NNI article: The Noise Impact of Future Sustainable Homes in Ireland
By Dr. John Kennedy, john.kennedy@tcd.ie, and Ella Keogh keoghel@tcd.ie, Trinity College Dublin
Introduction
Noise mitigation is a key environmental challenge that faces sustainable development. New approaches in energy production and distribution will change urban acoustic landscapes. The current carbon and global warming crises highlight the need to provide sustainable housing that utilises renewable energy technologies. Residential areas will be affected by noise produced in sustainable homes which will include small scale energy production. Noise pollution has a negative effect on human health and so it is crucial that the noise impact of potential sustainable energy technologies going into future homes is evaluated.
According to the European Environment Agency, over 13 million adults are estimated to suffer sleep disturbances from environmental noise in Europe. (1) Member states of the European Union have an obligation to assess noise levels on strategic noise maps and report where threshold values of 55 dB for Lden and 50 dB for Lnight have been surpassed. These threshold values represent a physical scale to describe environmental noise at values that are linked to the harmful effects of noise. (2)(3)
Irish homes use 7% more energy than the EU average and emit approximately 60% more 𝐶𝑂2 than the average EU home. This is because the floor area of the average Irish dwelling is amongst the largest in the EU, due to Ireland’s low share of apartments. (4) In 2018, Irish buildings were 70% reliant on fossil fuels. The Irish Climate Action Plan 2021 states that the government will reduce greenhouse gas emissions by 51% by 2030 and by 2050 they will phase out all fossil fuels in the building sector in order to reach net zero targets. Electricity is the sector with the largest proposed emissions reductions by 2030. (5) Therefore, sustainable renewable energy technologies are the only option to provide energy to a future home in Ireland. There are different energy needs in a home – heat for comfort and for domestic hot water and electricity for plug-ins such as white goods, lighting and for devices. The Irish Climate Action Bill 2021 commits to installing 600,000 heat pumps in residential buildings by 2030 as one of the steps to meet the required level of emissions reduction.
In this research, the noise footprint is calculated for a future home including a heat pump for heat and domestic hot water, and photovoltaic panels and residential wind turbines to supply electricity and reduce demand on the national grid. The aim is to understand the noise effects of different scenarios of these small-scale renewable energy technologies installed in future sustainable homes.
Methodology
Future Home Model
Passivhaus is a popular building standard that the construction industry are considering for future home construction. It was first developed is Germany and focuses on the concept that houses should be built to use less energy. The standard is acclaimed for being energy efficient, environmentally friendly as well as comfortable and affordable – all key aspects that a model of a future home must consider. (6) There are five core concepts of the Passive House build: (1) Air-tight construction, (2) thermal insulation, (3) heat recovery ventilation, (4) high-performance windows, and (5) thermal bridge-free detailing. (7) There are a number of Passive House certified homes already built in Ireland.
Standard
Calculations were made according to ISO 9613, a standard that deals with the acoustic attenuation of sound during propagation outdoors. iNoise is commercial implementation of the calculation methods set out in ISO 9613 and was used to model the equivalent continuous A-weighted sound pressure levels predicted with different installations of renewable energy technologies.
Sound Power Levels
Heat pumps and wind turbines were modelled in iNoise to investigate the noise effects of these technologies on the surrounding residential areas.
The heat pump investigated in the models is the Daikin Altherma ERQ. It is a monobloc outdoor unit with a COP of 3.94. (8) Sound pressure levels were determined from technical datasheets and these were then converted to A-weighted sound power levels for iNoise.
where Lw is the sound power level, SPLA is the A-weighted sound pressure level, r is the distance from the source to the receiver and D is a correction factor referring to the number of reflecting planes.
Two different scales of wind turbine were modelled. A small wind turbine, with output 5kW and a micro wind turbine with output 0.6kW, were both used in different scenarios. (8) Sound pressure levels were determined from a previous publication and converted to sound power levels.
where Lw is the sound power level, Lp is the sound pressure level, Q is the directivity of the source which correlates to a +3 dB increase for ground reflection and r is the distance from the source to the receiver.
Table 1: Sound power levels for the renewable energy technologies modeled
Results
Multiple scenarios were investigated to assess the noise footprint for different combinations of the renewable energy technologies. A middle house in a row of seven terraced houses with semi-detached houses on each side were chosen as the focus for the simulation. Receivers were placed at the centre house (R2), and at both end of terrace houses (R1, R3) to investigate the noise at different bedroom locations in the row of houses, see Table 2. The building layout was chosen as representative of suburban housing developments in Ireland. The building heights were 6m, which is representative of a two-storey house in Ireland. (9)
It is estimated by the Sustainable Energy Authority of Ireland (SEAI) that 61% of all energy used in a household is for space heating, 20% for hot water heating, 16% for lighting and appliances and 2% for cooking, based on BER estimates. In 2021, the average Irish home used 20,424 kWh of energy (weather corrected). (10) This correlates to approximately 55.96 kWh per day. From these figures an approximation of the average energy provision to a home of the scenarios was created and an estimate of the reduction of grid reliance determined. The results of these estimations are included in Table 3.
The Daikin Altherma ERQ heat pump has a COP of 3.94. This means that although it provides 81% of the energy requirements of the home, approximately 45.3 kWh, it used 11.5 kWh per day.
The micro wind turbine is an Ampair A600, which provides 1300 kWh of energy annually for a 5m/s wind speed. This correlates to approximately 3.56 kWh per day. (11)
The small wind turbine is an Evance Iskra R9000 which provides 9018 kWh of energy annually for a 5 m/s wind speed. This correlates to approximately 24.7 kWh. (12)
According to the SEAI, an at home solar photovoltaic system of approximately 20m^2 generates around 2600 kWh of electricity annually. This correlates to approximately 7.1 kW per day. Planning permission is required where these panels cover more than 50% of the area of the roof of the home. In these scenarios it was estimated that each house had 10m2 of solar photovoltaic panels approximating to 3.55 kWh per day.
Heat Pump
The first scenario modelled was the impact of heat pumps alone on the houses. Reflections from the surrounding buildings produced the highest noise level not in the centre of the row of houses but at one end. Lden for this scenario was calculated to be 43.1 dB at R1, 32.9 dB at R2 and 45 dB at R3.
Micro Wind Turbine
The micro wind turbines were simulated alone. One could be placed in each garden as the rotor diameter of the micro wind turbine was 1.7m. To avoid interference from other wind turbines, they must be placed five times the rotor diameter apart. Lden for this scenario was calculated to be 63.3 dB at R1, 51 dB at R2 and 62.4 dB at R3.
Small Wind Turbine
The small wind turbines have a rotor diameter of 5.4m, which means they must be at least 27m apart. They are not suitable for installation at each house on the terrace because of this. Lden for this scenario was calculated to be 65.3 dB at R1, 56.1 dB at R2 and 73.1 dB at R3.
Scenario 1
The combination of micro wind turbines and heat pumps were investigated together. The heat pumps were located close to the houses and the wind turbines located further from the houses. Each home was modelled with a heat pump and micro wind turbine. Lden for this scenario was calculated to be 63.3 dB at R1, 51.1 dB at R2 and 62.4 dB at R3.
Scenario 2
The combination of small wind turbines and heat pumps were investigated together. Each home was modelled with a heat pump and small wind turbine was shared between five homes. Lden for this scenario was calculated to be 56.7 dB at R1, 54.9 dB at R2 and 56.8 dB at R3.
The noise levels at each receiver location is shown in Table 2. A comparison of estimations of energy savings is calculated in Table 3.
Table 2: Noise levels calculated at receiver locations
Table 3: Estimation of reduction of energy per home in Scenario 1 and 2
Conclusions
Lden ranged from 51.1 dB to 63.3 across both scenario models. Table 2 shows that Scenario 1 had the most variation in noise at the receivers. Across all models R2, the receiver at the house at the centre of the terrace row, calculated the lowest value of the three receivers. In Table 3, Scenario 2 reported lower noise levels than Scenario 2 and reduced the reliance of the houses on the grid by a 3% more than Scenario 1. Community energy resources may be more efficient than individual resources.
The European Noise Directive requires European Union member states to report where threshold values of Lden = 55 dB have been exceeded. Irish Building Regulations Part E requires that the sound insulation in walls be a minimum of dB. The adverse human health impacts of noise and these threshold values must be considered when installing renewable energy technologies in residential areas.
There is a wide range of potential scenarios including a variety of residential small-scale energy production technologies. Many technical data sheets for heat pumps and wind turbines do not include full spectra sound pressure levels which are required to map these technologies according to ISO 9613. It was difficult to find a selection of sources which had this information and so the choices for technologies were limited. Manufacturers should be required to provide full spectra sound pressure levels so that the noise impact of these technologies can be properly assessed for suitability before installation.
References
1. European Environment Agency. Environmental Noise. 2019.
2. European Environment Agency. Managing exposure to noise in Europe. 2021.
3. European Commission. Directive 2002/49/EC. Environmental Noise Directive. 2002.
4. Sustainable Energy Authority Of Ireland. Energy in the Residential Sector [Internet]. 2018. Available from: https://www.seai.ie/data-and-insights/seai-statistics/key-publications/energy-in-residential-sector/
5. Irish Department of the Environment, Climate and Communications. Climate Action Plan 2021. Department of the Taoiseach, 2021.
6. Williams F. Passivhaus: the future of architecture? [Internet]. RMJM. 2022. Available from: https://rmjm.com/passivhaus-the-future/
7. International Passive House Association. Passive House Brochure. 2018.
8. Taylor J, Eastwick C, Lawrence C, Wilson R. Noise levels and noise perception from small and micro wind turbines. Renewable Energy. 2013 Jul 1;55:120-7.
9. Dublin City Council. 16.7.2 Height Limits and Areas for Low-Rise, MidRise and Taller Development* (See Building Height in Dublin). 2020. Available from: https://www.dublincity.ie/dublin-city-development-plan-2016-2022/16-development-standards/167-building-height-sustainable-city/1672-height-limits-and-areas-low-rise-midrise
10. Sustainable Energy Authority Of Ireland. Irelands’s Energy Statistics Residential [Internet]. 2021. Available from: https://www.seai.ie/data-and-insights/seai-statistics/key-statistics/residential/
11. Ampair 600 230V Wind Turbine Brochure | Manualzz [Internet]. manualzz.com. [cited 2023 Mar 20]. Available from: https://manualzz.com/doc/11532935/ampair-600-230v-wind-turbine-brochure
12. Evance R9000 Wind Turbine [Internet]. Eco Evolution Blog. 2009 [cited 2023 Mar 9]. Available from: http://ecoevolution.ie/blog/evance-iskra-r9000/
