Comparison of measured and predicted sound insulation for a thermal retrofitted building

Transcription

1 Comparison of measured and predicted sound insulation for a thermal retrofitted building C. Guigou-Carter, R. Foret, R. Wetta,P. Ducruet, M. Villot CSTB Inter-Noise 2010 Lisbon, Portugal PAGE 1

2 Introduction In Europe, building sector is associated to the majority of energy consumption, especially space heating. High saving potential for primary energy use in the field of building retrofit rather than in the field of new buildings Ongoing project, several types of buildings corresponding to different building periods, buildings techniques are considered and the effect of thermal retrofit on acoustic performance of buildings is investigated. In-situ measurements to determine the effect of thermal retrofit on acoustic performance of the selected building from the late 70s are presented. CSTB ACOUBAT software is used to predict thermal retrofit effect on building acoustic performance and to analyze it in terms of different transmission paths to identify effect of different thermal retrofit elements Inter-Noise 2010 Lisbon, Portugal PAGE 2

3 Building description Two identical buildings for social housing 4 floors 20 dwellings in each building Underground parking garage Inter-Noise 2010 Lisbon, Portugal PAGE 3

4 Building description Façade walls as well as the dwelling separating walls are made of 17 cm thick concrete Thermal lining, composed of 80 mm expanded polystyrene layer with a 10 mm thick gypsum board, is placed on façade wall. All the floor slabs are constructed of concrete 20 cm in thickness ; concrete floor covered with a basic plastic floor covering in living rooms and kitchens, and a textile floor covering in bedrooms Lower floor slab (separating non heated parking garage and ground floor dwellings) is treated with sandwich panel composed a layer of polystyrene and a finish layer of wood fibers wool Windows and door windows are 4/8/4 double glass pane, with frame mounted air inlet Inter-Noise 2010 Lisbon, Portugal PAGE 4

5 Building measurements Dwellings available for measurements : 2 bedroom duplex apartment and 2 bedroom apartment in building corner (2 façade wall), on ground floor Duplex apartment : airborne acoustic insulation with respect to the exterior noise, in the living room (18 m 2 ) associated to an important window surface, in the kitchen (10 m 2 ) with a door window and in the bedrooms associated with an equivalent surface of window and opaque surface area; and vertical airborne sound insulation due to its configuration and structure representative of vertically superposed apartments Apartment located in the building corner had the advantage to include a bedroom (11 m 2 ) with a complete opaque surface area and a window on the other corner side, as well as a bedroom (9 m 2 ) with an equivalent surface of window and opaque surface area Inter-Noise 2010 Lisbon, Portugal PAGE 5

6 Thermal retrofit description External walls treated with an external thermal insulation composite system (ETICS) composed of a 120 mm expanded polystyrene layer with a 6 mm thick plaster finish Windows and door windows substituted with standard double panes (4 mm glass / 16 mm cavity / 4 mm glass) including frame mounted hygroscopic regulated air inlet. Thermal bridges associated to balconies have not been taken into account by the persons in charge of selecting the thermal insulation for this building retrofit. Therefore, even if the energy consumption is decreased by the implement thermal retrofit, it is definitely not optimized. Furthermore, due to economic reasons the thermal treatment on the lower floor slab (non heated parking garage) was not modified Inter-Noise 2010 Lisbon, Portugal PAGE 6

7 Acoustic measurements and prediction Acoustic insulation measurements were realized following the standard EN ISO 10052, performed for the third octave bands from 100 to 0 Hz, including reverberation time measurement CSTB ACOUBAT software based on the EN , -2, -3 and -6 standards [4] and a large product database is used to evaluate the building acoustic performance with respect to the French acoustic regulation. For this project, predicted retrofitted building performance compared to measured one. If product acoustic performance is not part of ACOUBAT database or available from laboratory measurements, then CSTB AcouSys software based on TMM is used to predict sound transmission, sound absorption, impact noise and rainfall noise of building elements. Inter-Noise 2010 Lisbon, Portugal PAGE 7

8 Building configurations (a) Bedroom (18 m 2 ) Bedroom (10 m 2 ) (b) Bedroom (9 m 2 ) Bedroom (11 m 2 ) Living room (18 m 2 ) Kitchen (10 m 2 ) Duplex apartment with a kitchen and living room, and 2 bedrooms above Building corner apartment Inter-Noise 2010 Lisbon, Portugal PAGE 8

9 R (db) Façade wall thermal retrofit Acoustic performance R was measured for a mm EPS ETICS bounded on mm thick concrete wall according to ISO 1-16 Measured performance compared to AcouSys software predicted performance : trends were well captured over the complete frequency range Hz AcouSys software used for 120 mm thick EPS exterior lining implemented on actual building System resonance frequency around Hz with 13 db decrease in the supporting wall acoustic performance appears. Global performance index (R w +C) is negative at -5 db Inter-Noise 2010 Lisbon, Portugal PAGE 9

10 R (db) D n,e (db) Windows thermal retrofit Original situation - 4/8/4 Rw+Ctr=26 db After thermal retrofit - 4/16/4 Rw+Ctr= db 50 Original situation - Dn,e,w+Ctr =36 db After thermal retrofit - Dn,e,w+Ctr = db Inter-Noise 2010 Lisbon, Portugal PAGE 10

11 D nt (db) D nt (db) D nt (db) Façade sound insulation Measurements Duplex apartment Living room Kitchen Small bedroom Original situation After thermal retrofit 50 Original situation After thermal retrofit 50 Original situation After thermal retrofit Thermal retrofit is quite beneficial on the façade sound insulation; an improvement of 4 to 5 db is achieved in the D nt,a,tr. Inter-Noise 2010 Lisbon, Portugal PAGE 11

12 D nt (db) Façade sound insulation Measurements/Predictions 60 Original situation - Measurement Original situation - Prediction 50 After thermal retrofit - Measurement After thermal retrofit - Prediction Duplex apartment / Small Bedroom Improvement relatively well predicted compared to measurements Original situation : window is associated to the most dominant path in the low-mid frequency range (up to about 1 khz), while the air-inlet becomes dominant at high frequencies (above 1 khz) After thermal renovation : both window and air-inlet are important in high frequency range (above 1 khz); as before in the low-mid frequency range the path through the window is dominant Effect exterior thermal lining minimal Inter-Noise 2010 Lisbon, Portugal PAGE 12

13 Façade sound insulation Original situation Retrofitted situation Room Measurement Prediction Measurement Prediction Living room Kitchen Small bedroom Large Bedroom Façade sound insulation of building in original situation appears to be relatively good, close to the actual acoustic regulation ( db) Thermal retrofit associated to D nt,a,tr improvement of 4 to 5 db In terms of global index D nt,a,tr, the prediction tool provides a fairly good estimate of the improvement associated to the thermal renovation with respect to the original situation Global index obtained from prediction is generally higher than that obtained from the measurements Inter-Noise 2010 Lisbon, Portugal PAGE 13

14 D nt (db) Airborne sound insulation Measurements/Predictions 90 Original situation 80 After thermal retrofit ACOUBAT Prediction Duplex apartment Vertical Kitchen-Small Bedroom For prediction of interior airborne sound insulation the external thermal insulation ETICS is not considered to have any effect since no modification of lateral transmission paths Comparison between measurements and prediction is quite satisfactory : D nt,a 58 against 56 db; thermal retrofit has no effect on acoustic performance Direct path through the floor is dominant Difference in low frequency range : floor covering performance Difference in high frequency range : duplex apartment staircase and doors Inter-Noise 2010 Lisbon, Portugal PAGE 14

15 Conclusions Effect of thermal retrofit on acoustic performance of a building from the late 70s, concrete based has been investigated Thermal retrofit includes the addition of PSE ETICS applied on building façade and replacement of windows and air inlets Effect of thermal retrofit on acoustic performance was measured and predicted with CSTB developed ACOUBAT software Measurements and predictions compared fairly well. Change in window and air-inlet has important and positive effect on façade sound insulation Measurements demonstrate that the external thermal insulation ETICS has no or very little effect on the airborne sound insulation Improvement of façade sound insulation associated to thermal retrofit can yield to unbalanced acoustic contribution between noise from indoor and outdoor leading to acoustic discomfort Building types from older time periods are under investigation Inter-Noise 2010 Lisbon, Portugal PAGE 15