Acoustic performance of dwellings and specifics for lightweight constructions Professor Eddy Gerretsen
Content Introduction Performance quantities Construction principles What performance is required Does heavy or leightweight matter?
Introduction Acoustic performance is an important aspect of dwellings, affecting the health and comfort of the residents It concerns sound from neighbours: TV, singing, walking, dancing.. service equipment: toilet, heating installation outside: road traffic, playing children, dogs
Introduction Every country expresses the requirements in these areas differently, though a so-called COST action tries to harmonize this for the future But fortunately the basic quantities behind these requirements are essentially the same.
Introduction Building Acoustic quantities are already used since more than 50 years and are not depending on material but just the performance.. But current requirements are mainly based on experience in traditional buildings, that is mostly heavy materials like brick and concrete
Introduction Light weight building elements and construction methods become more and more popular transportation costs, prefab & mounting, sustainability, flexibility, extending existing buildings,... Thus a big question is: does heavy or lightweight matter?
Performance quantities Airborne sound: level difference between rooms, standardized to reverberation time: D nt,a assuming normal behaviour of neighbours, this gives an indication of the received sound levels, related to the subjective assessment
Performance quantities Impact sound: level due to standardized tapping machine: LnT,A which assessed appropriately can be interpreted as the sound levels due to human walking Sound from outdoors and equipment not considered today
principles for traditional heavy buildings traditional buildings: for better sound insulation heavier walls and floors reduce indirect transmission through lighter inner walls, floors and façade
principles for traditional heavy buildings traditional buildings, for instance: separating wall or floor at least > 500 kg/m 2, possibly heavier f.i. 250 mm concrete heavy cavity wall with disconnected walls etc. measures to reduce indirect transmission resilient material details ground floor junction
principles for lightweight buildings lightweight buildings: separate elements, use wide cavities, minimize contacts apply two or three layers, resiliently mounted use dilatation for inner walls and façade
principles for lightweight buildings lightweight buildings, for instance: two sides 2x12,5 mm gypsum, 250 mm cavity with mineral wool wood joist floor, with independent ceiling at 400 mm and floating floor on top
80 airborne sound normal range 100-3150 Hz 70 level difference [db] 60 50 40 30 20 concrete 550 kg/m2; DnTA=58 / 58 63 125 250 500 1000 2000 4000 frequency [Hz] 250 mm concrete
airborne sound level difference [db] 80 70 60 50 40 double; 75 kg/m2; DnTA=62 / 61 30 double; 50 kg/m2; DnTA=60 / 54 concrete 550 kg/m2; DnTA=58 / 58 20 63 125 250 500 1000 2000 4000 frequency [Hz] normal range 100-3150 Hz even better in this range dip at lower frequencies D nta-63 Hz : 1-6 db worse so consider at least 63 Hz for equal performance as heavy wall 2x12,5 mm gypsum board 100 mm minerale wol
impact sound 80 70 concrete; LnTA= 55 / 55 + carpet; LnTA= 51 / 51 normal range 100-3150 Hz impact level [db] 60 50 40 30 250 mm concrete 20 63 125 250 500 1000 2000 4000 frequency [Hz]
impact sound impact level [db] 80 70 60 50 40 30 wood joist; LnTA= 55 / 61 + carpet; LnTA= 55 / 61 concrete; LnTA= 55 / 55 + carpet; LnTA= 51 / 51 normal range 100-3150 Hz booming walking sound L nta-63 Hz : 3-6 db worse carpet does not help consider at least 63 Hz for equal performance 31 Hz probably not relevant, but 10 Hz vibrations? 20 63 125 250 500 1000 2000 4000 frequency [Hz]
impact vibrations walking induced vibrations relevant - own floor: require sufficient stiffness (f res ) - neighbours floor: also junction attenuation needed OneStep RMS [mm/s] OneStep RMS [mm/s] 6 5 4 3 2 1 0 1 0,8 0,6 0,4 0,2 own concrete light-v2 light-v3 light-v4 light-v5 neighbour general quantity (could be) velocity by one foot step experiments with floors and junctions often still too high, both on own and neighbours floor indications on how to improve designs also relevant for some equipment, i.e washing machine 0 concrete light-v2 light-v3 light-v4 light-v5
does heavy or lightweight matter? it is essential to take into account lower frequencies, preferably for airborne and necessary for impact sound insulation additionally, walking and equipment induced vibrations need to be considered and treated
does heavy or lightweight matter? with lightweight, multiple constructions, equal or even better acoustic performance is possible but, if for lightweight buildings only the current requirements are used, it means big trouble
Thank you for your attention