5.6.2 SHADOW / DAYLIGHT ASSESSMENT

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1 ENVIRONMENTAL IMPACT STATEMENT SHADOW / DAYLIGHT ASSESSMENT Introduction As part of the Environmental Impact Study (EIS) required for the planning submission for the proposed 120 bed wing at the National Rehabilitation Hospital, Rochestown Ave, Co. Dublin, Ethos Engineering have undertaken a Solar Overshadowing and daylight analysis study. The purpose of this analysis is to determine if the proposed extension, which consists of 4 storeys, would increase the effects of shading / overshadowing on existing buildings, particularly where residents would be affected, on the opposite side of Rochestown Avenue. These areas of interest are shown in red in figure 1.1. The report also examines the daylight factors for a number of sample bedrooms in the new development. Figure 1.1 (Aerial View from Google Maps) We have used the IES <Virtual Environment> simulation software version 2014 to build a model of the proposed extension, including the adjacent existing buildings, which enabled us to run our Suncast analysis. This Simulation Report represents the simulation procedure, describes the methodology employed, details the model established, and explains the simulation strategy and results for the proposed extension. The shadow analysis was performed for 3 design days of the year, which included shadows cast during high summer sun, low winter sun and at the equinoxes by the STEPHEN LITTLE & ASSOCIATES OCTOBER

2 existing buildings, by the proposed extension to the National Rehabilitation Hospital, and by the surrounding residences. The images generated for this report show the following different axonometric views; Existing buildings (as per figure 1.1 above). Proposed NRH extension & Existing Buildings. This report shows only the directional properties of the shadows cast by the sun and should not be used as reference for the intensity of the sunlight for any given time. It should be noted that it is important the information conveyed in this report is reviewed carefully, as it represents Ethos Engineering s current understanding of the buildings to be analysed, and as such will form the basis of any further simulation analysis, unless changes are made in light of client review Legislation & Standards Currently, as we understand it, there are no standards or guidance documents (statutory or otherwise) on the subject of sunlight access to buildings or open spaces which have been published in Ireland. In the absence of guidance on this subject suitable for Irish climatic conditions, Ethos Engineering have referred to the relevant British Standards BS :2008: Lighting for buildings Part 2: Code of practice for daylighting as this is the generally accepted standard used by Irish practitioners. We also considered BRE s 2011 revision of the 1991 publication Site layout planning for daylight and sunlight: a guide to good practice by Paul J Littlefair. It should be pointed out that the following statement is made on the first page of this document: The advice given here is not mandatory and this document should not be seen as an instrument of planning policy. Therefore, we believe that the BRE report should be used as a secondary guide to the British Standard Receiving Environment The site of the proposed 120 bed hospital development occupies the south eastern half of the current National Rehabilitation Hospital site on Rochestown Avenue, Dun Laoghaire and is bounded by Rochestown Avenue to the north and east and by Pottery road to the south and west. There is a significant slope on the site with a fall or up to 12 meters from Rochestown Avenue (+54m) to Pottery Road (+42m). The north western half of the site is occupied by the current National Rehabilitation Hospital which consists of buildings of varying heights up to four storeys. Beyond this there is an open green area with Enterprise Rent-a-car just outside the site boundary. There is also a single storey one off house located along the Rochestown avenue side of this green area which has mature planting / trees surrounding it. The Amgen complex is located directly south of the proposed development with a large associated car park to the south east all of which is accessed from Pottery road. To the north of the application site on the opposite side of Rochestown avenue, development is typically of a residential nature consisting of 2 storey detached and semi

3 detached houses and includes the Sefton housing estate. Coming further south east along this road is located Rochestown Motors, a small single storey garage and a small development of 3no. detached residential bungalow houses at Woodpark located at the junction of Rochestown Avenue and Sallynoggin road. Just beyond this junction is the Somerton residential estate which include a mix of detached and semi-detached houses including the 18 th century Somerton House and Lodge. The Met Eireann statistics indicate that the sunniest months in Ireland are May and June. During December, Dublin receives an average of 1.7 hours of sunlight out of a potential 7.4 hours sunlight each day (i.e. only 23% of potential sunlight hours). This can be compared with the average of 6.4 hours of sunlight out of a potential 16.7 hours each day received by Dublin during June (38% of potential sunlight hours). Therefore, the impact of overshadowing will generally be more noticeable during the summer months than during the winter months. The shadow environment in urban and suburban areas is generally dense though out winter due to the low angle of the sun in mid-winter. The people who might be affected by the new development at the NRH site are the people residing in properties located closest to the site boundaries. The sensitive locations in this regard are the detached houses located in the Sefton housing estate located immediately north of the proposed development and also the detached houses along Rochestown Avenue adjacent to the Sefton housing estate and to a lesser extent the Somerton enclave just south of the junction between Rochestown Avenue and Sallynoggin road. The current number of residences currently located in sensitive areas includes approximately seventy eight detached and semi-detached houses Characteristics of the Proposal The redevelopment of the National Rehabilitation Hospital will be phased development of a new 235 bed hospital. The first element of works will be the enabling works followed by the construction of the new sports hall and pool area. This will allow the existing sports facility to be removed prior to the construction of the new 120 bed hospital. The total area of the proposed development is circa 17,900m 2 including a Sports / Hydrotherapy area of 2,385m 2. The building is arranged around two courtyards over four levels with a height to the parapet of 17.7m and 21.9m to ridge of plant room which is set back 1.3m from the parapet. The main ward building is approximately 46m from the site boundary with the hydrotherapy area slightly closer to the boundary at 27m. However, this area will essentially be underground as it takes advantage of the sloping nature of the site. The summary below references the architects Site Strategy Report. Phase 1 provides 120 beds in total and is generally located as follows: Level 03: 2no. 20 bed spinal care SCSC (A+B) wards with shared services between wards; Level 02: 2no. 15 bed Acquired Brain Injury ABI (C+D) wards with shared services between wards;

4 Level 01: 1no. 12 bed Polar Ward and 1 no. 20 bed Acquired Brain Injury ABI (B) Ward each with integrated therapies and provision for shared services between wards. Level 00: 1 no. 8 bed Paediatric Unit and 1 no. 10 bed Acquired Brain Injury ABI (A) Ward, each with integrated therapies. In summary, this phase will facilitate the relocation of all the existing beds to the new development and for the existing hospital services to be maintained throughout with a minimum of disruption to same Methodology The Solar Suncast Analysis methodology consisted of the follow distinct tasks: A. Project drawings were provided by O'Connell Mahon Architects in AutoCAD format. These included plans and elevations of the existing Buildings and Provisional Plans and Sections of proposed development. B. Computer models of the existing and proposed buildings were then developed in the Virtual Environment software based upon the geometrical details supplied by the Client. The 3D computer models were constructed at the orientation and levels as outlined in the drawings submitted to us. C. Using the Virtual Environment Suncast module an accurate shadow casting analysis was produced. This program replicates the azimuth and altitude of the sun for any specified time and date of the year, orientation, site latitude and site longitude at any given location. Suncast can be used for a variety of studies however it is essential at the planning stage to visualize the effect of proposed developments on surrounding buildings. D. Images were produced capturing the shadows cast by the proposed development at hourly intervals on the Solstice and Equinox dates of the year. In assessing the impacts on sunlight, Ethos Engineering has considered the following guidance documents: Guidelines on the Information to be Contained in Environmental Impact Statements prepared by the Environmental Protection Agency (2002) EU Directive 2011/92/EU on the assessment of the effects of certain public and private projects on the environment. The list of definitions given below is taken from Section 5: Glossary of Impacts contained in the Guidelines on the Information to be contained in Environmental Impact Statements prepared by the Environmental Protection Agency. We have also commented on our interpretation of these definitions and their implications. Definition of Impacts on Sunlight Access Imperceptible Impact: An impact capable of measurement but without noticeable consequences. The definition implies that the development would cause a change in the sunlight received at a location, capable of measurement, but not noticeable. If the development caused no change in sunlight access, there could be no impact

5 Slight Impact: An impact which causes noticeable changes in the character of the environment without affecting its sensitivities. For this definition to apply, the amount of sunlight received at a location would be changed by shadows cast by the development to an extent that is both capable of measurement and is noticeable to a minor degree. However, the shadow environment of the surrounding environment should remain largely unchanged. Moderate Impact: An impact that alters the character of the environment in a manner that is consistent with emerging trends. In this case, a development must bring about a change in the shadow environment of the area; and this change must be consistent with a pattern of change that is already taking place. This impact would occur where other developments were bringing about changes in sunlight access in the area. Significant Impact: An impact which, by its character, magnitude, duration or intensity alters a sensitive aspect of the environment. This impact would occur where the development overshadows a location to the effect that there is a significant change in the amount of direct sunlight received at that location Suncast Analysis Times and Dates The shadow casting analysis is divided into three sections; Spring Equinox (similar results to Autumn Equinox) Summer Solstice and Winter Solstice. For each section images were produced at hourly intervals as follows; Spring Equinox 07:00 19:00 (See Appendix A for Images) Summer Solstice 07:00 19:00 (See Appendix B for Images) Winter Solstice 07:00 19:00 (See Appendix C for Images) Dates used are as follows; Spring Equinox 21st March Summer Solstice 21st June Winter Solstice 21st December Details of the shadow analysis are contained in the Appendix Potential Impact Construction Phase The potential impacts of the proposed development on sunlight access are likely to be similar or lesser than the potential impacts experienced during the operation phase. Operational Phase The buildings on the NRH site, including the existing hospital facilities, will cast shadows westward towards Pottery road in the morning, onto Rochestown Avenue in the middle of the day, and towards the residential areas across the Rochestown Avenue in the late

6 afternoon. Any increase in the height of the new development will have a negligible effect as the shadow cast will generally be cast across the existing NRH site. The westward shadows cast in the morning towards Pottery road will have an imperceptible impact as the shadow never extends outside the site boundary. The shadow cast by the new development in the late afternoon is deemed to have slight impact as it extends eastwards towards the residential development at the junction of Rochestown Avenue and Sallynoggin road including the Somerton enclave just to the south east of this junction. Do Nothing Scenario In a Do Nothing Scenario, the shadow environment will remain as-is due to the existing hospital. As has been demonstrated by the shadow images in the Appendix, there are a small number of residences which will have shadows cast on them by the new development which would not have been shaded here to fore. However, these shadows are cast late in the afternoon during autumn and winter when the potential for sunlight is less than in the summer Amelioration, Mitigation Measures The new development is of a similar form to the existing hospital and is set back a significant distance from Rochestown Avenue and the sensitive locations on the opposite side of this road. This helps to reduce the length of time during the year when shadows are cast on these residences. Because of this, the method of improving daylight and sunlight has already been implemented for this proposed development. The small number of instances where shadows have been cast during the late afternoon on some more residences than here to fore but these are deemed to be permissible in this circumstance when consideration is given to the urban nature of the site and the relationship which the proposed development has with the existing hospital Predicted Impact of the Proposed Development Construction Phase The predicted impacts of the proposed development on sunlight access are likely to be similar or lesser than the potential impacts experienced during the operation phase. No further mitigation measures are deemed necessary in this case. Operational Phase Since no mitigation measures are deemed necessary for this development, the predicted impact of the proposal is equivalent to the potential impact of the proposal outlined in the previous sections. Do Nothing Scenario The impacts considered above represent a worse case scenario Model Image

7 Figure 10.1 Aerial View Extension Shown in Red, Existing shown in Blue and residential houses shown in Pink Assessment of Daylight Access within the Proposed Development The IES Virtual Environment simulation software version 2014 was used in conjunction with guidance contained in British Standard 8206 Part 2: Light for Buildings Code of Practice for Daylighting to calculate the Average Daylight Factors (ADF). The module used within this software was Radiance. Radiance is a module available in the Virtual Environment for performing daylighting analysis calculations Site Data The site data attached to the model contains values for latitude, longitude, standard meridian and orientation. Dublin was used as the location in all the daylighting simulations required for this study. Working Plane Settings and Area of Interest Defined The working plane height used was 0.85 meters above finished floor level and a margin of 0.5m away from walls and other obstructions was excluded from the calculation results as per CIBSE recommendations this is the area of interest. This helps to avoid the inclusion of potentially misleading illuminance data close to walls and windows, as illustrated in image below

8 Sky Conditions The sky conditions used in this simulation study was an unobstructed CIE standard overcast sky. The CIE Overcast Sky is used to give the worst case scenario (in design terms) for illuminance and therefore is the most suitable design sky for Daylight Factor simulations. Reflectance s The following material reflectance s have been assigned to the simulation model. Ground Floor Reflectance 23.7% Wall Reflectance 76.6% Ceiling Reflectance 85.5% Glazing Specification The following glazing specification has been assigned to the simulation model. Glazing Light Transmittance 60% Results of Daylight Assessment The results of the daylight study shows that the daylight levels in the three sample rooms of the development are above the minimum standards set out in the British Standard. The average daylight factors for the sample rooms are as follows as shown in Appendix D; Sample Room Orientation Average Daylight Factor Southwest Bedroom 2.24 Southeast Bedroom 2.37 Northwest Bedroom 2.5 The British standard states it is considered good practice to ensure that rooms in dwellings and in most other buildings have a predominantly daylit appearance. In order to achieve this the average daylight factor should be at least 2%