Technical Installations in Passive Houses Part 1: Ventilation Systems
Transcript of Technical Installations in Passive Houses Part 1: Ventilation Systems
Ventilation Systems / 1 © Prof. Dr. Harald Krause
Technical Installations in Passive Houses
Part 1: Ventilation Systems
Prof. Dr. Harald Krause
www.btec-rosenheim.de www.fh-rosenheim.de
Århus 2007-08-29
Ventilation Systems / 2 © Prof. Dr. Harald Krause
Ventilation in Passive Houses
1. Indoor Air Quality and Ventilation
2. Cross Flow Ventilation in Dwellings
3. Components of a Ventilation System
4. Design of Ventilation Systems in Dwellings
5. Energy Saving with Heat Recovery
Ventilation Systems / 3 © Prof. Dr. Harald Krause
Indoor Air Quality and Ventilation Main Functions
Main Function: High Indoor Air Qualitypollutant concentrations
air humidity
Further Functions: Air ProcessingCleaning - Filtering
Heating (Cooling)
Dehumidification of indoor air
Energy Saving with Heat Recovery Systems
Ventilation Systems / 4 © Prof. Dr. Harald Krause
Indoor Air Quality and Ventilation Pollutants
Main Pollutants:
CO2
water vapour - humidity
odours
toxic gases
microorganisms
radioactive materials
Function of Ventilation Systems in Dwellings:
Keep concentration of pollutants and humidity as low as necessary
Extract odours
How to do this: supply fresh air, extract „polluted“ air
Ventilation Systems / 5 © Prof. Dr. Harald Krause
Indoor Air Quality and Ventilation Air Change Rate
Air Change Rate
Ve : air flow rate in m³/h
n: air change rate in h-1
Vroom: volume of the dwelling or room in m³
room
e
V
Vn
&=
Ventilation Systems / 6 © Prof. Dr. Harald Krause
Indoor Air Quality and Ventilation Max von Pettenkofer
Max von Pettenkofer (1858)
Use CO2 concentration as a benchmark for air quality
Ventilation Systems / 8 © Prof. Dr. Harald Krause
Indoor Air Quality and VentilationCO2-Concentration
CO2-concentration in indoor air
0,07 Vol.-%: recommended for occupied space
0,1 Vol.-%: Pettenkofer
0,15 Vol.-%: [DIN 1946-2]
0,5 Vol.-%: industrial-rooms
4,0 Vol.-%: exhale air
Caution: above 2,5 Vol.-% CO2 health risk
Ventilation Systems / 9 © Prof. Dr. Harald Krause
Indoor Air Quality and VentilationAir Flow Rate and CO2
0,06 0,08 0,10 0,12 0,14 [Vol%]
10
20
30
40
50
60
70
80
[m³/h]
100
air
flo
wra
te p
er p
erso
n
max. indoor CO2-concentration
CO2-emission per hour and person
sleeping (12 l/h)average (18 l/h)working (23 l/h)
Ventilation Systems / 10 © Prof. Dr. Harald Krause
Cross Flow Ventilation
Three Ventilation Zones
Supply “fresh” air to living, bed-, working rooms
Extract polluted, humid air from kitchen, WC etc.
supply air
• living
• sleeping
• children
• working
exhaust air
• kitchen
• bath
• WC
• utility
overflow
corridor
Ventilation Systems / 11 © Prof. Dr. Harald Krause
Cross Flow Ventilation Example
Example:
Zoning
exhaust air
supply air
overflow
Ventilation Systems / 12 © Prof. Dr. Harald Krause
air change rate 0,4 h-1, approx. 85 m² floor area
living25 m²
40 m³/h
bedroom16 m²
30 m³/h
children15 m²
20 m³/h
Supply Air
bath10 m²
30 m³/h
kitchen12 m²
60 m³/h
Exhaust Air
corr.8 m²
0,64 h-11,2 h-1
2 h-1
0,75 h-1
0,53 h-1
Cross Flow Ventilation Example
Ventilation Systems / 14 © Prof. Dr. Harald Krause
Components of a Ventilation System Overview
Balanced passivehouse ventilation:central ventilation unitseparated ducts for supply and exhaust airheat recoveryfiltering of outside airflow off vents
components:1. ventilation unit2. supply air outlet valve3. exhaust air inlet valve4. flow off vents5. air ducts6. outgoing air outlet7. outside air inlet
1
2 3
4
5
6
7
Ventilation Systems / 15 © Prof. Dr. Harald Krause
Filter
House
Air Ducts, e.g. ∅ 200mm
Condensate Outlet Device
Components of a Ventilation System Subsoil Heat Exchanger with Air
Ventilation Systems / 16 © Prof. Dr. Harald Krause
House
PE Ducts (water and frost protection liquid)
Outside Air
Water-to-Air Heat Exchanger
Components of a Ventilation System Subsoil Heat Exchanger with Water
Ventilation Systems / 17 © Prof. Dr. Harald Krause
Components of a Ventilation System Subsoil Heat Exchanger with Water or Air
Ventilation Systems / 18 © Prof. Dr. Harald Krause
Efficiency of heat recovery
85%
DC-motors
Air bypass for summer
Preheating of outside air for
frost protection
Balance of supply and exhaust
air flow rates
Components of a Ventilation System Central Unit - Example
Ventilation Systems / 19 © Prof. Dr. Harald Krause
Components :
Coarse filter G3 (1), fine filter F7 (2)
DC-fans (3)
Electrical preheating (4)
Bypass (5)
Heat recovery unit, counterflow heat
exchanger (6)
Condensate outlet (7)
Components of a Ventilation System Central Unit - Example
Ventilation Systems / 20 © Prof. Dr. Harald Krause
Components of a Ventilation System Air-to-Air Heat Exchanger – Heat Recovery
Efficiency of Heat Recovery:
Tzl: supply air temperature
Tal: outside air temperature
Ti: exhaust air temperatur (indoor air)
Example:
Tzl: 15 °C, Tal: 0 °C, Ti: 20°C
Φ = 75 %
Cross-Counter Flow
Cross Flow
ali
alzl
TT
TToder
−−
=Φη
Ventilation Systems / 23 © Prof. Dr. Harald Krause
Components of a Ventilation System Central Unit - Electrical Efficiency
Air Flow Rate in m³/h
elec
tric
alef
ficie
ncy
in W
h/m
³
External Pressure
Ventilation Systems / 24 © Prof. Dr. Harald Krause
Components of a Ventilation System Piping Systems
Material for Air Ducts
Zinc coated steel plate
Stainless steel, aluminium
Plastics (check, whether suitable for air, no emissions)
Types of Air Ducts
Round, folded spiral-seam tube (cheap, low air resitance)
Oval, folded spiral-seam tube (e.g. over suspended ceiling)
Plastics, (round, oval)
Flexible tubes (high air resistance, cleaning?)
Custom made
We recommend round folded spiral-seam tubes !
Ventilation Systems / 25 © Prof. Dr. Harald Krause
Components of a Ventilation System Piping Systems: Foulded Spiral-Seam Tubes
Sealing
Ventilation Systems / 26 © Prof. Dr. Harald Krause
Components of a Ventilation System Piping Systems: Oval Foulded Spiral-Seam Tubes
Ventilation Systems / 27 © Prof. Dr. Harald Krause
Components of a Ventilation System Thermal Insulation of Air Tubes
ref.: Drexel&Weiss
Ventilation Systems / 28 © Prof. Dr. Harald Krause
Components of a Ventilation System Exhaust Air Inlet Valve
Ventilation Systems / 29 © Prof. Dr. Harald Krause
Components of a Ventilation System Supply Air Outlet Valve
Wall Outlet
ref.: Drexel&Weiss
Blower Nozzle
Ventilation Systems / 30 © Prof. Dr. Harald Krause
Floor Outlet Floor Outlet
Ceiling Outlet
ref.: Drexel&Weiss
Components of a Ventilation System Supply Air Outlet Valve
Ventilation Systems / 31 © Prof. Dr. Harald Krause
Components of a Ventilation System Exhaust Air Outlet
Ventilation Systems / 32 © Prof. Dr. Harald Krause
Components of a Ventilation System Filters
Ventilation Systems / 33 © Prof. Dr. Harald Krause
ref.: Drexel&Weiss, Rehau
Components of a Ventilation SystemOutside Air Inlets
Ventilation Systems / 34 © Prof. Dr. Harald Krause
Components of a Ventilation SystemCondensate Outlet Devices for Subsoil Heat Exchangers
Condesate outlet device, if installed in basement
Ventilation Systems / 35 © Prof. Dr. Harald Krause
Components of a Ventilation SystemCondensate Outlet Devices for Subsoil Heat Exchangers
Pump shaft, if there is no basement
Ventilation Systems / 36 © Prof. Dr. Harald Krause
Components of a Ventilation SystemSubsoil Heat Exchanger with Water
Ventilation Systems / 37 © Prof. Dr. Harald Krause
Design of Ventilation Systems in Dwellings
Zoning: Supply, exhaust and overflow zones
Calculation of air flow rates
Take maximum of both air flow rates as design air flow rate
Divide up the air flow into the rooms of the supply air zone
Use the designed extract air flow rates for the rooms in theexhaust air zone
60 m³/h40 m³/h20 m³/h
Exhaust air flow rates:KitchenBath, utility etc.WC
30 m³/hSupply air flow rate per person
Ventilation Systems / 38 © Prof. Dr. Harald Krause
Basic rules:
Keep pressure loss as low as possible
Keep length of tubes as short as possible
Round tubes preferred
Dimensioning of ducts, in- and outlets
Chose a appropriate ducting system (round tubes preferred)
Positioning of in- and outles
Design sound absorbers (noise from central unit, air flow, between rooms)
Heat insulation of tubes
Positioning of outside air inlet (not polluted, driving rain protected, approx. 1,5 m above ground)
Dimensioning of subsoil heat exchanger (if needed)
Design of Ventilation Systems in Dwellings
Ventilation Systems / 39 © Prof. Dr. Harald Krause
Design of Ventilation Systems in Dwellings
ref.: Drexel&Weiss
Ventilation Systems / 40 © Prof. Dr. Harald Krause
Design of Ventilation Systems in DwellingsSubsoil Heat Exchangers with Air and Water
ref.: Drexel&Weiss
0.6 m per m³/h0.3 to 0.45 m per m³/hTube length
in combination withcompact heat pump unit
Frost Protection onlyAir Flow
Design guidlines: with Air
Design guidlines: with Water
Ventilation Systems / 41 © Prof. Dr. Harald Krause
Example:
Single family house with 4 inhabitants
1 kitchen, 2 bath rooms, 1 WC
150 m² floor area
Supply air: 4 x 30 m³/h = 120 m³/h
Extract air: 60 + 2 x 40 + 20 = 160 m³/h
Take maximum as design air flow rate: 160 m³/h
reduce this value with 0.77 as standard flow rate
Check mimimum air change rate in relation to hygienic
requirements:
160 m³/h / 150 m² x 2,5 m = 0,43 h-1
mimimum of 0,3 h-1 is complied
Design of Ventilation Systems in Dwellings
Ventilation Systems / 42 © Prof. Dr. Harald Krause
Energy Saving with Heat Recovery
EN 832: Influence of heat recovery on the annual heat demand
Calculation of the effective air exchange rate nL
nL = nsystem ⋅ ( 1 - ΦHR) + nL,inf
nsystem: average air change rate achieved through ventilation system
ΦHR: total heat recovery efficiency including subsoil heat exchanger
nL,Rest: infiltration air exchange rate caused by residual leakage throughthe airtight envelope
0,080,030,6
0,190,081,5
0,380,153
nL,Rest for heatingload in h-1
nL,inft for annualheat demand in h-1
n50-Wert
in h-1example: effective air exchangerates for a typ. single familyhouse, assuming average wind screening according to PHPP 2007
Ventilation Systems / 43 © Prof. Dr. Harald Krause
Energy Saving with Heat Recovery
Unit outside or inside
of the heat exchanging envelope
Keep outside air tubes in a warm room or supply airtubes in a cold room as short as possible !
Ventilation Systems / 44 © Prof. Dr. Harald Krause
Ventilation heat losses
Solar heat gains
Heat demand
Transmission heatlosses
Internal heat gains
Energy Saving with Heat RecoveryEnergy Balance
Ventilation Systems / 45 © Prof. Dr. Harald Krause
Energy Saving with Heat RecoveryEnergy Balance: Example for a Single Familiy House
15
9,7
21,3
40,6
22,215,9
1,0
0
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30
40
50
60
70
Heat Gains Heat Losses
kW
h/m
²
Saving through subsoil HE
Saving through HR
Ventilation losses
Transmission losses
Solar heat gains
Internal heat gains
Annual heat demand
Ventilation Systems / 46 © Prof. Dr. Harald Krause
Example
Ventilation Systems / 47 © Prof. Dr. Harald Krause
Example
Ventilation Systems / 48 © Prof. Dr. Harald Krause
Example