Good afternoon, my name is Evelyn Moran. Welcome to my presentation on my flat top block retrofit project. The particular aspect of my design I would like to discuss today is sustainability. I will begin with a brief overview of my design. Following this I will run through all of the sustainable aspect of my design including, site, carbon emissions and energy use, sustainable community, health and wellbeing, materials, u values, LTBs, carbon emissions, condensation risk, Existing embodied carbon and systems. Finally I will discuss the BREEAM metric and the rating this project achieved.
The key design decision I made were to:-Add an extra floor and corner block, this has resulted in an increase in apartment numbers from 38 units to 54 units. Higher density is a sustainable option for this city centre location. - Existing balconies and access decks have been taken inside a new fabric to eliminate thermal bridges and increase the area of units. New access deck and balcony structure is independent of existing building to eliminate thermal bridging. As much of the fabric as possible has been retained, existing walls have been clad with external wall insulation and render. Majority of new walls are prefabricated timber panels. Sustainable, low embodied energy materials have been chosen in this scheme. The design process began with DEAP, ensuring the required reductions were achieved. Revit was used for modelling and for embodied carbon calculations. Build desk u and therm were used for u value calculations and condensation risk analysis and finally Therm was used to calculate LTBs.
The sustainable aspects of the site include:Adding New trees and sedum roof which will attract migrating birds and other wildlife. The sedum roof and increased soft landscaping will also reduce rain water run off. 40 bicycle spaces provided in a secure shed, although it is less than one per apartment it should be sufficient considering adjacent transport links and the city bike scheme. 43 Kingspan Thermomax evacuated tube solar panels are proposed. These will sit on the roof at 15 degree angle facing due south. According to DEAP analysis these panels will provide between 30% and 63% of the apartments heat requirements (excluding CHP at 30%)
Area weighted average of BER. Existing Average BER: E1Proposed Average BER: A2Existing average primary energy: 18172 kWh/yProposed average primary energy: 2920 kWh/y84% REDUCTIONExisting average carbon emissions: 3402 kg/yProposed average carbon emissions: 503 kg/y86% REDUCTION
The first step in creating a sustainable community would be consultation. In addition to this a community space has been provided on the ground floor, this could be a creche or gathering space and would be beneficial to the community. The site has been enclosed to make it a private area for residents only, the effect of this will be that the residents will have a sense of ownership in the space. Communal gardens, playground, foyers will provide gathering spaces for people to meet their neighbours and hopefully form lasting bonds with them. The garden will also allow residents to take ownership of them and create a sense of pride. A good mix of apartments has been provided, which will result in a good age range which is ideal for a sustainable community.
Tenant health and wellbeing is very important and will make the management of this block easier for DCC. The advantages of this scheme for health and wellbeing include: returning most of the tenants to their previous locations, which will be less disruptive;increasing apartment, storage and balcony areas;Making all units accessible;Providing gardens and play areas;Creating warm, airtight units and eliminating fuel poverty;Minimising VOCsMaximising daylighting and positioning living space to south where possible. Eliminating the threat to health that mould poses, I will talk about this in more detail later.
Initially insulation was chosen based on performance alone, however once embodied energy was taken into account wood fibre insulation was chosen due to its embodied energy content of 20mj/kg for boards and 10mj/kg for loose insulation. Majority of insulation will be FSC approved wood fibre insulation on prefabricated timber panels. Final choice of NBT Diffutherm insulation and Baumatic render was based on its BBA Certification. Kingspan ground insulation has a green guide rating of A+.
U Values were calculated in Build Desk U. U values for the walls ranged from .16 for the existing cavity walls to .23 for the new timber prefabricated panels. The reason for this variation is the change from existing wall to timber panel at different floors, in order to keep a level facade the amount of external wall insulation had to be changed. Ground slab u value was calculated in Therm, it has a U Value of .1. Roof U values are .11.
Therm was used to calculate the Y factor of two ground floor units and two mid floor units. In total 15 therm models were drawn. The average Y Factor of the ground units was .053. The average Y factor of the mid units was .057. Part L Psi values were used to calculate the Y factor of two top floor units, the average Y factor is .103, which shows that Part L psi values are too conservative to use on deep retrofit projects and it is worth taking the time to calculate them in Therm or similar package.
Build Desk U calculates any risk of interstitial or surface condensation, which could result in mould growth. All of my wall and roof build ups have no issues with condensation. A major cause of condensation and mould growth is linear thermal bridging. Therm provides a minimum surface temperature Tsi, which can be used to calculate a temperature factor (Frsi), this figure must be greater than or equal to a critical temperature factor FCRsi of 0.75. My lowest temperature factor is .91, at the junction of the ground floor and existing gable wall. So there will be no issues with mould in the retrofit.
As much of the fabric as possible has been retained, existing walls have been clad with external wall insulation and render. Existing cavities have been pumped with loose wood fibre insulation. Using Revit we can calculate that the embodied carbon in the existing concrete and brick is in the region of 319767kgCO2/kg. Demolition embodied carbon for the concrete and brick is 118402kgCO2/kg, so 63% of the existing structure/ fabric is being retained.
There will be a group heating scheme located in the plant room in the new basement. Solar panels will pre heat the water in large accumulator tanks. The main boiler will be a CHP gas boiler with 87% efficiency. An additional gas boiler with 95.5% efficiency will provide backup heating at peak times. Each unit will have a heat exchangers, control valves and meter.On demand ventilation is proposed for the units. The units will be made air tight with Intello membranes and takes at junctions. Inlets at the windows draw fresh air into the rooms when humidity is high, this is extracted from the kitchens, utilities and bathrooms when required through a fan hidden in the ceiling of the hall.
The sustainability metric applied to this project was BREEAM DOMESTIC REFURBISHMENTThe BREEAM metric was appropriate for this scheme in some areas, most notably energy as it is such a deep retrofit and energy accounts for 45% of the credits. The metric was relatively easy to complete, although some areas are not relevant to the Irish context, which results in a certain amount of guess work and ultimately results which are not completely accurate. This is due to lack of good practice, guidance documents and legislation in Ireland. If these areas were in place the metric would be highly suitable for this project, client and country. A total of 93 out of a possible 126 credits were attained resulting in a 78% score, which gives a BREEAM rating of excellent.
That's a brief overview of the sustainable aspects of my design. As I hope you can see most areas of the decision making and design were influenced by sustainability. Whether it be retaining as much of the existing structure as possible or creating a sustainable community or reducing the carbon emissions. Although my BREEAM rating of excellent may not be completely accurate it does give a good indication of the sustainability credentials of this project. Thank you very much for listening and if you have any questions I would be happy to answer them now.
Flat Top Block Presentation 18.05.13
DESIGN OVERVIEW• Maximise Site• Existing balconies and access decks• New access deck and balcony structure• Retain as much of the fabric as possible• Use sustainable materials
SITE• Maximise site• Sedum roof• Planting• Bike store• Solar Panels
CARBON EMISSIONS & ENERGY USEEXISTING BER PROPOSED BERA2E1
SUSTAINABLE COMMUNITY• Community Space• Enclosed site• Communal garden• Play ground• Apartment mix
HEALTH & WELLBEING• Tenants retain location• Apartment size increased• Balcony size increased• Part M compliance• Communal gardens/playground• Fuel poverty• VOC• Daylighting• Minimise LTB, Eliminatemould