PREDICTION AND MANAGEMENT OF EMERGENT NOISE IN THE TOMORROW S SUSTAINABLE CITY

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1 PREDICTION AND MANAGEMENT OF EMERGENT NOISE IN THE TOMORROW S SUSTAINABLE CITY Jérôme DEFRANCE; Romain DUMOULIN Affiliation: {CSTB, rue Joseph Fourier, 3 Saint-Martin-d Hères, France} {jerome.defrance@cstb.fr; dumoulin.romain@hotmail.fr} Abstract In this research we attempt to assess the potential noise emergence due to the installation of building equipments dedicated to energy efficiency in the context of sustainable development of tomorrow s city centers. We first try to predict the global background noise due to ground transportation in a tomorrow s sustainable main boulevard. To do so we assume drastic changes of surface mobility: limitation of gas vehicles, introduction of electric ones, development of tramways and increased use of two-wheelers etc. This leads us to consider a set of possible traffic scenarios. In a second step we model different building equipment s noise sources such as small urban wind turbines and heat pumps. Again different building scenarios are addressed. Depending on the time period as well as the receiver position (pedestrian, building façade or backyard), the impact of these building sources is finally determined by using MITHRA ray-tracing code, for different transportation/building equipments realistic scenarios. Results are given in terms of noise emergence compared to quiet buildings situations, especially at night. Keywords: Environmental noise, urban noise, urban wind turbine noise, electric car noise, building energy equipments noise, sustainable development of cities 1 Introduction In this early 1 st Century, France is under a triple economy-ecology-energy crisis. From urban acoustics point of view, the energy crisis should lead to: The decreasing of classical urban traffic (fuel cars and lorries) in city centers, The emergence of new types of noise: due to the forecast abatement of surface transport background noise and densification of cities, new noises from human activities as well as new building energy equipment should arise. 1

2 INTERNOISE 1 JUNE 13-1 LISBON PORTUGAL This research presents some works about these two points, aiming at answering the following questions: What are the possible scenarios of road traffic noise abatement in city centers in the next decades? What are the new building noise sources? And what are their emergence conditions? What could be the consequences on the urban planning of tomorrow s sustainable cities? Future possible background noise.1 Electric car noise emission One major predicted change in urban road traffic noise composition is the introduction of electric cars. In order to take into account electric light vehicles in our MITHRA software simulations we follow the assumption of a mean noise abatement of db(a) at 5 km/h and 5 db(a) at 3 km/h compared with a classical fuel car (values from [1], see Figure 1). All simulations have been carried out using the NMPB-9 model. Figure 1 LAmax for several types of light vehicles vs speed, from [1]. Future possible traffic scenarios Different possible future traffic scenarios are considered here (Heavy vehicles ban, electric light vehicle only, speed limit reduction). They are recapped in Table 1. Table 1 Future studied traffic scenarios Description Speed Traffic distribution Current 5 km/h : 9% (5%) : 91% : % Speed reduction 3 : 9% (5%) : 91% : % Electric LV with HV 5 : 9% : % : 1 % Current. No HV 5 : % : 1% : % : HV : LV : electric LV -db Scenario 5 : % : % : 1 % Scenario 3 3 : % : % : 1 %

3 INTERNOISE 1 JUNE 13-1 LISBON PORTUGAL.3 Application to a real A realistic application is carried out on the Cours Jean-Jaurès in Grenoble (France) called hereafter the. It is a typical Haussmanian (Parisian) avenue and is said to be the straightest avenue in Europe ( km long). Its width within the studied area is about m and buildings height about 1 m. Measurements at the 1 st floor at m in front of a typical Haussmanian building are also made in order to get mean LAeq values for different periods of the day: early morning (:- :), day (:-:), evening (:-:) and night (:-:) (see Fig. ). Figure From left to right: top view of, measurement site with microphone and typical LAeq evolution from 19: to 1: at first floor The following parameter study is focused on a few receivers of interest: pedestrians along the and in the backyard (1,5 m high), and the façade ( m in front of it at 3 rd and 5 th levels) facing the and facing the backyard (Fig. 3). Façade pedestrian Façade pedestrian Figure 3 Receivers of interest 3

4 INTERNOISE 1 JUNE 13-1 LISBON PORTUGAL 3 Noise Emergence of building energy equipments 3.1 Heat pumps Installation of new heat pumps often leads to many complaints. Sound power levels used in our simulations are those measured by the CETIAT (Centre technique des industries aérauliques et thermiques) for the heat pump Altherma by Daikin (Lw = db(a)). One may note that results given hereafter may correspond to extreme non-realistic cases. Figure Example of massive installation of heat pumps on façade (left). Modeling into MITHRA software of 5 heat pumps installed on the façade (right) Installing heat pumps on boulevard façade The emergences remain very weak (Fig. 5): traffic noise is dominent, even in the case of an extreme installation with 5 heat pumps on the façade (Fig. ) working 1% time (which is the case for very cold and hot weathers only) 3 Early morning Night Night 3 km/h Night Scenario Night Scenario 3,5 1,5 1,5 Grnd floor Figure 5 Emergence in db(a) due to the installation of 5 heat pumps on façade working 1% time

5 INTERNOISE 1 JUNE 13-1 LISBON PORTUGAL 3.1. Installing heat pumps on backyard façade The building acts as a noise barrier: background noise abatement between the façades are in the order of db(a). The consequence is that emergence of heat pumps noise is very important on the backyard façade (maximum at ). Figure shows emergence results for the extreme case of 11 heat pumps on the inner courtyard façade (one per flat) working 1% time. On the façade, the emergence is zero. In Fig. 7, one shows for different background noise scenarios the evolution of noise emergence at the 3 rd backyard floor when number of installed heat pumps decreases. Day Early morning Night Night 3 km/h Night scenario Night scenario 3,,,,, 1, 1, 1, 1, 1,,,,,, Figure Emergence in db(a) due to the installation of 11 heat pumps on backyard façade working 1% time, vs background noise scenario and receiver Day Early morning & even. Night Night 3 km/h Night Scenario Night Scenario Number of heat pumps installed on the backyard façade ' Figure 7 Emergence in db(a) at the on backyard vs number of heat pumps installed depending of background noise scenario 5

6 INTERNOISE 1 JUNE 13-1 LISBON PORTUGAL 3,5 3,5 1,5 Backyd 5th floor Backyd 5th floor Blvd Blvd 3rd floor Backyd 3rd floor Blvd Night "3 km/h" Night Scenario Night Scenario 3 1,5 Early morning Night Noise level Difference in db(a) vs background noise for a "daytime traffic" -1 Figure Emergence in db(a) due to the installation of 5 outdoor heat pumps on the façade (working 1% time) vs noise level difference in db(a) compared to background noise for a "daytime traffic" 1 1 Backyd 5th floor Backyd 5th floor Blvd Blvd 3rd floor Backyd 3rd floor Blvd Night Scenario 3 1 Night Scenario 1 Night 1 Night"3km/h" Early morning Noise level Difference in db(a) vs background noise for a "daytime traffic" Figure 9 Emergence in db(a) due to the installation of 11 outdoor heat pumps on the façade (working 1% time) vs noise level difference in db(a) compared to background noise for a "daytime traffic" Fig. and Fig. 9 shows the evolution at different receivers of the emergence due to the installation of 5 and 11 outdoor heat pumps on the façade (working 1% time) vs noise level difference compared to background noise for a "daytime traffic" (linked to the traffic scenarios). 3. Mechanical Extract Ventilation (MEV) We consider one MEV system per flat and that the extraction is located on the roof. The calculations are carried out considering the models CVEC (for 1 flats) and VEC 31B (for flats) from Aldes. Sound power levels are 3. and 7. db(a), respectively. One may note that the results given hereafter may correspond to extreme non-realistic cases. In Fig. 1, calculated emergences are shown: they are relatively weak on the side (less than db(a) for an extreme scenario); they may reach 1 db(a) on the backyard side for the lowest background noise periods (Night scenario 3).

7 INTERNOISE 1 JUNE 13-1 LISBON PORTUGAL Day Early morning&even. Night Night 3 km/h NightScenario Night Scenario Figure 1 Emergence in db(a) due to the installation of 1 mechanical ventilation per flat on, vs background noise and receiver We also give in Fig. 11 the evolution at different receivers of the emergence due to the installation of one mechanical ventilation per flat vs noise level difference compared to background noise for a "daytime traffic" (linked to the traffic scenarios) Backyd 3rd floor Backyd 5th floor Backyd 5th floor Blvd 3rd floor Blvd Blvd Night"3km/h" Night Scenario Night Scenario 3 Early morning Night Noise level Difference in db(a) vs background noise for a "daytime traffic" Figure 11 Emergence in db(a) due to the installation of 1 mechanical ventilation per flat vs noise level difference in db(a) compared to background noise for a "daytime traffic" 7

8 INTERNOISE 1 JUNE 13-1 LISBON PORTUGAL 3.3 Urban wind turbines Installing wind turbines on a block means to respect some basic construction rules: Height of mast: 3 or meters, however m high is the most commonly used, Minimum distance between wind turbines: 9.3 meters. The studied wind turbine here is the vertical axis QuietRevolution qr5 with a mean sound power level of L w = 7.3 db(a). This value has been determined from the two following measurement campaigns: A campaign dedicated to the determination of the qr5 wind turbine sound power level for different wind speeds [], A 3-month campaign [3] of wind speed measurement at the top of a -floor building in Lyon (France, close to Grenoble) (Fig. 1). Figure 1 Distribution of mean wind speeds measured during 3 months at the top of a -floor building in Lyon [3] One may note that the results given hereafter may correspond to extreme non-realistic cases. We study first an installation of 3 wind turbines in line over one roof of the square block. In Fig. 13 are shown the emergences calculated for different receivers and background noise scenarios. For the current night level, the 3 db(a) are reached only the facing backyard. The highest emergences are observed for traffic night scenarios and 3, between and 1 db(a) on the backyard side. Day Early morning&even. Night Night Scenario Night Scenario Figure 13 Emergence in db(a) due to the installation of 3 Quiet Revolution wind turbines, vs background noise scenario and receiver

9 INTERNOISE 1 JUNE 13-1 LISBON PORTUGAL night scenario 3 night scenario night Early morning&even. Day Number of installed wind turbines within the block Figure 1 Emergence in db(a) at the on backyard façade vs number of installed wind turbines for different background noise scenarios Figure 1 presents for different background noise scenarios the evolution of the emergence calculated at the on backyard façade when number of installed wind turbines is decreasing. We also give in Fig. 15 the evolution at different receivers of the emergence due to the installation three Quiet Revolution wind turbines vs noise level difference compared to background noise for a "daytime traffic" (linked to the traffic scenarios). Backyd Night Scenario 3 1 3rd floor Backyd 1 1 5th floor Backyd 5th floor Blvd 3rd floor Blvd Night"3km/h" Night Scenario 1 Blvd Night 1 Early morning Noise level Difference in db(a) compared to background noise for a "daytime traffic" -1 Figure 15 Emergence in db(a) due to the installation of 3 Quiet Revolution wind turbines vs noise level difference in db(a) compared to background noise for a "daytime traffic" 9

10 INTERNOISE 1 JUNE 13-1 LISBON PORTUGAL Conclusions The research has shown that the emergence is strongly linked to: The future road traffic scenario, The localisation of the noisy equipments on the buildings, The façade considered. On the backyard side the maximum admissible values of noise emergence is exceeded in many cases. On the side the emergence is often weak. Highest values of calculated emergences have to be moderated since they have been obtained considering extreme scenarios of equipment installation and very low background noise (ignoring other possible urban source of noise). Actually for the Night scenario 3 background sound levels calculated on the backyard façade are around 3 db(a): a noisy road axis (out of the studied district) even if remote could then bring significant extra acoustical energy and decrease the predicted emergences. A more global study over a larger area should then be necessary. Work is still in progress on 3D sound restitution of such future road/building noise scenarios, making possible the comparison by listening of the urban acoustical situation of today and that of tomorrow. And why not that of 1 years ago (Fig. 1)? Figure 1 Cours Jean-Jaurès in 191 References [1] Lelong, J; Michelet, R. Passenger cars. Power unit and tyre-road noise, driving behaviour: what are the stakes? InterNoise1, The Hague, The Netherlands, Aug.1 [] qr5 v1. VAWT Wind turbine noise measurements, Consultancy Noise Measurement Report ref.737-r1, December 7 Institute of Sound & Vibration Resear. Consulting [3] Reports on the feasibility study, WINEUR Project, Deliverable 5., February 7 1