european mythology and hellenic reality about zero energy
TRANSCRIPT
F. Flourentzou European Mythology and Hellenic Reality about Zero Energy Buildings
0 ASHRAE Greek Chapter, Energy and Buildings Nov. 2013
EUROPEAN MYTHOLOGY AND HELLENIC REALITY
ABOUT ZERO ENERGY BUILDINGS
Flourentzos Flourentzou
Nov 2013
Flourentzos Flourentzou
Estia SA
Par Scientifique EPFL
1015 Lausanne, Switzerland
F. Flourentzou European Mythology and Hellenic Reality about Zero Energy Buildings
1 ASHRAE Greek Chapter, Energy and Buildings Nov. 2013
Energy conservation in Europe is thougnt to conserve heat.
The symbol of a building is a single family house.
We can read contemporary mythology in the symbols
F. Flourentzou European Mythology and Hellenic Reality about Zero Energy Buildings
2 ASHRAE Greek Chapter, Energy and Buildings Nov. 2013
The little
house in
the prairie
is a zero
energy
building
F. Flourentzou European Mythology and Hellenic Reality about Zero Energy Buildings
3 ASHRAE Greek Chapter, Energy and Buildings Nov. 2013
• A passive building in cold Europe:
30 cm of thermal insulation, triple glazing low-e, no thermal bridges
High airtightness (0.5 h-1 at 50 Pa) and ventilation heat recovery unit 80%.
Solar collectors for hot water
A heat pump or wood boiler for heat production
A passive building consumes < 50 kWh/m2 of primary energy for
heating, cooling, ventilation, hot water.
A zero-energy building is a passive building heated by renewable
energy.
F. Flourentzou European Mythology and Hellenic Reality about Zero Energy Buildings
4 ASHRAE Greek Chapter, Energy and Buildings Nov. 2013
• 3 examples of Minergie Buildings
C: Villa mitoyenne à Illkirch - France (2009)
New twin villas Minergie-P
•Minergie GE-005-P
•Minergie VD-626
B: Maison Villageoise à Corcelles (2011)
Minergie refurbishment
A: Ecoquartier Les Fontenettes, Carouge (2012-2016)
7 multi-storey buildings GF+8 Minergie and Minergie-P
335 appartments, 30’000 m2 for social housing
•Minergie F-67-001-P
F. Flourentzou European Mythology and Hellenic Reality about Zero Energy Buildings
5 ASHRAE Greek Chapter, Energy and Buildings Nov. 2013
• 3 examples of Minergie Buildings
•Minergie GE-005-P
•Minergie VD-626
•Minergie F-67-001-P
29 kWh/m2a 22 cm District heating Sewage heat recovery COP 4.5
56 kWh/m2a 8/16 cm 5.5 m2 DCV 12 m3/y
25 kWh/m2a 38 +5 cm 7 m2 80% HR COP 3.5
A
B
C
F. Flourentzou European Mythology and Hellenic Reality about Zero Energy Buildings
6 ASHRAE Greek Chapter, Energy and Buildings Nov. 2013
• From Minergie to a zero energy building
•Minergie GE-005-P
•Minergie VD-626
•Minergie F-67-001-P
29 kWh/m2a
47 kWh/m2a
25 kWh/m2a
140m2
48 m2
25 m2
+
+
+
= 20 kWh/m2a
= 0 kWh/m2a
= 0 kWh/m2a
A
B
C
F. Flourentzou European Mythology and Hellenic Reality about Zero Energy Buildings
7 ASHRAE Greek Chapter, Energy and Buildings Nov. 2013
• From mythology to reality about zero energy buildings
Should we construct small buildings in order to have enough available surface
for solar collectors ?
In order to have energy produced in the building perimeter, should we promote
photovoltaic systems on façades with 30% losses instead of remote renewable
energy?
Why 0 and not -13, -25 or +12?
Zero energy building cannot be an extrapolation of a zero energy
single family house
The building of the second half of hydrocarbon age should go
beyong symbols and green communication
F. Flourentzou European Mythology and Hellenic Reality about Zero Energy Buildings
8 ASHRAE Greek Chapter, Energy and Buildings Nov. 2013
• Cold and hot climate European reality concerning energy demand
Bern Lefkosia
192 (43)
192 (15)
Bern Lefkosia
In the first half of the « hydrocarbon age », European and Greek
engineers and market have more or less the same problem to solve.
F. Flourentzou European Mythology and Hellenic Reality about Zero Energy Buildings
9 ASHRAE Greek Chapter, Energy and Buildings Nov. 2013
• Energy demand after insulating and shading correctly a buillding
After the first step towards low energy buildings, European and
Greek market and engineers have a different problem to solve.
38 (4)
29 (7)
Athina
22 (20)
Bern
30 (28)
Oslo Lefkosia
F. Flourentzou European Mythology and Hellenic Reality about Zero Energy Buildings
10 ASHRAE Greek Chapter, Energy and Buildings Nov. 2013
• technical characteristics of a passive office building
Cold climates Mild climates
Thermal insulation position Sandwich light wall Sandwich light wall
Wall/roof thermal insulation thickness 30 cm 10 cm
Glazing g value 0.6 0.4
Window U value 0.8 W/m2K 1.7 W/m
2K
Ventilation opening dimensions 1X1.8 1X1.8
Number of occupants 35 35
Ventilation airflow (30 m3/pers) 1050/120 m3/h 1050/120 m
3/h
Internal gains (7 W/m2) 3400W 3400W
Lighting power (15.9 W/m2) 7223W 7223W
Solar protection g value 0.15 0.15
F. Flourentzou European Mythology and Hellenic Reality about Zero Energy Buildings
11 ASHRAE Greek Chapter, Energy and Buildings Nov. 2013
• What ventilation system to reduce energy demand?
European mythology: air-tightness, ventilation control, heat recovery
29 (7)
Athina
30 (28)
Oslo
F. Flourentzou European Mythology and Hellenic Reality about Zero Energy Buildings
12 ASHRAE Greek Chapter, Energy and Buildings Nov. 2013
Lefkosia Climate Bern climate
Sum
mer
Win
ter
• DIAL+ dynamic simulation of temperature difference
In Bern there is a high winter recovery potential during day and night
In Lefkosia there is a small recovery potential especially during day
F. Flourentzou European Mythology and Hellenic Reality about Zero Energy Buildings
13 ASHRAE Greek Chapter, Energy and Buildings Nov. 2013
• Heat and cooling demand reduction by ventilation heat recovery
Heat recovery recudes by 45-47% energy demand in cold climates!
Heat recovery recudes by 10-14% energy demand in mild climates!
F. Flourentzou European Mythology and Hellenic Reality about Zero Energy Buildings
14 ASHRAE Greek Chapter, Energy and Buildings Nov. 2013
• Heat and cooling demand and primary energy consumption
Heat recovery is more effective with polluting energies
Energy demand
Primary energy consumption
F. Flourentzou European Mythology and Hellenic Reality about Zero Energy Buildings
15 ASHRAE Greek Chapter, Energy and Buildings Nov. 2013
• Heat recovery: Environmental emissions and embodied energy
Heat recovery: 1.5 kWh/m2y, Simple ventilation: 0.64 kWh/m2y
Life span 25 years
F. Flourentzou European Mythology and Hellenic Reality about Zero Energy Buildings
16 ASHRAE Greek Chapter, Energy and Buildings Nov. 2013
• Heat recovery: Primary energy cost for fans (X 2.9) and grey energy
Embodied energy is low but not negligible, fan energy is high
for
2 D
C f
an
s
for
gre
y e
ne
rgy
7 k
Wh
/m2y
1.5
kW
h/m
2y
F. Flourentzou European Mythology and Hellenic Reality about Zero Energy Buildings
17 ASHRAE Greek Chapter, Energy and Buildings Nov. 2013
• Primary energy cost and savings
Heat recovery is a simple question in Sweden, Greece and Cyprus
Fans & embodied primary energy cost
Primary energy savings
Heat recovery is a complex question in Switzerland
F. Flourentzou European Mythology and Hellenic Reality about Zero Energy Buildings
18 ASHRAE Greek Chapter, Energy and Buildings Nov. 2013
• From mythology to reality in Europe
Spectacular reduction of envelope heat losses
Before refurbishment After refurbishment
F. Flourentzou European Mythology and Hellenic Reality about Zero Energy Buildings
19 ASHRAE Greek Chapter, Energy and Buildings Nov. 2013
• Before and after reburbishment
Spectacular but?
F. Flourentzou European Mythology and Hellenic Reality about Zero Energy Buildings
20 ASHRAE Greek Chapter, Energy and Buildings Nov. 2013
• Window use
Almost 1/3 of the windows are open after refurbishment with Text -
4°C
F. Flourentzou European Mythology and Hellenic Reality about Zero Energy Buildings
21 ASHRAE Greek Chapter, Energy and Buildings Nov. 2013
And more windows
F. Flourentzou European Mythology and Hellenic Reality about Zero Energy Buildings
22 ASHRAE Greek Chapter, Energy and Buildings Nov. 2013
• A multistorey building is not an extrapolation of a single family house
According to code calculations, user behaviour is evacuated
Designers should take it into accound like real consumption does
F. Flourentzou European Mythology and Hellenic Reality about Zero Energy Buildings
23 ASHRAE Greek Chapter, Energy and Buildings Nov. 2013
• « mythological » and real user behaviour
Real consumption for lighting is higher, real solar gains in winter are
50-70% lower than calculated ones according to regulations standard
use, in summer 30-50% of glazed area is not shaded
Standard use
Blinds down in summer
Blinds up in winter
Blinds down when blinding
Real Use
50-70% shading summer
or winter indifferently
88-90% of users do not
use the blinds
1.3 to 2 average blind
movements per week
F. Flourentzou European Mythology and Hellenic Reality about Zero Energy Buildings
24 ASHRAE Greek Chapter, Energy and Buildings Nov. 2013
• Hellenic reality about ventilation
Fans & embodied primary energy cost
Primary energy savings
Heat recovery net saving potential (primary energy) is low and
sometimes negative in mild climates
F. Flourentzou European Mythology and Hellenic Reality about Zero Energy Buildings
25 ASHRAE Greek Chapter, Energy and Buildings Nov. 2013
• Heat and cooling demand reduction by night cooling
Night ventilative cooling in almost zero energy buildings in cold mild
climates is necessary, in mild climates essential!
F. Flourentzou European Mythology and Hellenic Reality about Zero Energy Buildings
26 ASHRAE Greek Chapter, Energy and Buildings Nov. 2013
• Ideal ventilation strategies for Hellenic zero energy buildings
In winter, ventilation provides air quality: 30 m3/h per person during hours of
use, minimum ventilation of 0.2 m3/m2h outside hours of use to save energy
In summer, ventilation provides air quality: 30 m3/h per person during hours of
use.
In summer, ventilation provides night cooling: 2-4 air changes when Text<Tint
In summer, when outside temperature is fresh ( <28°C), wind breeze is
cooling the user but when temperature rises ( > 26°C), wind breeze is heating
the building => cross ventilation should be reduced to provide only air quality.
F. Flourentzou European Mythology and Hellenic Reality about Zero Energy Buildings
27 ASHRAE Greek Chapter, Energy and Buildings Nov. 2013
• Possible strategies: Closed or open?
Install mechanical ventilation with low airflow (and heat recovery) for winter and
high airflow for summer night time ventilation
Or
Design natural ventilation able to be manually controlled, taking into account
user natural behaviour
Or
Design automatically controlled natural ventilation
F. Flourentzou European Mythology and Hellenic Reality about Zero Energy Buildings
28 ASHRAE Greek Chapter, Energy and Buildings Nov. 2013
• Night cooling ventilation strategy for Lefkosia new Townhall
Guarantee safety and provide large oppening possibilities.
F. Flourentzou European Mythology and Hellenic Reality about Zero Energy Buildings
29 ASHRAE Greek Chapter, Energy and Buildings Nov. 2013
• natural ventilation design: user possibilities
A window offers 30 to 366 m3/h stack effect
airflow at ΔΤ 5°C
F. Flourentzou European Mythology and Hellenic Reality about Zero Energy Buildings
30 ASHRAE Greek Chapter, Energy and Buildings Nov. 2013
• Use of ceiling fans to keep windows closed and rise set temperature
15 % rise of cooling energy per 1 °C of set température decrease
Ceiling fans may save 30% of cooling energy consumption
0
20
40
60
80
100
23-24°C 21-26°C 21-28°C
KW
h/m
2
F. Flourentzou European Mythology and Hellenic Reality about Zero Energy Buildings
31 ASHRAE Greek Chapter, Energy and Buildings Nov. 2013
• Heating and cooling system
What energy system for Hellenic passive buildings?
38 (4)
Pa
ss
ive
Bu
ild
ing
29 (7)
Athina
22 (20)
Bern
30 (28)
Oslo Lefkosia
192 (43)
Sta
nd
ard
Bu
ild
ing
192 (15)
Bern Lefkosia
F. Flourentzou European Mythology and Hellenic Reality about Zero Energy Buildings
32 ASHRAE Greek Chapter, Energy and Buildings Nov. 2013
• Need of correct cooling load dimensionning
350 W/m2 of total cooling initially proposed
Static dimensionning 24-42°C is not adapted for low energy
buildings
10 W/m2 of simulated heating load according to ISO 15265
50 W/m2 of simulated sensible cooling load according to ISO 15255
F. Flourentzou European Mythology and Hellenic Reality about Zero Energy Buildings
33 ASHRAE Greek Chapter, Energy and Buildings Nov. 2013
• Technical installation sobriety
Lefkosia townhall passive building technical installations
Installation of a High COP VRV, 135 W/m2
F. Flourentzou European Mythology and Hellenic Reality about Zero Energy Buildings
34 ASHRAE Greek Chapter, Energy and Buildings Nov. 2013
• COP according to demand
Oversising of heat pumps costs investment money but also energy
✖ ✓
We have to reinvent the job of the mechanical engineer
F. Flourentzou European Mythology and Hellenic Reality about Zero Energy Buildings
35 ASHRAE Greek Chapter, Energy and Buildings Nov. 2013
• Heating and cooling emmition
Current machines are not adapted to distribute low intensity energy
220 fan electric Watts to distribute 2500 thermal Watts is to match
✖ ✓
F. Flourentzou European Mythology and Hellenic Reality about Zero Energy Buildings
36 ASHRAE Greek Chapter, Energy and Buildings Nov. 2013
• European mythology and Hellenic reality about zero energy buildings
Hellenic zero energy energy engineers should invent their own mythology
The objective is the same: energy needs < 40 kWh/m2y for heating and cooling
and extensive use of renewable energy
A zero energy building is a completely different reality of the reality we know
We have to be open to revisit our rules of thumb
The good technical solutions of the Hellenic zero energy have to be invented,
they do not exist to be imported