The document summarizes an overheating assessment of a Passive House case study in Spain. Monitoring was conducted over a year to evaluate overheating risks using several methods: ISO 7730 found 10% of hours too hot; EN 15251 found 0.2% too hot; CIBSE TM52 found no exceedances; and Passivhaus standard found 11.8% of hours over 25C, not meeting its criteria. While conclusions varied, all methods provided useful insights. Recommendations include evaluating overheating separately in different zones, improving shading, and considering occupancy variations in future assessments.

1. University of the
Basque Country LABORATORY FOR THE QUALITY CONTROL
IN BUILDINGS, BASQUE GOVERNMENT
Overheating Assessment of a
Passive House Case Study in Spain
Juan María Hidalgo*, Theofanis Psomas, Carlos García-Gáfaro,
Per Heiselberg, Jose Antonio Millán
36th AIVC Conference
5th TightVent Conference
3rd veticool Conference
Effective ventilation in high performance buildings
23 – 24 September 2015
Madrid, Spain

2. Overheating Assessment of a Passive House Case Study in Spain
36th AIVC Conference. Effective ventilation in high performance buildings.
0. Teamwork
• University of the Basque Country UPV/EHU
– Laboratory for the Quality Control in Buildings, Basque Government
– ENEDI Research Group
– Department of Thermal Engineering
• Aalborg University, AAU
– Department of Civil Engineering
– Strategic Research Center on Zero Energy Buildings
2
ENERGY IN BUILDINGS

3. Overheating Assessment of a Passive House Case Study in Spain
36th AIVC Conference. Effective ventilation in high performance buildings.
1. Problem overview
• European regulation requirements:
– Oriented to reduce the heating losses to a minimum.
– More insulated and airtight buildings
• International warnings about Global warming:
– The Intergovernmental Panel on Climate Change (IPCC) warned in 2013
about increases in temperature of more than 4 ºC by the end of the century.
– The Zero Carbon Hub (ZCH) published a OH report in 2010, in Great Britain.
• Overheating definition (OH):
– No specific regulation in Spain and many other countries to prevent OH.
• Mainly based in Thermal Comfort approach: Fanger or Adaptive methods.
– CIBSE TM52 stated in 2013:
“overheating implies that building
occupants feel uncomfortably hot and that
this discomfort is caused by the indoor
environment”
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4. Overheating Assessment of a Passive House Case Study in Spain
36th AIVC Conference. Effective ventilation in high performance buildings.
2. Objective of the study
• Assess the overheating risk in a single family Passive House.
– Compare the different methodologies and their applicability to OH risk detection.
– Check the best periods to detect OH risk.
– Check the different room conditions
4
CIBSE TM52

5. Overheating Assessment of a Passive House Case Study in Spain
36th AIVC Conference. Effective ventilation in high performance buildings.
3. Case Study description: Building main features
 Motivated by some complains of the inhabitants about TC.
 175 m2, heating demand of 14 kWh/m2y (PHPP calculations)
 High insulated envelope, thermal bridges checked by IR.
 n50 less than 0,30 renovations per hour.
 MVHR with a measured seasonal performance of 86 %.
5
Project by CLIM Estudio de Arquitectura SLP
Construction work by Construcciones Urrutia SL

6. Overheating Assessment of a Passive House Case Study in Spain
36th AIVC Conference. Effective ventilation in high performance buildings.
3. Case Study description: Monitored parameters and sensor position
Pc13: Electric Heating power.
Ca13: Indoor Thermal Confort
Tc13: Pellet heater T.
Hr13: Air Relative Humidity
F06: Facade Heat Flux meter
Te61: Facade outdoor surface Temperatures
Tp21: Pillar surface Temperature
Tfs01: Floor and ceiling surface Temperatures
Ta13: Air Temperature
Ts0102: Partition surface Temperature
Room number
Long monitoring period: 4 Feb 2013 – 13 April 2014
 High accuracy measurements
 Indoor air conditions in rooms and stratification.
 Heating demand measurement by electric heaters
 Facade in-situ measurement of thermal resistance and thermal
transmittance, ISO 9869.
 Thermal Comfort measured in spring, summer and winter weeks.
 MVHR distribution measures and improvements.
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7. Overheating Assessment of a Passive House Case Study in Spain
36th AIVC Conference. Effective ventilation in high performance buildings.
3. Case Study description: Building Energy Monitoring System
Meteorología
Ambiente
interior
Cerramientos
Calefacción
Ventilación
T. aire, H.R., Presión,
Viento, Radiación
T. aire, H.R.
T.Superficial, Flujo de
calor
T.aire, Potencia
Caudal, Recuperación
de calor
Usuarios
Calefacción,
Ventilación, actividad
Seguimiento
Post-procesado y
resultados
Análisis y
conclusiones
Almacenamiento
de datos
Adquisidor
de datos
USB
230V
SAI
Internet
CorreccionesEdificio Pasivo
Outdoor Air T. RH,
pressure, etc
Indoor Air T. RH.
Facade surface T,
heat flux
Heater power
MV - Heat Recovery
rate
Heating & ventilation
configuration
Local Weather
Thermal comfort
Bd Envelope
Heating
Ventilation
User behaviour
Passive Bd.
Data backup
Data logger
Monitoring
Data processing
and results
Analysis and
model comparison
UPS
Feedback and Fixes
7
 Long monitoring period: 4 Feb 2013 – 13 April 2014
 High accuracy measurements
Short time-step of 1 min, averaged to 1 hour

8. Overheating Assessment of a Passive House Case Study in Spain
36th AIVC Conference. Effective ventilation in high performance buildings.
4. Overheating detection models and methodology: Periods of verification
TC Standard
Summer
limits
Winter
limits
Summer
definition
Summer
analyzed
Extended
period
ISO 7730 24.5 ± 1.5 22.0 ± 2.0 (Non heating) 4Jun - 11Nov 15Apr - 30Nov
EN 15251 0.33 Trm +18.8 ±3 22.0 ± 2.0 (N.D.) 1Jul - 30Sep 15Apr - 30Nov
CIBSE TM52 0.33 Trm +18.8 +3 (N.D.) 1 May - 30 Sep. 1May - 30Sep -
PH overheat 25.0 (air T.) 25.0 (air T.) (N.D.) - Full year
Periods of verification for summer TC conditions and OH detection:
Summary of TC standard limits according to indoor O.T.:
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9. Overheating Assessment of a Passive House Case Study in Spain
36th AIVC Conference. Effective ventilation in high performance buildings.
4. Overheating detection models and methodology: Occupancy verification
Building occupancy timetables for summer and work week, averaged results:
9
TC Standard
Summer
limits
Winter
limits
Summer
definition
Summer
analyzed
Extended
period
ISO 7730 24.5 ± 1.5 22.0 ± 2.0 (Non heating) 4Jun - 11Nov 15Apr - 30Nov
EN 15251 0.33 Trm +18.8 ±3 22.0 ± 2.0 (N.D.) 1Jul - 30Sep 15Apr - 30Nov
CIBSE TM52 0.33 Trm +18.8 +3 (N.D.) 1 May - 30 Sep. 1May - 30Sep -
PH overheat 25.0 (air T.) 25.0 (air T.) (N.D.) - Full year
Summary of TC standard limits according to indoor O.T.:

10. Overheating Assessment of a Passive House Case Study in Spain
36th AIVC Conference. Effective ventilation in high performance buildings.
Too cold - (PMV < - 0.7 )
Cat. C- (-0.7 <PMV < - 0.5)
Cat. B- (-0.5 <PMV < - 0.2)
Cat. A (-0.2 <PMV < + 0.2)
Cat. B+ (0.2 <PMV < 0.5)
Cat. C+ (0.5 <PMV < 0.7)
Too hot (PMV > 0.7)
ISO 7730 Categories:
10%
11%
12%
11%
11%
11%
16%
11%
11%
12%
12%
12%
12%
12%
12%
12%
7%
8%
8%
9%
8%
9%
10%
8%
49%
51%
51%
50%
50%
48%
51%
50%
9%
9%
9%
9%
9%
9%
7%
10%
11%
8%
7%
8%
8%
8%
4%
8%
3%
1%
1%
1%
2%
3%
0%
2%
Day-T.zone
Servicesz.
Night-T.zone
North
South
West
East
Full House
7%
9%
9%
9%
9%
8%
12%
8%
8%
11%
17%
15%
9%
9%
14%
9%
24%
25%
20%
21%
25%
25%
25%
25%
45%
42%
41%
42%
43%
42%
40%
43%
7%
7%
7%
7%
7%
7%
5%
7%
7%
6%
5%
6%
6%
6%
3%
6%
2%
1%
1%
1%
2%
2%
0%
1%
Day-T.zone
Servicesz.
Night-T.zone
North
South
West
East
Full House
5. Results: ISO 7730:2005
10
TC ISO 7730 categories in non-heating period (4 June- 11 November), occupied hours:
TC ISO 7730 categories in full period (15 April - 14 November), occupied hours:
non-heating period:
10 % too hot
full period:
7 % too hot
GOODHOTCOLD

11. Overheating Assessment of a Passive House Case Study in Spain
36th AIVC Conference. Effective ventilation in high performance buildings.
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18
19
20
21
22
23
24
25
26
27
28
29
30
3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
IndoorOperativeTemperature[°C]
Outdoor Running Mean Temperature [°C]
Category I (optimal, PMV < ±0,2) Category II (acceptable, PMV < ±0,5) Category III (discomfort, PMV < ±0,7)
Spring, heated Fall, heated Summer, free-running
Unoccupied hours
5. Results: EN 15251:2007
11
0,2 % too hot
both periods
TC EN 15251 categories:

12. Overheating Assessment of a Passive House Case Study in Spain
36th AIVC Conference. Effective ventilation in high performance buildings.
5. Results: CIBSE TM52:2013
• First criterion:
– Hours that exceed at least 1K over the EN15251 category limits, in a rounded value.
– In our building, the higher temperatures only exceeded 0.4 K over the limit,
thus it can’t be considered as exceedance.
• Second and third criteria are approved.
12

13. Overheating Assessment of a Passive House Case Study in Spain
36th AIVC Conference. Effective ventilation in high performance buildings.
5. Results: PASSIVHAUS
• Criterion: less than 10 % of the hours over 25ºC during the year.
– The weighted house temperature was over 25 ºC during 1034 hours.
– It represents the 11,8 % of the hours of a typical year of 8760 hours.
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14. Overheating Assessment of a Passive House Case Study in Spain
36th AIVC Conference. Effective ventilation in high performance buildings.
6. Conclusions
• This Passive house cannot be considered as overheated.
– According to the results obtained in the latest regulation for OH prevention:
CIBSE TM52 and EN15251.
– With the 11.8 % of the time over 25 ºC, it does not meet the Passivhaus limitation.
– It does not comply with the current Spanish regulation, the frequent high and low temperature exceeds ISO 7730 limits.
• Every standard has proven to be useful or complementary in OH risk detection.
– The Spanish regulation methodology, based on the limits of ISO 7730:2005,
can easily detect which zones of the building have higher risk of high temperatures.
– The EN 15251:2007 reflects more realistically the user perception, since looking into the days where they used additional
natural ventilation they were close to the category III limit.
– The CIBSE TM52 has proven a good step forward in OH risk detection, but it is still poorly defined in different building
areas and limits rounding.
– Passivhaus OH prevention was conceived many years ago for cold central European climate, and after many years only a
few variations have been introduced for warm climates.
– The IE limits have to be improved according to the outdoor environment influence, as happens with the EN 15251.
• Many other problems have been detected in local discomfort conditions.
– The discomfort conditions vary from each orientations and according to their activity levels.
– This has to be considered in future detached house design.
• Recommendations for future:
– OH risk need to be verified separately: Not only to a weighted house temperature but to two or more zones,
depending on the size, shape, orientations and room use.
– Shading elements need to be improved for the transitional months: They were designed to protect from summer
sunpath, forgetting the transitional months. In conjunction with the thermal mass of the building after summer, it
could generate unexpected overheating in the end of summer.
– Verify the impact of the occupancy and the periods of verification: Further research is necessary in future case studies,
considering the findings of the present study.
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15. Overheating Assessment of a Passive House Case Study in Spain
36th AIVC Conference. Effective ventilation in high performance buildings.
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Thanks for your attention
Juanmaria.hidalgo@ehu.eus
linkedin.com/juanmariahidalgo
Juan María Hidalgo Betanzos
ENEDI Research Group. University of the Basque Country UPV/EHU
Laboratory for the Quality Control in Buildings, Basque Government
This work has been funded by the Researcher Training Program
of DEUI of the Basque Government (Spain), as a PhD fellowship.