1 Danish Wind Industry Association Danish Wind Turbine Owners' Association Low Frequency Noise from Wind Turbines: Do the Danish Regulations Have Any Impact? An analysis of noise measurements. January 2014 Published : 9 January 2014 Project : Prepared : Bo Søndergaard Checked : Peter Henningsen Acoustica Akustik Støj Vibrationer Dusager 12 Tlf Web CVR-nr Aarhus N Direkte tlf Danmark Mobiltlf File Report Low frequency noise from wind turbines.docx
2 Page 1 FOREWORD At the wind turbine noise conference in Denver august 2013 Bo Søndergaard from Grontmij s acoustics department, Acoustica, presented results from an investigation of old and new measurements of noise from wind turbines . As this investigation was made without any funding with the purpose to present most recent findings at the conference no formal reporting was made at that time. Danish Wind Industry Association and Danish Wind Turbine Owners' Association have asked Grontmij if it was possible to publish a documentation of the findings from the presentation in Denver. This report is a more detailed documentation of the presentation from Denver. The reporting is paid for by the Danish Wind Industry Association and Danish Wind Turbine Owners' Association, but the results are from the independent investigation made by Grontmij at their own expense. The acoustics department at Grontmij in Denmark, Acoustica, is an independent consultancy with a long history for working for industrial clients, environmental authorities, organisations and private clients. As a guarantee for independency and quality Acoustica holds an accreditation from the Danish Accreditation, DANAK for testing in the field of noise and acoustics. Grontmij A/S Bo Søndergaard Acoustica
3 Page 2 SUMMARY For several years the concern that low frequency noise from wind turbines could cause serious annoyance for neighbours to wind turbines has been a dominant factor in the public debate in Denmark. From the beginning of 2012 the Danish regulations were revised and a criteria for the amount of in-door low frequency noise was introduced. Results from new and old measurements of noise from mainly Danish produced wind turbines are analysed and compared with the Danish regulations for noise and low frequency noise. In most cases low frequency noise is not the decisive parameter for Danish wind farms to comply with the Danish regulations. The new data in the analysis are from existing wind turbine projects and series produced wind turbines excluding dedicated prototypes. The purpose of the analysis is to investigate whether the new Danish regulation on low frequency noise have had any impact on the emitted low frequency noise and the low frequency noise at the neighbours or not. The wind farm examples do not give a clear answer to that. However it indicates that the situation has not changed and that the amount of low frequency noise at the residents is the same as for wind farms with smaller and/or older wind turbines. The analysis of the sound power levels and sound power spectra gives more information. Analysis of the sound power spectra shows that after 2010, where it was known that low frequency regulations were likely to be introduced, the relative amount of noise in the frequency range from 100 to 400 Hz is reduced. This includes the important part of the low frequency range from 100 Hz to 160 Hz. Whether this is because of the Danish regulation is not possible to say, but it is likely, that the regulation has increased the focus on this in the design phase. From the measurements it can be seen, that the low frequency tones, which were a significant part of low frequency noise in , , ,  and  are reduced for series produced wind turbines. In general the analysis shows that the development of low frequency noise with size do not follow the conclusions from the analyses in ,  and . The analysis show that on average the amount of low frequency noise is the same for large and small wind turbines relative to the total noise level and that the amount of low frequency noise for new large wind turbines is less than for old large wind turbines relative to the total noise level. The analysis is based on a larger number of measurement reports than previous analyses and experiences from post construction documentation. The results may change with inclusion of new data, but the conclusions are in line with the general conclusions in  and , where the results were influenced by prototype wind turbines. There is a large variation in sound power levels and sound power spectra within each group of wind turbines used in the analysis and it is important to check the details for each wind farm project already in the planning phase.
4 Page 3 SUMMARY IN DANISH I adskillige år har bekymringen om, at lavfrekvent støj fra vindmøller kunne give anledning til væsentlig gene i omgivelserne, været en dominerende del af den offentlige debat i Danmark. Ved starten af 2012 blev der indført nye regler for støj fra vindmøller og grænseværdier for lavfrekvent støj blev indført. Resultater fra nye og gamle målinger af støj fra primært dansk producerede vindmøller er blevet analyseret og sammenlignet med de danske regler for støj og lavfrekvent støj. I de fleste tilfælde er det ikke den lavfrekvente del af støjen, der er afgørende for om et projekt kan overholde de danske regler. Data der indgår i sammenligningen er fra eksisterende vindmølleprojekter og serie producerede vindmøller. Dedikerede prototyper er udeladt fra analyserne, da de ikke vurderes at være repræsentative for de opstillede vindmøller. Formålet med analysen er at undersøge, om de nye regler for lavfrekvent støj har haft indflydelse på den udsendte lavfrekvente støj fra vindmøllerne og den lavfrekvente støj ved naboerne. Analyserne, baseret på vindmølleparker, giver ikke noget entydigt svar, men det ser ud til at forholdene ikke er ændret væsentligt og at andelen af lavfrekvent støj er af samme størrelsesorden som for vindmølleparker med mindre og/eller ældre vindmøller. Analysen af lydeffektniveauer og lydeffektspektre giver mere detaljeret information. Analysen af lydeffektspektre viser, at efter 2010, hvor det var kendt at der ville komme grænser for lavfrekvent støj, er den relative andel af støj i frekvensområdet fra 100 Hz 400 Hz reduceret. Dette omfatter den væsentlige del af det lavfrekvente frekvensområde fra 100 Hz til 160 Hz. Hvorvidt dette skyldes indførelse de nye grænseværdier, er det ikke muligt at sige, men det er sandsynligt, at reglerne har øget fokus på lavfrekvent støj i designfasen. Det er Grontmij s erfaring, at de lavfrekvente toner, som var en væsentlig del af den lavfrekvente støj i , , ,  og , er reduceret for de seriefremstillede vindmøller. Overordnet viser analysen, at udviklingen af lavfrekvent støj med størrelsen af vindmøllerne ikke følger forudsigelserne fra analyserne i ,  og , men at små og store vindmøller i gennemsnit har samme andel af lavfrekvent støj relativt til den samlede støj og at nye store vindmøller har en mindre andel af lavfrekvent støj end ældre store vindmøller relativt til den samlede støj. Analyserne er baseret på et større antal målerapporter end tidligere analyser, samt erfaringer med eftervisning af forholdene efter opstilling af vindmølleparker. Resultaterne kan ændre sig med inkludering af yderligere data, men konklusionerne er i overensstemmelse med de overordnede konklusioner in  and , hvor resultaterne var væsentligt påvirket af resultater fra prototype vindmøller. Der er stor variation i lydeffektniveauerne og lydeffektspektrene i de enkelte grupper af vindmøller og det er derfor vigtigt at vurdere detaljerne for de enkelte vindmølleprojekter allerede i planlægningsfasen.
5 Page 4 TABLE OF CONTENTS PAGE FOREWORD 1 SUMMARY 2 SUMMARY IN DANISH 3 1 INTRODUCTION 5 2 INVESTIGATIONS Noise from wind farms Noise emission from wind turbines. 7 3 OTHER CONSIDERATIONS Type of regulation Noise as a function of distance 16 4 CONCLUSIONS 17 5 REFERENCES 18
6 Page 5 1 INTRODUCTION Around low frequency noise from wind turbines became a major concern in the public in Denmark. There was a worry that larger wind turbines would emit substantially more low frequency noise than the wind turbines people knew already. As this had consequences for the development of on-shore wind energy the Danish energy authorities initiated an investigation into the topic. The results were reported in  and  by DELTA and an alternative interpretation were reported by the acoustics department at the University of Aalborg ,  and . In December 2011 the Danish regulations on wind turbine noise were revised and noise criteria was introduced for the in-door low frequency noise. Details on the regulations and the background can be seen in . Sørensen presented some of the consequences for the planning process in . In short the Danish regulation introduces a set of noise criteria as well as a method for assessing the criteria through measurements and predictions. The noise limits are described in the Statutory order 1284 of 15 December 2011 from the Danish ministry of the environment  as follows: The total noise impact from wind turbines may not exceed the following limit values: 1) At the most noise-exposed point in outdoor living area no more than 15 metres from dwellings in open countryside: (a) 44 db(a) at a wind speed of 8 m/s. (b) 42 db(a) at a wind speed of 6 m/s. 2) At the most noise-exposed point in areas with noise-sensitive land use: (a) 39 db(a) at a wind speed of 8 m/s. (b) 37 db(a) at a wind speed of 6 m/s. The total low-frequency noise from wind turbines may not exceed 20 db at a wind speed of 8 and 6 m/s indoors in dwellings in open countryside or indoors in areas with noise sensitive land use respectively. 2 INVESTIGATIONS The question now is; do the new regulations have any impact on low frequency noise from wind turbines and how can it be checked. As the neighbours are the main objective for the new regulations, a set of wind farm projects, where Grontmij has been involved in the post construction documentation of noise were reviewed. Another parameter which has been used as an indicator is the sound power level and specially the sound power spectra of the wind turbines. An analysis based on Grontmij s database on wind turbines has been made to see if there is a development. The database consists of the original data from  except for the specific prototype wind turbines. Measurement reports from the archives of Acoustica ranging back to 1988 are included and supplemented with new measurements from 2010 to 2013.
7 Page Noise from wind farms. As an independent consultancy Grontmij is often involved in post construction documentation of noise from wind farms. In Denmark this includes determination of the sound power level of individual wind turbines and prediction of the noise in the surroundings. In Figure 1 the noise contours, representing the noise limits, around a wind farm is shown. The blue line is 39 db(a), the red line is 44 db(a) and the pink line is 20 db(a) indoor low frequency noise, all at 8 m/s. Typically for the projects Grontmij has seen, the pink curve for low frequency noise is enclosed by the other curves indicating that low frequency noise is not the decisive parameter on whether the noise requirements are met or not. Figure 1. Typical noise contours for a Danish wind farm at 8 m/s. The blue line is 39 db(a), the red line is 44 db(a) and the pink line is 20 db(a) indoor low frequency noise. In Table 1 results from noise predictions for 6 wind farms according to the Danish regulations are shown. The first 3 projects are planned and erected before the regulations on low frequency noise were introduced. The last 3 were planned with the new regulations as a design criteria. Project no. 3 is actually a much older project with new measurements made in 2013, allowing for a comparison with the new criteria. The numbers in the parenthesis show the margin to the noise criteria. For the normal noise the margin is typically up to 2 db, while it is in the range of 3 to 7 db for low frequency noise. This again indicates that it is the normal noise which is the decisive parameter and not the low frequency noise. From these limited data it is difficult to conclude on the difference between older and newer projects, but it looks like low frequency noise from new and old projects is of the same order at the neighbours.
8 Page 7 Project Wind Turbines Neighbour with highest noise level Distance [m] L pa (6 m/s) [db] L pa,lf (6 m/s) [db] L pa (8 m/s) [db] L pa,lf (8 m/s) [db] 1 6 V90-3MW ,9 (2,1) 14,8 (5,2) 42,6 (1,4) 17,3 (2,7) 2 6 SWT 2, ,1 (0,9) 14,4 (5,6) 43,3 (0,7) 16,8 (3,2) kw WTG ,2 (0,8) 12,7 (7,3) 42,7 (1,3) 14,4 (5,6) 4 5 SWT ,6 (-0,6) 13,7 (6,3) 43,5 (0,5) 16,1 (3,9) 5 3 V112-3MW ,3 (0,7) 11,0 (9,0) 37,9 (1,1) 12,7 (7,3) 6 3 SWT ,4 (0,6) 12,5 (7,5) 42,1 (1,9) 14,9 (5,1) Noise criteria 42/ /39 20 Table 1. Main results from typical wind farm projects in Denmark. The numbers in parenthesis show the margin to the noise criteria. For project 4 at 6 m/s the noise is above the noise criteria. It is allowed for owners and part owners to exceed the noise criteria at their own residence. Note that the neighbour with the highest noise level is not always the neighbour with the shortest distance. For some of the projects the nearest neighbour are at a shorter distance with lower noise levels. 2.2 Noise emission from wind turbines. Much of the discussion so far has been based on sound power levels of the wind turbines and whether the wind turbines generate more low frequency noise when the size increases. For this review an analysis based on 213 measurement reports is made. All the original data from the project in  are included, except for the 4 prototype wind turbines. Data are supplemented with older measurement reports from the archives at Grontmij, where 1/3-octave band data were available, and new measurement reports. The reports represent wind turbines ranging from a few kw to the newest version of MW turbines and give the sound power spectrum at 8 m/s at 10 m height. The analysis is based on the same principles as in  to  but on a much better statistical basis with 213 measurement reports, with only 65 measurement reports in the previous analyses e.g. . As the new data also includes older types of stall regulated wind turbines with a nominal power between 2000 kw and 3000 kw sorting of data is a little different. The data are sorted into 4 groups: 200 kw, ]200 kw 1000 kw], ] kw], >2000 kw, >2000 kw old types and >2000 kw new types. This makes it possible to evaluate new large wind turbines compared to wind turbines designed and erected before the investigation in  and  was published. For comparison with previous investigations the group ]200 kw 2000 kw] is included The spectra are normalised to L WA of the individual wind turbine before averaging. A comparison of the averaged spectra for each class can be seen in Figure 2 and the number of spectra in each class can be seen in Table 2.
9 Page 8 Figure 2. Normalized apparent sound power levels in one- third-octave bands. Mean of groups of wind turbines. Error bars show ± 95 % confidence interval around the mean in every 1/3- octaveband for the group > 2000 kw. Group Number of spectra Number of spectra at 10 Hz 200 kw 16 5 ]200 kw 1000 kw] ]1000 kw 2000 kw] 27 1 > 2000 kw ]200 kw 2000 kw] > 2000 kw new > 2000 kw old 28 4 Table 2 Number of spectra in each group. As not all measurements are covering the entire frequency range the count of spectra including the 10 Hz 1/3-octave band is shown as well. All spectra are measured down to at least 50 Hz and for the new large turbines down to at least 16 Hz. The spectra representing the different groups do not deviate much in the low frequency region from 10 Hz to 160 Hz, except for the group of wind turbines below 200 kw. These turbines are relatively rare these days and due to the early design are dominated by machinery noise and tonal noise. Small wind turbines are represented by the group ] kw] which is consistent with the previous analyses in  to . In Figure 3 a comparison of the group ] kw] and the group > 2000 kw wind turbines is shown. The differences in the low frequency range are small, which can be seen in more detail in Figure 4, where the spectrum for the group > 2000 kw is subtracted from the spectrum of group ] kw]. It is clear that the group of turbines above 2000 kw deviates very little from the group ] kw] wind turbine spectrum and positive deviations are less than 1 db. In the low frequency range the difference is significant at 10 Hz, 80 Hz, 160 Hz, and 200 Hz. The statistics for all 1/3- octave bands are given in Table 3 from a Students t-test comparison of the 2 groups.
10 Page 9 Figure 3, Normalized apparent sound power levels in one- third-octave bands. Mean of two groups of turbines: ]200 kw kw] and > kw Figure 4 Normalized apparent sound power levels in one- third-octave bands. Spectrum of the group > 2000 kw wind turbines relative to the spectrum for the group ] kw] wind turbines. A positive value means that the level of group > 2000 kw at that frequency is higher than the corresponding value for group ] kw]. Error bars show 95% confidence interval around the mean in every 1/3-octaveband for the group > 2000 kw wind turbines.
11 Page 10 1/3-octave band [Hz] t d.f. single sided p 10 2,3301 7,8 0, ,5 0,4998 7,6 0, , ,1 0, , ,3 0, , ,1 0, ,5 0, ,5 0, , ,3 0, , ,0 0, , ,1 0, , ,2 0, , ,2 0, , ,5 0, , ,1 0, , ,5 0, , ,8 0, , ,2 0, , ,8 0, , ,9 0, , ,0 0, , ,2 0, , ,3 0, , ,0 0, , ,4 0, , ,2 0, , ,3 0, , ,8 0, , ,5 0, , ,5 0, , ,2 0, , ,0 0, , ,5 0,0165 Table 3. Parameters from Student s t-test comparison of group ]200 kw 2000 kw] and group >2000 kw. Figure 5 Normalized apparent sound power levels in one- third-octave bands. Mean of two groups of turbines: ]200 kw kw] and > 2000kW. The group of turbines ]200 kw kw] are shifted one third of an octave down in frequency as suggested by Møller in  and . The comparison shows that the development of low frequency noise with size is not as strong as assumed by Møller.
12 Page 11 It has been suggested by Møller in  and  that the development in low frequency noise with size corresponds to a shift by one 1/3-octave in the spectrum. In Figure 5 a comparison is made where the spectrum for the group of wind turbines ]200 kw kw] wind turbines is shifted one third of an octave down. It is obvious that the original presentation in Figure 3 gives a better match between the 2 groups and the assumption can be rejected as can the consequences of this assumption when extrapolated to 5 MW and 10 MW wind turbines. In order to investigate the results from Figure 3 further a comparison between new (after the regulation) and old (before the regulation) wind turbines from group >2000 kw is made in Figure 6. The definition of new and old is a little diffuse, but measurement reports from before 2010 are considered to be old and after 2010 as new. Around 2010 it was obvious to the industry that regulations on low frequency noise would be introduced and possible measures would be introduced. There is a clear difference in the frequency range from 100 Hz to 500 Hz where the relative amount of noise is lower for the new wind turbines than for the old wind turbines in this group. The differences are significant as can be seen in Table 4.This suggests that there is a development towards less low frequency noise, possibly because tonality in this frequency range is an area of focus for the developers. Also aerodynamic and aero acoustic optimisation of the blades tends to shift the aero acoustically generated noise towards higher frequencies. Figure 6 Normalized apparent sound power levels in one- third-octave bands. Comparison of new and old wind turbines > 2000 kw. Error bars show 95% confidence interval around the mean in every 1/3-octaveband for new wind turbines above 2000 kw
13 Page 12 1/3-octave band [Hz] t d.f. single sided p 10 0,3862 0,4-12,5 0,1210 5,2 0, ,6830 7,0 0, , ,8 0, , ,1 0, ,5 0, ,4 0, , ,3 0, , ,3 0, , ,0 0, , ,9 0, , ,1 0, , ,8 0, , ,9 0, , ,8 <0, , ,8 <0, , ,6 0, , ,4 0, , ,6 0, , ,6 <0, , ,7 0, , ,3 <0, , ,9 0, , ,8 0, , ,2 0, , ,1 0, , ,6 0, , ,4 0, , ,2 0, , ,0 0, , ,7 0, , ,7 0,0003 Table 4 Parameters from Student s t-test comparison of old and new wind turbines in the group >2000 kw. The difference is significant at frequencies 125 Hz to 400 Hz and again at 630 Hz to 1250 Hz and 8kHz and 10kHz. There are not enough measurements for old wind turbines at 10 Hz to give a result. The apparent sound power level from the measurement reports is shown as a function of nominal power in Figure 7 both as the total level, L WA and the low frequency part of the level, calculated as the sum of all 1/3-octave bands from 10 Hz to 160 Hz, L WA,LF. The figure shows that the low frequency part of the level increases at a higher rate than the total level. From a regression analysis based on wind turbines with a nominal power above 200 kw the rate is 0,43 db for each doubling of the nominal power in MW. This is a modest development compared to previous analyses of this and suggests that low frequency noise emission can be reduced. The slopes of the lines are not statistically significant different from each other [90 % confidence interval 7.2 to 10.5 for L WA and 8.6 to 11.3 for L WA,LF ]. If the tendency seen in section 2.2 continues and more new wind turbines are included in the analysis, the difference is likely to be reduced even more.
14 Sound Power Level [db re 1 pw] Page y = 8,854*log(x) + 74, y = 10,278*log(x) + 59,603 Regression LWA LWA LWA,LF Regression LWA,LF Nominal Power [kw] Figure 7 L WA and L WA,LF as a function of nominal power at 8 m/s. 3 OTHER CONSIDERATIONS 3.1 Type of regulation In this article as well as in other reviews and presentations the basis has been the sound power level at 8 m/s. This wind speed has been the reference wind speed during the period where noise from wind turbines has been measured. This is a good parameter for the new type of turbines where pitch-rpm control has taken over from stall and active stall regulation of wind turbines. Measurements where a wider wind speed range has been covered show that the pitch-rpm regulated wind turbines from group > 2000 kw, have the maximal noise emission around 8 m/s. Older wind turbines especially stall and active stall regulated wind turbines have the maximum noise emission at higher wind speeds. Sometimes the maximum may be 5 db or more higher than the value at 8 m/s. This can be seen in Figure 8, where the noise as a function of wind speed is shown for the 3 types of regulation. For comparison the curves are normalized to 0 db at 8 m/s. Experience from measurements show that the low frequency noise increases at approximately the same rate as the normal noise and older wind turbines may actually produce more low frequency noise at wind speeds above 8 m/s than the modern large pitch controlled wind turbines. It is possible that neighbours to wind farms have been exposed to more low frequency noise from the old turbines than they are from the present generation of turbines.
15 L WA re L WA.8 m/s [db] Page 14 Noise curves Modern Pitch Active stall Stall Wind speed [m/s] Figure 8. Noise curves for 3 types of wind turbines. The curves are normalised to 0 db at 8 m/s for comparison, but are from actual measurements and are examples only. In Figure 9 and Figure. 10 this is illustrated with a comparison of the spectra for a stall regulated wind turbine from group ]200 kw 1000 kw] and a pitch-rpm regulated wind turbine from group >2000 kw at 8 m/s and 10 m/s are shown. The wind turbines are selected to have comparable spectra and levels at 8 m/s. It is obvious that the noise and the low frequency noise has increased significantly for the stall regulated wind turbine compared to the pitch-rpm regulated wind turbine at 10 m/s. This is a direct consequence of the noise curves in Figure 8 and is a general trend.
16 Page 15 Figure 9. Spectra for a stall regulated wind turbine from group ]200 kw 1000 kw] and a pitch- RPM regulated wind turbine from the group > 2000 kw at 8 m/s. Figure. 10 Spectra for a stall regulated wind turbine from group ]200 kw 1000 kw] and a pitch- RPM regulated wind turbine from the group > 2000 kw at 10 m/s
17 Page Noise as a function of distance In Denmark the required distance from a wind turbine to nearest neighbour is at least 4 times the total height of the wind turbine. Low frequency noise is reduced less with the distance than higher frequencies. In Table 5 predicted values of noise and low frequency noise are presented for the groups ]200 kw to 2000 kw] and > 2000 kw wind turbines with different total heights. Mean spectra from each group are used in the predictions. The results are scaled to a noise level at the neighbour of 44 db(a) corresponding to the noise limit at 8 m/s. In the predictions the total height for group ]200 kw to 2000 kw] is 75 m (50 m hub height and 50 m rotor diameter) and 150 m for the rest of the turbines. Differences in in-door low frequency noise level are within 1.6 db. New wind turbines > 2000 kw are 0.6 db higher than small wind turbines. For wind farms the predicted levels can change with different layouts, but most often the noise is dominated by the nearest wind turbines and as the noise is reduced by 6 db from spherical spreading at all frequencies the contribution from wind turbines at larger distances will often be small. At least for typical Danish wind farms with 2 to 5 wind turbines. It is possible to design wind farm layouts that give different results, but it is chosen to use a simple example for clarity. The results in Table 5 are in line with the results from existing wind farms in Table 1. Wind Turbine ]200 kw 2000 kw] >2000 kw >2000 kw New >2000 kw Old Distance [m] L pa,lf [db re 20 µ Pa Table 5. Predicted in-door low frequency noise L pa,lf at 8 m/s for different groups of wind turbines assuming the noise level is 44 db(a).
18 Page 17 4 CONCLUSIONS The purpose of this review is to investigate if the new Danish regulation on low frequency noise has had any impact on the emitted low frequency noise and the low frequency noise at the neighbours or not. The wind farm examples do not give a clear answer. It gives the impression, that the situation has not changed and the amount of low frequency noise at the residents is the same as for wind farms with smaller and/or older wind turbines. Looking at the sound power levels and sound power spectra gives more information. Analysis of the sound power spectra shows that after 2010 the relative amount of noise in the frequency range from 100 to 400 Hz is reduced significantly. This includes the important part of the low frequency range from 100 Hz to 160 Hz. Whether this is because of the Danish regulation is impossible to say, but it is likely that the regulations have increased the focus on this in the design phase. It is the experience of Grontmij, that the low frequency tones, which were a significant part of low frequency noise in , , ,  and  are reduced for series produced wind turbines. In general the analysis shows that the development of low frequency noise with size do not follow the conclusions from the analyses in ,  and . The analysis show that on average the amount of low frequency noise is the same for large and small wind turbines, relative to the total noise level and that the amount of low frequency noise for new large wind turbines is less than for old large wind turbines, relative to the total noise level. The analysis is based on a larger number of measurement reports than previous analyses and experiences from post construction documentation. The results can change if the dataset is increased further, but the conclusions are in line with the conclusions in  and , where the results were influenced by prototype wind turbines. There is a large variation in sound power levels and sound power spectra within each group of wind turbines used in the analysis and it is important to check the details for each wind farm project. It is also important to follow the development into the next generation of wind turbines where new technologies are likely to be introduced.
19 Page 18 5 REFERENCES  Søndergaard B. Low Frequency Noise from Wind Turbines: Do the Danish Regulations Have Any Impact?, 5th International Conference on Wind Turbine Noise Denver August 2013  Søndergaard B. Low Frequency Noise from Large Wind Turbines Summary and Conclusions form Measurements and Methods. AV 140/08. DELTA April 2008  Madsen K. D. Low Frequency Noise from Large Wind Turbines Final report. AV 1272/10. DELTA November 2010  Møller H. Low Frequency Noise from Large Wind Turbines, Acoustics University of Aalborg June 2010 (in Danish)  Møller H. Low Frequency Noise from Large Wind Turbines update 2011, Acoustics University of Aalborg May 2011 (in Danish)  Møller H. Low-frequency noise from large wind turbines J. Acoust. Soc. Am. 129 (6), June 2011  Statutory order 1284 of 15. December 2011 Noise from wind turbines from the Danish ministry of the environment (in Danish)  Jakobsen J. Danish regulation of low frequency noise from wind turbines. 15th International Meeting on Low Frequency Noise and Vibration and its Control Stratford upon Avon UK 22nd 24th May 2012  Sørensen T. Experiences with the New Danish Rules for the Calculation of Low Frequency Noise from Wind Turbines 15th International Meeting on Low Frequency Noise and Vibration and its Control Stratford upon Avon UK 22nd 24th May 2012
Noise from large wind turbines (with focus on low frequencies) Christian Sejer Pedersen M.Sc. EE., Ph. D. Associate professor Acoustics, Department of Electronic Systems, Aalborg University Fredrik Bajers
Project Report EFP-6 project Low Frequency Noise from Large Wind Turbines Final Report Performed for Danish Energy Authority AV 1272/1 Project no.: A41929 Page 1 of 7 21 November 21 DELTA Venlighedsvej
Assessment of low-frequency noise due to windturbines in relation to low-frequency background noise Eugène de Beer (firstname.lastname@example.org) Peutz bv, Paletsingel 2, 2718 NT, Zoetermeer, The Netherlands. Summary
Hub North Netværksarrangement d. 14. Juni 2011 Jan Bisgaard Envision Global Innovation Centre Silkeborg, Denmark Agenda: 1. Presenting (Jan Bisgaard) 2. Company profile 3. Strategies 4. Product road map
ORIENTERING FRA MILJØSTYRELSENS Environmental noise regulation in Denmark Orientering nr. 45 JEL/PFI/ilk 17. januar 2012 This paper gives an overview of the Danish legislation in dealing with environmental
5.2 Limits for Wind Generators and Transformer Substations In cases where the noise impact at a Point of Reception is composed of combined contributions due to the Transformer Substation as well as the
Aalborg Universitet Assessment of lowfrequency noise from wind turbines in Maastricht Møller, Henrik; Pedersen, Steffen; Staunstrup, Jan Kloster; Pedersen, Christian Sejer Publication date: 2012 Document
Dansk standard DS/ISO 1999 1. udgave 2014-06-26 Akustik Metode til beregning af forventet høretab forårsaget af støj Acoustics Estimation of noise-induced hearing loss DS/ISO 1999 København DS projekt:
Investigation of sound insulation for a Supply Air Window field measurements and occupant response Lars Sommer SØNDERGAARD 1 ; Søren Vase LEGARTH 2 1 DELTA, Denmark ABSTRACT The Danish Environmental Protection
Final report 1.1 Project details Project title Capacity credit of wave and solar energy Project identification (program abbrev. and file) Name of the programme which has funded the project Energinet.dk
Nordic Master in Didactics of Mathematics NORDIMA Barbro Grevholm Seminar i Bergen den 7-8 september 2011 Nordic Master in Didactics of Mathematics Project number NMP-2009/10730 The Master Consortium consists
Name Marie Tygesen Dalsgärd Hansen ABR Denmark ApS ABR Denmark ApS Starting Date: February 2008 Report Date: 18 October 2009 General Observations Since Marie started with the ABR Program in February 2008,
COACH BOT Modular e-course with virtual coach tool support LIFELONG LEARNING PROGRAM LEONARDO da VINCI Aarhus Social and Health Care College TRAINING FOR HEALTHCARE PROFESSIONALS AND HOME CARE PROVIDERS
We help ideas meet the real world Project Report EFP-06 project Low Frequency Noise from Large Wind Turbines Summary and Conclusions on Measurements and Methods Client: Danish Energy Authority Page 1 of
OVERENSSTEMMELSESCERTIFIKAT CERTIFICATE OF COMPLIANCE Dette overensstemmelsescertifikat skal ledsages af en udstyrsfortegnelse This certificate of compliance shall be accompanied by a record of equipment
Setting Targets for Acoustic Design Kaj Dam Madsen DELTA email@example.com DANSIS Meeting at DELTA 5. October 2005 Presentation Outline Short discussion of acoustic design criteria Presentation of simple method
GUIDELINE ON BOUNDARY NOISE LIMIT FOR AIR CONDITIONING AND MECHANICAL VENTILATION SYSTEMS IN NON-INDUSTRIAL BUILDINGS 1. Scope This guideline sets out the maximum boundary noise emission limits for air
CASE STUDY National Renewable Energy Laboratory Testing Wind Turbine Power Generators using PULSE United States of America Industrial Products PULSE The National Renewable Energy Laboratory (NREL) is operated
An Introduction to Sound and Wind Turbines Mark Bastasch, PE March 2011 What is Sound? A rapid pressure fluctuation above and below the static atmospheric pressure measured in decibels (db) Typical sound
Airborne Sound Insulation with XL2-TA Sound Level Meter This application note describes the verification of the airborne sound insulation in buildings with the XL2-TA Sound Level Meter. All measurements
Student evaluation form Back Number of respondents: 17 1. Multiple choice question Percentage Name of course: [Insert name of course here!] Course Objectives: [Insert course objectives (målbeskrivelse)
Claus B. Jensen IT Auditor, CISA, CIA I am employed in Rigsrevisionen, Denmark. (Danish National Audit Office) I have worked within IT Audit since 1995, both as internal and external auditor and now in
Quality Guide CJC Quality Guide Vol. 7 April 2015 1 CJC Quality Guide An introduction to C.C.JENSEN A/S Quality Guide It is important that our customers know what C.C.JENSEN A/S stands for when talking
Sound Power measurements according to IEC 61400-11 Siemens Wind Power All Rights Reserved 2011 Sound Power measurements according to IEC 61400-11 Tomas Hansen, Lars Enggaard email: firstname.lastname@example.org Page
wind turbines in DEnmark Contents Foreword Page 3 Wind power one of the solutions to the challenges of energy policy Page 4 The challenges of energy and climate policy Energy policy objectives EU energy
Table of Contents Questionnaire #1: The Patient... 2 Questionnaire #2: The Medical Staff... 4 Questionnaire #3: The Visitors... 6 Questionnaire #4: The Non-Medical Staff... 7 Page1 Questionnaire #1: The
Acoustic Assessment Report HAF Wind Energy Project Township of West Lincoln, Ontario Prepared for: Vineland Power Inc. 222 Martindale Road St. Catharines, Ontario L2R 7A3 Prepared by: Ian R. Bonsma, PEng
This document has been downloaded from the library section of www.wind-power-program.com Visit our website for information on the WindPower program and the UK Wind Speed Database program both downloadable
Too Much Workmate 1. Work in pairs. Find these expressions in the text. Read them aloud. 1 Jo større han blev, desto mindre motionerede han. 2 I mange år havde han ikke kunnet gå i biografen. 3 Han løste
Dansk standard DS/ISO 22514-3 1. udgave 2008-05-08 Statistiske metoder i procesledelse Kapabilitet og performance Del 3: Analyse af maskinperformance for måleværdier på (diskrete) emner Statistical methods
Insurance of Intangible Asset Risks IP in innovative economy - Symposium Krakow, Poland 4-5 September 2008 Agenda Introduction to SAMIAN What do we mean by IP Risk? What insurance solutions exist for European
Application for research funding under the research programme: Research in Organic Food and Farming International Research Co-operation and Organic Integrity (DARCOF III 2005-2011) Funded by the Ministry
Dansk standard DS/EN ISO 28803 1. udgave 2012-04-23 Ergonomi Fysisk miljø Anvendelse af internationale standarder for personer med særlige behov Ergonomics of the physical environment Application of international
Dansk standard DS/ISO 18434-1 1. udgave 2012-03-26 Tilstandsovervågning og diagnosticering af maskine Termografi Del 1: Generelle procedurer Condition monitoring and diagnostics of machines Thermography
INFRASOUND UNDER CONTROL Dr.-Ing. Hani Mahmoud El Nokrashy NOKRASCHY ENGINEERING An de Masch 24, D-25488 Holm, Germany SUMMARY Infrasound emitted by some types of machines, that is sound at frequencies
V2-8 kw The turbine that goes anywhere Versatile, efficient, dependable and popular The highly efficient operation and flexible configuration of the V2 make this turbine an excellent choice for all kinds
LOW FREQUENCY NOISE AND INFRASOUND ASSOCIATED WITH WIND TURBINE GENERATOR SYSTEMS A LITERATURE REVIEW Ontario Ministry of the Environment RFP No. OSS-078696 Ontario Ministry of the Environment 2 St. Clair
entering the Turkish market. /3 The purpose of this report was to observe Vestergaard Company A/S s possibilities of Summary Vestergaard Company A/S Belinda S. Jensen, Gamze Celik, Katrine Junker og Kristine
DS-information DS/CWA 16356-1 1. udgave 2011-11-09 Vejledning til en europæisk COREfaktura-datamodel med UN/CEFACT CII-retningslinjer for implementering Del 1: Introduktion Guide for a European CORE INVOICE
DS-information DS/ISO/IEC TR 20000-4 1. udgave 2010-12-14 Informationsteknologi Serviceledelse Del 4: Procesreferencemodel Information technology Service management Part 4: Process reference model DS/ISO/IEC
Dansk standard DS/ISO 30301 1. udgave 2011-11-22 Information og dokumentation Ledelsessystem for dokumentstyring Krav Information and documentation Management systems for records Requirements DS/ISO 30301
Research on the Danish heroin assisted treatment programme Katrine Schepelern Johansen Anthropologist, PhD Post.doc, Department of Anthropology, University of Copenhagen Treatment with heroin in Denmark
Noise Design Advice Noise can be a major factor to consider in any new development. This design advice is to help those involved in development in Leeds achieve an acceptable noise environment for people
DNV SERVICE SPECIFICATION DNV-DSS-904 Type Certification of Wind Turbines JANUARY 2012 The electronic pdf version of this document found through http://www.dnv.com is the officially binding version FOREWORD
Report PSO-07 F&U project no. 7389 Noise and energy optimization of wind farms Validation of the Nord2000 propagation model for use on wind turbine noise Final Report Performed for Energinet.dk AV 1238/09
Dansk standard DS/ISO/IEC 18013-4 1. udgave 2012-01-11 Informationsteknologi Personlig identifikation ISO-overensstemmende kørekort Del 4: Prøvningsmetoder Information technology Personal identification
Paper Number 30, Proceedings of ACOUSTICS 2011 2-4 November 2011, Gold Coast, Australia Comparison of predicted and measured wind farm noise levels and implications for assessments of new wind farms Tom
Agil Business Process Management - i Finans Thomas Hildebrandt Lektor, PhD Leder af gruppen for Proces- & Systemmodeller ved IT Universitetet i København og Interessegruppen for processer og IT ved Infinit
Dansk standard DS/EN 16309+A1 2. udgave 2014-09-18 Bæredygtighed inden for byggeri og anlæg Vurdering af bygningers sociale bæredygtighed Beregningsmetoder Sustainability of construction works Assessment
Optimized thin layers for highways - Inter noise paper 2007 Danish Road Institute Report 153 2007 Ministry of Transport and Energy Road Directorate Guldalderen 12 DK-2640 Hedehusene Denmark Telephone +45
Green Micropower Bill Friends of the Earth Scotland Association for the Conservation of Energy Consultation response March 2006 Introduction Friends of the Earth Scotland (FoES) and the Association for
Rising to the Offshore Challenge Offshore Siemens Wind Power A/S, Brande, Denmark Content Siemens Wind Power A/S, Offshore Business Segment Our Performance Our Market Perspectives Common Challenges Our
Page 1 of 5 Preliminary Audible Noise Study Pittsburg 10 th Street, N-S Orientation Rev. Date Section Page Remarks Signature 0 17.11.06 all all first issue Page 2 of 5 1 Audible Noise Study 1.1 Basis The
Dansk standard DS/EN 15603 1. udgave 2008-02-20 Bygningers energieffektivitet Samlet energiforbrug og definition af energiklasser Energy performance of buildings Overall energy use and definition of energy
Aksel Gruelund Sørensen 1 1997 Offshore Action Plan Five offshore areas were pointed out Feasibility studies were made A demonstration project should be erected on each site A vision of 4,000 MW of offshore
Dansk standard DS/ISO/IEC 25062 1. udgave 2008-05-08 Softwareudvikling Kvalitetskrav til og evaluering af softwareprodukter (SQuaRE) Fælles industriformat (CIF) til brugbare testrapporter Software engineering
MORGENBOOSTER 2015 DISRUPTIVE BUSINESS DESIGN JIM KEYES, CEO, BLOCKBUSTER, 2008 NEITHER REDBOX OR NETFLIX ARE EVEN ON THE RADAR SCREEN IN TERMS OF COMPETITION 2000 HEY, VI SKAL HA ET WEBSITE HM 2009 HEY,
Dansk standard DS/ISO 10381-5 1. udgave 2005-11-09 Jordundersøgelser Prøvetagning Del 5: Vejledning i undersøgelse af jordforurening på bymæssige og industrielle grunde Soil quality Sampling Part 5: Guidance
Kvalifisering av ny teknologi Siemens AS 26.05.2011 Siemens Oil & Gas solutions - Offshore 2010. All rights reserved. De tre viktigste tingene subsea: Pålitelighet Pålitelighet Pålitelighet Hvorfor kvalifisering?
DECIBEL - Main Result Calculation: 6 x V126 x HH150 Noise calculation model: ISO 9613-2 General Wind speed: 8,0 m/s Ground attenuation: General, Ground factor: 0,4 Meteorological coefficient, C0: 0,0 db
Dansk standard DS/ISO 16038 1. udgave 2005-11-14 Kondomer Vejledning i brug af ISO 4074 ved kvalitetsstyring af latexkondomer Rubber condoms Guidance on the use of ISO 4074 in the quality management of
FÉDÉRATION EUROPÉENNE DE LA MANUTENTION Section Industrial Trucks FEM 4.003 Information of the application of the EC Regulation on the noise of forklifts 2 nd Edition August 2009 Table of contents Page
Dansk standard DS/ISO/IEC 90003 1. udgave 2004-05-10 Software udvikling Retningslinjer for anvendelse af ISO 9001:2000 til computersoftware Software engineering Guidelines for the application of ISO 9001:2000
Presentation One sensor in each luminaire - efficient lighting control 25 % savings on seamless daylight adjustment. One sensor in each luminaire - efficient lighting control 25 % savings on seamless daylight
Dansk standard DS/ISO 20022-1 1. udgave 2013-05-29 Bankvæsen Universelt meddelelsessystem for den finansielle sektor Del 1: Metamodel Financial services Universal financial industry message scheme Part
Wind turbine Excess Noise evaluation Marko Antila (email@example.com) VTT Technical Research Centre of Finland Background Wind turbine construction booming in Finland Now just below 500 MW, target 2.5
Applying New Computer-Aided Tools for Wind Farm Planning and Environmental Impact Analysis Morten Lybech Thøgersen * (firstname.lastname@example.org), Per Nielsen *, & Mads. V. Sørensen * Per Toppenberg ** & Erik Søe Christiansen
Department of Environment, Community and Local Government 20 th February 2014 Re: Response to Draft Revised Planning Guidelines Dear Sir/Madam, Element Power (EPI) welcomes the opportunity to make a submission
26/10 2015 Nordic Built Active Roofs and Facades ELLEBO RENOVATION CONCEPT & ACTIVE HOUSE EVALUATION ENVIRON MENT ENERGY WINTERGARDEN vs. SUMMERGARDEN COMFORT CONCEPT 26/10 2015 WINTER GARDEN FACADE 12
Introduction to the IEC 61400-1 standard Peter Hauge Madsen Risø DTU IEC or ISO? (Electric component, machine or building or a wind turbine) Wind turbine generator system ~ Wind turbine structure 2 The
Sound Power Level determination of AEG KM880 electrically operated food preparation appliance CHRISTER HEED AND ANDERS SÖRENSSON 4B1150 Stockholm March 2007 Marcus Wallenberg Laboratoriet för Ljud- och
Occupational Noise in the Norwegian oil industry: Cost/benefit as a result of new requirements in Norwegian Oil and Gas Recommended Guidelines for Handling Noise Tønnes A. Ognedal, Sinus AS Reidulf Klovning,
5th International Conference on Wind Turbine Noise Denver 28 30 August 2013 Environmental noise assessment of proposed wind farms using annual average L dn Mark Bliss, BKL Consultants Ltd. #308-1200 Lynn
The Current State of Responsible Investment in Denmark Dansif 2014 Study May 2014 CONTENT: EXECUTIVE SUMMARY 2 HOVEDRESULTATER 3 METHODOLOGY 4 OVERVIEW OF THE 50 LARGEST INSTITUTIONAL INVESTORS IN DENMARK