RADON PREVENTIVE MEASURES FOR NEW BUILDINGS

Transcription

1 RADON PREVENTIVE MEASURES FOR NEW BUILDINGS training material International Atomic Energy Agency

2 Prepared by: Martin Jiránek CZECH TECHNICAL UNIVERSITY Faculty of Civil Engineering, Praha Reviewed by: Chris Scivyer, BRE, UK Bernard Collignan, CSTB, France Olli Holmgren, STUK, Finland Aleksandar Birovljev, Eurofins Radonlab, Norway

3 CONTENT 1. Purpose of prevention 2. Factors influencing the design 3. Principles of preventive measures 4. General recommendations 5. Ensuring air-tightness of the substructure 6. Sub-slab depressurization 7. Air gap depressurization 8. Measures for houses on crawl spaces 9. Ventilation systems

4 1. PURPOSE OF PREVENTION The purpose of radon preventive measures is to secure that radon concentration in every room of the habitable space is lower than the reference level or design value. Reference level is prescribed by legislation within the range Bq/m 3. Design value is prescribed by future owner (below reference level). Fulfilment of this objective is verified by measurement of radon concentration under the ventilation rate satisfying the minimum hygiene requirements.

5 2. FACTORS INFLUENCING THE DESIGN Radon potential of a building site Position of the house in the soil Location of habitable rooms Underfloor heating PREVENTIVE MEASURES Type and depth of foundations Workmanship, experience of the contractor Sub-floor layers of high permeability Method of ventilation Technical standards, building codes

6 2.1 Radon potential of a building site Availability of radon in the soil - radon concentration in the soil air Ability of radon to migrate in the soil - soil permeability Usual categories: low, medium, high Classification can be performed for: particular building site urban area, planning area municipal area Classification can be based on: geological data indoor radon data

7 2.1 Radon potential of a building site Example from CZ - classification into risk areas based on geological data Soil gas radon concentration and soil permeability are measured directly on a building site. Radon risk category is determined according to the following table. Radon risk Soil gas radon concentration (kbq/m 3 ) high vysoké High vysoký risk riziko index Medium střední riziko index risk Low/Medium přechodná oblast risk Low nízké nízký riziko index risk medium low Soil permeability low medium high

8 2.1 Radon potential of a building site Example - classification into risk areas based on indoor radon data Areas are identified by % of houses with indoor radon concentration above the reference level 200 Bq/m 3, for example: < 1 % low risk area 1 10 % medium risk area > 10 % high risk area

9 2.1 Radon potential of a building site Example from UK - classification into risk areas based on combination of indoor radon data and geological data The mapping database holds risk data by postcode. Indicative maps based upon 1km grid directly show the type of protection none, basic, full.

10 2.2 Position of the house in the soil Underground water House on a ventilated crawl space House on an artificially created fill of low permeability House founded under the water table level Low risk of radon penetration from the soil into a house

11 2.2 Position of the house in the soil Permeable soil Permeable soil Permeable soil House on a ground House on a slope House with a cellar High risk of radon penetration from the soil into a house

12 2.3 Location of habitable rooms On the floors that are in direct contact with the soil On the upper floors without contact with the soil

13 2.4 Type and depth of foundations Gap Reinforcement Crawl space Gaps Reinforced slab Waterstop

14 2.5 Risk factors Underfloor heating Increases pressure difference Flooring Underfloor heating Thermal insulation Blinding concrete Course gravel Sub-floor layers of high permeability Subsoil Radon reservoir

15 2.6 Method of ventilation Ventilation systems: natural, mechanical, hybrid In modern buildings it is not possible to rely on infiltration through airtight windows to satisfy ventilation requirements. Buildings should have a reliable ventilation system. Ventilation system influences ventilation rate and sometimes also radon supply rate and thus indoor radon concentration. Radon concentration C Ventilation rate J n. V Radon supply rate Interior air volume

16 2.7 Technical standards, workmanship Technical standards, building codes Dealing with protection of buildings against radon All other relevant standards Radon preventive measures are part of the building structure. They must be evaluated completely, particularly with regard to building physics, thermal protection of buildings, building waterproofing, etc. Workmanship, skills, experience of the contractor

17 3. PRINCIPLES OF PREVENTIVE MEASURES 3.1 Separating a building from the soil Building on pillars Building on crawl spaces

18 3. PRINCIPLES OF PREVENTIVE MEASURES 3.2 Ensuring air-tightness of the substructure Radon barrier material placed over the entire surfaces of walls and floors in contact with the soil This approach is not effective in existing houses!!!

19 3. PRINCIPLES OF PREVENTIVE MEASURES 3.3 Changing the pressure difference between the soil and the house by soil or air gaps depressurization Fan generating underpressure under the house or within the air gap is installed if natural draught is not sufficient.

20 3. PRINCIPLES OF PREVENTIVE MEASURES 3.4 Diluting indoor concentration by increased ventilation Efficient ventilation systems are: mechanical exhaust air ventilation with outdoor air inlets mechanical supply and exhaust air ventilation with heat recovery

21 3. PRINCIPLES OF PREVENTIVE MEASURES 3.5 Combining radon-proof insulation + subslab depressurization Radon-proof insulation Drainage layer of coarse gravel Roof fan or rotating cowl to improve the draught Vertical exhaust PVC pipe Interconnecting PVC pipe Perforated flexible pipes - Floor layers - Radon-proof membrane - Bonding primer or geotextile - Blinding concrete - Geotextile - Coarse gravel with perforated pipes - Subsoil

22 3. PRINCIPLES OF PREVENTIVE MEASURES The type and the degree of protection depends on the radon risk of the building site and other factors influencing the design. Radon risk Measures Principle of protection Low Tradition design No special protection is required. No open connections from the building to the ground. Medium High Standard (basic) radon protection Radon-protecting design Increased (full) radon protection Radon-proof design The basic measure is an impermeable substructure: reinforced concrete radon-proof insulation Impermeable substructure is usually combined with: sub-slab depressurization air gaps ventilation

23 3.7 Example of the Czech prevention Radon index Low Medium or high Principle of protection Water resistant construction waterproof insulation or waterproof reinforced concrete construction Water resistant construction or radonproof insulation in dependence on the type of a building and type of ventilation

24 3.7 Example of the Czech prevention Houses with naturally ventilated habitable rooms on the floors in direct contact with the soil Protection = radon-proof insulation Combination with soil or air gap ventilation must be applied, if: Soil gas radon concentration exceeds: 60 kbq/m 3 in highly permeable soils, 140 kbq/m 3 in soils with medium permeability, 200 kbq/m 3 in soils with low permeability. Highly permeable gravel layer is placed under the house Floors resting on the soil are equipped with under-floor heating

25 3.7 Example of the Czech prevention Houses with habitable rooms located on the upper floors Protection = water resistant construction water-proof insulation or waterproof reinforced concrete construction Conditions that must be satisfied: a reliable ventilation rate is ensured in any place of the contact floor the ceiling above the contact floor is airtight with sealed services penetrations the entrances to the contact floor from the other floors are ensured with doors of a good air-tightness and equipped with a door closer

26 3.7 Example of the Czech prevention Houses equipped with mechanical ventilation (in all habitable rooms of the contact floor) Protection = water resistant construction water-proof insulation or waterproof reinforced concrete construction Houses on crawl spaces Protection = crawl space ventilation; water-proof or radon-proof courses in the floor above the crawl space applied only under defined conditions

27 3.8 Example of Norwegian prevention Approach based on radon risk evaluation. 4 Low radon risk general preventive measures: Prevention of leakage at critical points radon barriers and / or durable sealants Ground ventilation / depressurisation Balanced ventilation in the building 4 Medium or high radon risk additional, extended measures Radon membranes with thickness > 0.3mm Extended ground ventilation / depressurisation Choice of radon tight construction and building materials

28 3.8 Example of Norwegian prevention A- tough and thick membranes (asphaltpolymer, polypropilene) B-membrane sandwiched between concrete and insulation (plastic PE, Al-bitumen, asphalt) C-above concrete slab membrane (liquid or plastic membranes)

29 3.8 Example of Norwegian prevention Sealing critical points and preventing future cracks

30 3.8 Example of Norwegian prevention Ground ventilation / depressurisation radon well

31 3.8 Example of Norwegian prevention Ground ventilation / depressurisation radon well

32 4. GENERAL RECOMMENDATIONS Surface finishing around the building should be permeable Backfill around the building should be permeable Constructions on which radon-proof insulation will be applied should be in simple shapes Non-ventilated permeable layers under the building should be avoided

33 4. GENERAL RECOMMENDATIONS Construction of installation shafts should have good airtightness, pipe penetrations should be sealed Ceilings above the contact floors should have good airtightness, pipe penetrations should be sealed Boiler or other device consuming indoor air Direct supply of outdoor air for boilers and furnaces in order to minimize underpressure in contact floors

34 4. GENERAL RECOMMENDATIONS Staircase shafts leading from the underground floors should be divided from the staircase shafts leading to higher floors by doors of good airtightness Doors of good airtightness and equipped with a door closer Alternatively the entrance to the underground floors could be from outside

35 5. AIR-TIGHT SUBSTRUCTURE Airtightness is ensured by application of radon proofinsulation (RPI) over the entire surfaces of walls and floors in contact with the soil. RPI fulfils also the function of waterproof insulation it is selected from standard waterproof materials RPI should have verified radon barrier properties Durability of RPI should correspond to the lifetime of the building

36 5.1 Position of RPI in the substructure Above slab application Sub slab application - Floor layers - Protective layer - Radon-proof insulation - Bonding primer or geotextile - Blinding concrete - Leveling layer - Subsoil - Floor layers - Blinding concrete - Protective layer - Radon-proof insulation - Geotextile - Leveling layer - Subsoil

37 5.2 Properties of RPI RPI must withstand predictable deformations and movements of the substrate and foundation construction Tensile strength, elongation, tear resistance and other material and physical parameters must be taken into account when designing radon-proof courses RPI must be resistant to soil corrosion caused primarily by microbiological agents and chemical compounds occurring in the soil RPI must have low radon diffusion coefficient

38 5.3 Testing of barrier properties of RPI Reasons for testing Great amount of tanking materials of different chemical composition Difficult selection of membranes with barrier properties against radon Tested quantity Radon diffusion coefficient is a material property that determines diffusive transport it seems to be a convenient parameter for testing of barrier properties

39 5.4 Summary of radon diffusion coefficient values Measured by the Faculty of Civil Engineering of the Czech Technical University in Prague and National Radiation Protection Institute in Prague

40 5.5 Design of radon-proof insulation Three different approaches are used: 1. Limit for the maximal value of D Applied for example in Ireland (max D = m 2 /s ) 2. Limit for the minimal thickness of the membrane Applied for example in Germany (d 3l) 3. Calculation of the membrane thickness in dependence on the soil and building characteristics Applied for example in Czech Republic, Slovakia, Spain

41 Example from CZ - formula for calculating the thickness of RPI d 5.5 Design of radon-proof insulation l. arcsinh 1. l.. C S.( A f C. n. V d if C s radon concentration in the soil gas (Bq/m 3 )..radon decay constant (0,00756 h -1 ) d..thickness of the membrane (m) l.. radon diffusion length in the membrane l = (D/ ) 1/2 (m) D. radon diffusion coefficient in the membrane (m 2 /h) 1 safety factor A f A w.floor and wall areas in contact with the soil (m 2 ) n ventilation rate (h -1 ) C dif fraction of reference level caused by diffusion (Bq/m 3 ) A w )

42 Thickness of insulation (mm) 5.5 Design of radon-proof insulation Example from CZ - thickness of RPI calculated for different values of D, C s and soil permeability Cs = 200 kbq/m 3 + low permeability or Cs = 60 kbq/m 3 + high permeability 1 0,1 0,01 Cs = 100 kbq/m 3 + low permeability or Cs = 30 kbq/m 3 + high permeability Cs = 30 kbq/m 3 + low permeability or Cs = 10 kbq/m 3 + high permeability 0,001 1,0E-13 1,0E-12 1,0E-11 1,0E-10 1,0E-09 Radon diffusion coefficient D (m 2 /s)

43 5.6 Materials for radon-proof insulation Suitable materials Bitumen membranes based on plastomeric APP or elastomeric SBS bitumen Polymeric flexible membranes made of PVC, PP, LDPE, HDPE, TPO Unsuitable materials Bitumen membranes based on oxidised bitumen All membranes with the reinforcing fabric based on paper boards, rag boards or jute hessian Rubber membranes made of EPDM Cement coatings Bentonite materials

44 5.6 Materials for radon-proof insulation Prohibited materials Bitumen membranes with Al foil barrier properties are formed by AL foil that can be easily damaged, ruptured Plastic membranes with dimples (Delta, Platon, Tefond, etc.) it is almost impossible to create air-tight joints Radon diffusion coefficient (m 2 /s) HDPE dimpled membrane (4,1 0,1) Overlap joint sealed by self adhesive tape (7,4 0,7).10-10

45 5.6 Materials for radon-proof insulation Water-proof materials X Radon-proof materials Water-proof materials are not automatically radonproof Water-proof materials that are permeable for water vapour are also permeable for radon Radon-proof materials are also water-proof

46 5.7 Execution of radon-proof courses RPI should be installed by qualified and experienced personnel Regular supervision of the insulating works should be carried out Prior to the application of RPI, an inspection of the substrate should be carried out RPI, once placed, is to be protected as soon as possible from mechanical damage caused by subsequent construction and finishing works (by covering with a protective geotextile, with plastic panels, with a concrete screed, thermal insulation boards, etc.).

47 5.7 Execution of radon-proof courses All joints and services penetrations must be airtight Joints of self-adhesive membranes should be sealed by torching Radon diffusion coefficient (m 2 /s) SBS modified bitumen membrane Overlap joint sealed by torching Self-adhesive overlap joint (7,1 0,2) (8,6 1,0) , ,

48 5.7 Execution of radon-proof courses Example from UK application of a polymeric membrane By: Chris Scivyer, BRE, UK

49 5.8 Air-tightness of services penetrations Factors influencing the air-tightness Position of the penetration (corners) Applicability of details

50 5.8 Air-tightness of services penetrations Examples of 4mm asphalt-polymer membranes sealed with open flame torching.

51 5.8 Application of viscous liquid membranes Example of a bitumen-polymer viscous liquid membrane

52 5.8 Air-tightness of services penetrations Examples of details without dilatation movements Bitumen membranes Polymeric membranes

53 5.9 Thermal protection X radon protection Radon-proof insulation must prevent radon from penetrating through an air gap between perimeter thermal insulation and foundations Elimination of thermal bridges should not result in radon bridges Thermal insulation Internal plaster Head joint free of mortar Perimeter air gap Hollow clay blocks Thermal insulation XPS 80 mm Perimeter air air gap gap Hollow clay blocks Damp-proof membrane (DPM) Section A - A Internal plaster Head joint free of mortar Perimeter air gap Hollow clay blocks Thermal insulation XPS 80 mm

54 5.9 Eliminating radon bridges Interrupting an air gap between perimeter thermal insulation and foundations Hollow clay blocks HDPE corner strip Radonproof membrane Protective fabric Bitumen radonproof membrane Bit. bonding primer Continuous HDPE membrane with airtight joints

55 5.9 Example of eliminating radon bridges in UK Interrupting an air gap in cavity walls (slab on grade) By: Chris Scivyer, BRE, UK

56 5.9 Example of eliminating radon bridges in UK Interrupting an air gap in cavity walls (crawl space) By: Chris Scivyer, BRE, UK

57 5.9 Example of eliminating radon bridges in CZ Single family house ROOM Bq/m 3 BOILER ROOM ROOM Bq/m 3 HALL BATHROOM LIVING ROOM WC Bq/m 3 Average indoor Rn conc. before mitigation: Bq/m 3 KITCHEN BEDROOM Bq/m 3 Soil gas Rn concentration: 5,3 137,6 kbq/m 3 Third quartile: 50,4 kbq/m 3

58 5.9 Example of eliminating radon bridges in CZ Factors responsible for failures Radon transport through the radon bridge in the external walls Radon penetration through joints in the radon-proof insulation and around pipe penetrations

59 5.9 Example of eliminating radon bridges in CZ Eliminating the bridge Removed part of XPS boards Bitumen coating 3 mm Existing waterproofing PVC Ø 60 mm PVC Ø mm Gravel layer Borehole Ø 80 mm Drilled perforated pipe Ø 60 mm PU foam

60 5.9 Example of eliminating radon bridges in CZ Trench excavated in the ground PVC 100 mm Fan NPV 190/125 installed 1 m above the terrain PVC 125 mm under the terrain Drilled pipe 60 mm D = 6,0 m Drilled pipe 60 mm D = 3,5 m PVC 100 mm Drilled pipe 60 mm D = 5,0m

61 5.9 Example of eliminating radon bridges in CZ During active ventilation indoor radon concentration decreased to the values below 100 Bq/m 3. Fan in operation lowest speed Fan in operation lowest speed

62 6. SUB-SLAB DEPRESSURIZATION The principle of SSD methods is to change the pressure difference between the soil and the house, i.e. to lower the air pressure in the soil under the house compared to the pressure indoors and to dilute the subsoil radon concentration. The pressure is lowered by means of the natural draft occurring as a result of the stack effect and wind forces, or by a fan.

63 6. SUB-SLAB DEPRESSURIZATION Systems suitable for new buildings Radon sumps Network of flexible perforated pipes inserted into the drainage layer Combination of the above stated measures

64 6. SUB-SLAB DEPRESSURIZATION General design rules The form of soil depressurization depends on: - ratio of underfloor layer and soil permeabilities k d /k s - airtightness of floors - type and geometry of foundations A sump or a perforate pipe must be laid in every subfloor space surrounded by strip foundations. In order to minimize the occurrence of negative side effects (drying and freezing of the subsoil) the distance of a sump or a pipe from perimeter foundations should be at least 0,5 m.

65 6. SUB-SLAB DEPRESSURIZATION General design rules Passive extraction of the soil air using vertical exhaust pipe terminating above the roof should be preferred. Each passive system must enable the supplementary assembly of a fan to increase the system s efficiency. To avoid re-entering of radon into a building, the outlets of the exhaust pipes should be located at least 2 m away from windows, vent holes and inlets of HVAC systems.

66 6. BEHAVIOUR OF SSD SYSTEMS Highly permeable soil Upper layer high permeability, lower layer low permeability Rn concentration Rn concentration Air flow Air flow Air pressure Air pressure

67 6.1 Sump systems Sump is a free air space below the building s floor with a volume of at least 10 dm 3 Sump is always created in a drainage layer of coarse gravel One sump is effective over a floor area of approx m 2 Sump should be preferably placed into the centre of the underfloor space If the underfloor space is divided by strip foundations into several compartments, sump must be placed into each compartment.

68 6.1 Sump systems Sump construction Made in situ using bricks with air gaps left between them Preformed plastic components

69 6.1 Sump systems

70 6.1 Sump systems Standby sump system with pipework terminating in the footpath The system is activated when the indoor Rn level exceeds the required value.

71 6.1 Sump systems Example of a prefabricated sump from Ireland By: Radon Control Systems, IRL

72 6.1 Sump systems Example of a prefabricated sump from Ireland By: Radon Control Systems, IRL

73 6.2 SSD systems with perforated pipes Diameter of perforated pipes: mm for natural ventilation mm for forced ventilation Pipes are placed into a continuous drainage layer with a minimum thickness of 150 mm created from coarse gravel fraction of 16/32 mm. Pipes are laid in every section bordered by the strip foundations. Mutual distance between perforated pipes is around 4 m Perforated pipes ensure better pressure distribution than sumps, therefore they are more convenient for highly permeable soils.

74 6.2 SSD systems with perforated pipes

75 6.2 SSD systems with perforated pipes

76 6.2 SSD systems with perforated pipes

77 6.2 SSD systems with perforated pipes Ventilation merely to the perimeter walls is unacceptable

78 6.2 SSD systems with perforated pipes

79 6.3 Fans suitable for SSD systems Fans must be able to: transport soil air with a relative humidity from 80 % to 100 % resist the flow of condensed water resist the increased dustiness of the transported air

80 Pressure (Pa) 6.3 Fans suitable for SSD systems Typical pressure / air flow characteristics Air flow (m 3 /h)

81 6.3 Fans suitable for SSD systems Types of fans Paddle-wheel fans for longer piping and greater pressure loss Roof fans for longer piping and greater pressure loss Axial fans are not convenient they do not generate sufficient pressure

82 6.3 Fans suitable for SSD systems Typical installations of fans Wall type of a paddlewheel fan Risk of icing on the external surface of the wall from condensed water vapour

83 6.3 Fans suitable for SSD systems Roof fan Ventilating head Exhaust pipe In line paddlewheel fan

84 7. AIR GAPS DEPRESSURIZATION The principle of an air gap depressurization is to lower the air pressure in the gap that is provided along walls and floors in contact with soil. The pressure is usually lowered by means of a fan.

85 7. AIR GAPS DEPRESSURIZATION The air gap must be continuous throughout the entire area of the constructions in contact with the soil. Active ventilation is preferred. Active ventilation is executed without any vent holes delivering external air into the gap. Passive ventilation must be always executed using vertical exhaust pipes. Passive ventilation merely to the perimeter walls is unacceptable. Passive ventilation with indoor air is not allowed.

86 7. AIR GAPS DEPRESSURIZATION Air gaps construction Plastic membranes with dimples Corrugated steel, cement-fibre or plastic sheets Preformed plastic components

87 7. AIR GAPS DEPRESSURIZATION An air gap below the radon-proof membrane Radonproof membrane Exhaust pipe Airtight pipe penetration Vent holes Air gap Concrete base

88 8. HOUSES ON CRAWL SPACES 8.1 Ventilating with outdoor air Optional paddlewheel fan Optional axial fan

89 8. HOUSES ON CRAWL SPACES 8.2 Ventilating with indoor air Paddle-wheel fan Beware of water vapour condensation. Cold surfaces within the crawl space should be thermally insulated. Backflow preventer

90 8. HOUSES ON CRAWL SPACES 8.3 Sealing the ground surface Concrete slab with sealed joints to the walls Polymeric membrane with sealed joints to the walls

91 8. HOUSES ON CRAWL SPACES 8.4 Lowering the air pressure under the sealed ground surface Polymeric membrane with sealed joints to the walls Paddle-wheel fan Drainage pipes

92 8. HOUSES ON CRAWL SPACES 8.5 Sealing the floor above the crawl space In case of suspended timber floors application of radon-proof insulation should not result in unacceptable condensation of water vapour within the floor!!! Radon-proof insulation laid also under the walls

93 8. HOUSES ON CRAWL SPACES 8.6 General principles The entrance to the crawl space is recommended to be located from outside Water and wastewater pipes passing through the crawl space are to be fitted with thermal insulation When ventilating the crawl space with outdoor air, outer walls and the floor above the space must be equipped with thermal insulation When ventilating the crawl space with indoor air, outer walls and the ground surface must be provided with thermal insulation

94 8. HOUSES ON CRAWL SPACES 8.7 Example of a possible solution from UK By: Chris Scivyer, BRE, UK

95 8. HOUSES ON CRAWL SPACES 8.8 Preventing mold / fungus in naturally ventilated crawl spaces - Scandinavian solution Wooden construction above the crawl space. By: Aleksandar Birovljev, Eurofins Radonlab AS, Norway

96 9. VENTILATION SYSTEMS The principle of ventilation is to dilute radon concentration by increasing the ventilation rate Radon concentration C J n. Radon supply rate Ventilation rate V Interior air volume

97 9. VENTILATION SYSTEMS The preference should be given to systems that are balanced (amounts of supply and exhaust air are the same), or to systems creating a slight underpressure. Systems creating overpressure are not recommended in countries with cold climates (condensation in walls problems). If energy saving is important demand controlled ventilation systems should be used. Required amount of fresh air is provided only when it is needed (when the rooms are occupied). However, the ventilation should be functioning at reduced speed the rest of the time.

98 9. VENTILATION SYSTEMS 9.1 Natural ventilation supported by outdoor air inlets Types of outdoor air inlets: Outdoor air inlet Window registers for installation in window frames Wall registers for installation in external walls

99 9. VENTILATION SYSTEMS Window registers Air flow through the inlets can be adjusted: manually by the owner Flow rate (m3/h) Pressure difference (Pa) Wall registers automatically in dependence on the indoor air humidity Max. air flow rate 35 m3/h Min. air flow rate 5 m3/h Indoor air rel. humidity (%)

100 9. VENTILATION SYSTEMS Window registers Wall registers Interior side Exterior side

101 9. VENTILATION SYSTEMS Legend: OVS outdoor air inlet LIVING ROOM HALL KITCHEN ENTRANCE TECH. ROOM

102 9. VENTILATION SYSTEMS 9.2 Mechanical exhaust air ventilation (hybrid ventilation) with outdoor air inlets Hybrid or exhaust fan Outdoor air inlet Exhaust unit

103 9. VENTILATION SYSTEMS Exhaust units Exhaust unit with presence detection Humidity senzitive exhaust unit They open only when the ventilation is needed - demand control ventilation.

104 9. VENTILATION SYSTEMS Fans suitable for exhaust ventilation Fans for several exhaust units Hybrid fans installed at the top of the exhaust pipe create a complementary pressure when the natural draught is not sufficient

105 9. VENTILATION SYSTEMS Legend: OVS outdoor air inlet OS exhaust fan 1 humidity sensitive exhaust unit LIVING ROOM ENTRANCE CORRIDOR BEDROOM 2 - exhaust unit with presence detection KITCHEN BEDROOM

106 9. VENTILATION SYSTEMS 9.3 Mechanical supply and exhaust air ventilation Ventilation unit with filters, heat exchanger, preheater and fans. Due to energy costs the ventilation rate should not exceed 1,0 h -1, otherwise supplementary measures (sealing of the substructure) should be adopted.

107 9. VENTILATION SYSTEMS Legend: VJR ventilation unit with heat recovery LIVING ROOM ENTRANCE BEDROOM CORRIDOR KITCHEN BEDROOM

108 9. VENTILATION SYSTEMS 9.5 Examples of balanced, supply and exhaust air, heat recovery ventilation units (HRV) Cross flow heat exchanger Rotating heat exchanger By: Aleksandar Birovljev, Eurofins Radonlab AS, Norway

109 9. VENTILATION SYSTEMS 9.6 Mini balanced supply and exhaust air ventilation with heat exchange hidden in walls By: Aleksandar Birovljev, Eurofins Radonlab AS, Norway

110 9. VENTILATION SYSTEMS Exhaust air should not be mixed with supply air!!! Air mixing decreases the effectiveness of ventilation in reducing radon concentration.