation 3. NZEB/PH

15 DENMARK Danish case study, TABULA project

16 FRANCE Case study for South France, TABULA project

17 TUEN, BIRKERØD, DENMARK - TEST OF CONTROL AND USER INTERACTION

18 SUMMARY OVERHEATING I S A N ISSUE T H A T S N E E D S T O BE A D D R E SSED I N B OTH NEW H I GH PERFORMING RESIDENTIAL B U I L D I N GS A S W E L L A S IN DEEP R E N OVATIONS S OLAR SHADING A N D V E N T I L A T I VE COOLING ARE S U S T A I N ABLE M E A S U R ES T H A T ARE A B L E R E D U C E OVERHEATING R I S K EXPECTED P E R F ORMANCE W I L L BE REDUCED I N P R A C T I C E D U E TO USER OVERRIDE I M P R OVED C ONTROL STRATEGIES ( P A R T L Y A U T OMATIC) AND U S E R GUIDANCE W I L L REDUCE T H E DISCREPANCY B E T W E E N E X P E CTATIONS A N D PRACTICE

19 Office Buildings

20 COOLING IN OFFICES AND EDUCATIONAL BUILDINGS W I T H HIGH INSULATION A N D AIR TIGHTNESS L E V E L S A L W A YS A C OOLING NEED D U R I N G OCCUPIED H OURS EVEN I N T H E W I N T E R S E A S ON C OOLING IS NOT A NEW T E C H N OLOGY, B U T T H E NEED F OR C OOLING IS INCREASING A N D M ORE EFFICIENT S YS T E M S H A V E T O B E DEVELOPED TO FULFILL FUTURE E NERGY REQUIREMENTS A P P L I C ATION OF THE F R E E C OOLING P OTENTIAL OF OUTDOOR AIR I S W I D E L Y USED I N M E C H A N I CAL V E N T I L A T I ON S YS T E M S, B U T H I GH AIR FLOW RATES A R E N E E D ED I N W I N T E R B E C A U SE OF D R A U GHT R I S K L E A D I N G TO RELATIVELY HIGH ENERGY U S E F OR A I R TRANSPORT

21 WHAT IS DIFFUSE CEILING VENTILATIO N THE SPACE A B OVE A S U S P ENDED C E I L I N G IS USED A S A PLENUM A N D F R E S H A I R IS SUPPLIED T O THE OCCUPIED Z ONE THROUGH P E R F ORATED S U S P E NDED C E I L I N G.

22 THE PRINCIPLE Rockfon / Troldtekt ceiling Ecophon ceiling Fully diffuse ceiling

23 VENTILATIVE COOLING OFFICES IN COLD CLIMATE

24 WIDEX/WESSBERG A/S

25 SOLBJERGSKOLEN SOUTHWEST OF ÅRHUS

26 SYSTEM PRINCIPLE

27 DRAUGHT RISK Extreme winter condition: supply air temperature -8 o C, ACH =4 DR <20% ISO 7730

28 CONCLUSION Low draught risk in the occupied zone even, when supplying air at temperatures below 0C o Air distribution and draught risk dependent on heat load location, ceiling height, area and location of supply. Very low vertical temperature gradient in the room with diffuse celling supply Low radiant temperature asymmetry and no clear radiation cooling potential of diffuse ceiling, due to low conductivity Very low pressure drop across diffuse ceiling (less than 5 Pa)

29 Per Heiselberg Aalborg University Thanks for your attention

30 The sole responsibility for the content of this presentation lies with the authors. It does not necessarily reflect the opinion of the European Union. Neither the EASME nor the European Commission are responsible for any use that may be made of the information contained therein.