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Scott Tallon Walker - nZEB Design Discussion Talk Dec 2017

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To successfully deliver nZEB projects, a low-energy design approach will need to be introduced to every stage of the design and construction process.

The intent of this presentation is to provide a light overview of the new nZEB requirements from an architectural perspective. The outcome is for participants to leave the presentation with a good understanding of the key legislative and design/ technical requirements (building energy usage, thermal bridge and mould free detailing, renewable requirements, etc) without overloading participants with ‘techno-babble’.

The presentation material focuses on established design principles; important aspects of the Ireland's Non-Domestic Part L 2017; completed nZEB projects; practical information on building services; and ‘areas to watch’ during the construction process.

Published in: Design
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Scott Tallon Walker - nZEB Design Discussion Talk Dec 2017

  1. 1. Scott Tallon Walker Architects nZEB The New Minimum Standard “We cannot Solve our problems with the same thinking we used when we created them.” - Albert Einstein Noel Hughes| 15th December 2017
  2. 2. Legislation • Introduction • EPBD • Part L - UK • Part L - Ireland • Part L - Renovation • Cost nZEB Typology • Domestic • Apartment • Office • Education • Sport Hall • Retail nZEB Design Principles • Form + Design • Structural Types • Solar • Ventilation • Construction nZEB Tips + Tricks • Design Advice • Resources Advice • Management Advice • Services Advice • Design Risks • Management Risks • Construction Risks Scott Tallon Walker Architects nZEB | Chapters Noel Hughes| 15th December 2017
  3. 3. Scott Tallon Walker Architects nZEB | Introduction nZEB Definition [EPBD (2010/31/EU) Article 2] ‘Nearly Zero-energy Building’ means a building that has a very high energy performance, as determined in accordance with Annex I [of the EPBD]. The nearly zero or very low amount of energy required should be covered to a very significant extent by energy from renewable sources, including energy from renewable sources produced on- site or nearby; Noel Hughes| 15th December 2017
  4. 4. Scott Tallon Walker Architects nZEB | EPBD Energy Performance of Buildings Directive (EPBD) The objective of the Directive is to set a framework for the application of minimum requirements for the energy performance of new buildings across the EU. • Member states to ensure that all new buildings are “Nearly Zero Energy Buildings” by 31st Dec 2020 • Member states to ensure that all new buildings owned and occupied by Public Authorities are `Nearly Zero Energy Buildings’ after 31st Dec 2018 • Major Renovations to be at Cost Optimal Level in Building Codes Noel Hughes| 15th December 2017
  5. 5. Scott Tallon Walker Architects nZEB | EPBD EPBD Public Deadline European Energy Performance of Buildings Directive (2010/31/EU) Article 09 states: • all new buildings which are owned or occupied by Public Authorities need to be nZEB the 31st December 2018 Note: “Occupied” is the keyword, as it implies that a premises must have a valid nZEB Certificate of Completion by 31/12/2018 for a public tenant to occupy a new premises without being in violation of the EPBD and face fines Allowing for the 21 day validation period the last day for submitting a non-nZEB compliant Certificate of Completion is the 7/12/2017 Noel Hughes| 15th December 2017
  6. 6. Scott Tallon Walker Architects nZEB | EPBD EPBD + Renovation Works European Energy Performance of Buildings Directive (2010/31/EU) Article 02 states: • the total cost of the renovation relating to the building envelope or the technical building systems is higher than 25 % of the value of the building, excluding the value of the land upon which the building is situated; or • more than 25 % of the surface of the building envelope undergoes renovation; Noel Hughes| 15th December 2017
  7. 7. Scott Tallon Walker Architects nZEB | Part L National Implementation European Energy Performance of Buildings Directive (2010/31/EU) Article 4 states: • Member States shall take the necessary measures to ensure that minimum energy performance requirements for buildings or building units are set with a view to achieving cost-optimal levels. In Ireland and the UK, this is the Part L energy building regulation. Ireland UK Noel Hughes| 15th December 2017
  8. 8. Scott Tallon Walker Architects nZEB | Part L UK and nZEB The future requirements for nZEB remain unclear in the UK. The UK government is not expecting to announce if the current regulations will change before spring 2018. Scotland, Wales and NI Scotland and Wales have committed to meeting the nZEB standard and to updating their building energy standards as necessary. However, progress does not appear to be rapid enough to deliver compliance by the 2019 EU deadline No information is available on Northern Ireland’s progress to nZEB. However, it is reasonable to assume it is in line with the other devolved regions Noel Hughes| 15th December 2017
  9. 9. Scott Tallon Walker Architects nZEB | Part L London and nZEB The Getting to Zero report, by the London Energy Transition Initiative (LETI) urged the Greater London Authority (GLA) to make a clear commitment to the ‘building fabric first’ approach to energy performance, for both heating and cooling. The report also recommends that the current “zero carbon” targets should be updated to be more closely compliant with the nZEB target by adopting international building performance standards. • Total energy requirements should be in kWh/m²/yr, replacing the current CO₂ emission methodology • Also challenges the current London Plan regarding carbon saving. Namely gas CHP Noel Hughes| 15th December 2017
  10. 10. Scott Tallon Walker Architects nZEB | Part L TGD Part L - Non Domestic (2017) To be applied 1st January 2019 • Provides an improvement in performance in the order of 60% over TGD Part L (2008) • Improved Fabric Specification • Advanced Services and Lighting specification • Renewable Energy Ratio of 20% TGD Part L - Dwellings (2018) • Public Consultation Early 2018 • Application 2019 (subject to regulatory process) Noel Hughes| 15th December 2017
  11. 11. Scott Tallon Walker Architects nZEB | Part L TGD Part L - Non Domestic (2017) • Renewables requirement will be included as Renewable Energy Ratio (RER) = 20% • Represents a very significant level of energy provision from renewable energy technologies Regulation L5 (b) • “Where the MPEPC of 1.0 and MPCPC of 1.15 is achieved an RER of 0.20” • “Where the MPEPC of 0.9 and MPCPC of 1.04 is achieved an RER of 0.10” • Renewable energy sources include Photovoltaic, Heat Pumps (Air source and ground source), Biomass, Solar Thermal ,Primary Energy Savings from Combined Heat and Power (CHP), Renewable district heating Noel Hughes| 15th December 2017
  12. 12. Scott Tallon Walker Architects nZEB | Part L Reference Building Values Current Conservation of Fuel and Energy - Dwellings 2011 Current Conservation of Fuel and Energy – Non- Dwellings 2008 New Conservation of Fuel and Energy – Non- Dwellings 2017 Improvement Opening Areas Offices and Shops - Windows and Pedestrian Doors are 40% of the total area of Exposed Walls Offices and Shops - Windows and Pedestrian Doors are 40% of the total area of Exposed Walls U- Values: Walls 0.21 W/m²K 0.27 W/m²K 0.18 W/m²K 33% U- Values: Roof 0.16 W/m²K 0.16 W/m²K 0.15 W/m²K 6% U- Values: Floor 0.21 W/m²K 0.25 W/m²K 0.15 W/m²K 40% U- Values: Windows DEAP Table 6a 2.20 W/m²K 1.40 W/m²K 36% Glazing Solar Transmittance DEAP Table 6a 0.72 0.40 Thermal Bridging Default = 0.15 W/m2K ACD = 0.08 W/m2K Add 16% to fabric heat loss Y-Value = Actual Length of Key Junctions x Advanced psi value Air Permeability 5 m³/(hr.m²) Floor Area 10 m³/(hr.m²) 5 m³/(hr.m²) Floor Area ≤250m² 3 m³/(hr.m²) Floor Area ≥250m² 30% 70% Renewable Energy Ratio 10 kWh/m²/yr to heating or 4 kWh/m²/yr to electrical None 20% Proposed Performance requirements for Part L nZEB Buildings - Reference Building Fabric Noel Hughes| 15th December 2017
  13. 13. Scott Tallon Walker Architects nZEB | Part L Building Type Primary Energy CO₂ emissions Building Energy Rating Energy Improvement CO₂ Improvement kWh/yr/m² kg/yr/m² Indicator BER % % Office (Natural Ventilation) 2F 62.8 12.6 0.3 A2 65 65 Office (Air Conditioned) 2F 100.1 20.7 0.5 A3 66 67 Office (Natural Ventilation) 4F 60.1 12.1 0.3 A2 63 64 Office (Air Conditioned) 4Fl 98.6 20.5 0.5 A3 65 66 Hotel (Air Conditioned) 348.1 65.3 0.5 B1 66 67 Retail (Air Conditioned) 178.3 38.2 0.4 A3 68 67 Mixed Use 89.3 18.2 0.3 A2 69 60 School 57.6 11.2 0.4 A3 50 51 Proposed Energy and Carbon Dioxide emissions performance for Part L nZEB Buildings Noel Hughes| 15th December 2017
  14. 14. Scott Tallon Walker Architects nZEB | Part L Par 2.3.4 The following improvements are normally considered to be cost optimal and will typically be economically feasible when more than 25% of the surface area of a building is being upgraded • Upgrading heating systems more than 15 years old • Upgrading cooling and ventilation systems more than 15 years old • Upgrading general lighting systems that have an average lamp efficacy of less than 40 lamp lumens per circuit-watt and that serves greater than 100m² TGD Part L (2017) - Major Renovations Par 2.3.2 When calculating the proportion of surface area undergoing renovation the area of the whole building external envelope should be taken into account including i.e. external walls, roofs, floors, windows, doors, and roof windows and lights Works to the surface area of the building include the following: • Cladding the external surface of the element • Drylining the internal surface of an element • Replacing windows • Stripping down the element to expose the basic structural components and then rebuilding to achieve all the necessary performance requirements. Building Type Primary Energy BER kWh/yr/m² Air Conditioned Retail 338 E1 Natural Ventilated Offices and Other Buildings 124 B3 Air Conditioned Office 180 C3 Air Conditioned Hotel 342 E2 Schools 60 B1 Other Air Conditioned Buildings 338 E2 Other Naturally Ventilated Buildings 124 B3 Major Renovation - Cost Optimal Level Noel Hughes| 15th December 2017
  15. 15. Scott Tallon Walker Architects nZEB | Part L • Par 1.5.5: Commissioning The key elements of a commissioning plan, identifying the systems that need to be tested and the tests that will be carried out and should be developed at the design stage • Par 1.5.4.2: Airtightness Testing Air pressure testing should be carried on all development sites to show attainment of backstop value of 5 m³/(hr.m²). The tests should be carried out by a person certified by an independent third party • Par 1.5.6.1: Ductwork Leakage Leakage testing should be carried out on systems served by fans with a design flow greater than 1m³/s Other Part L (2017) Requirements • Lighting should meet minimum recommended standards for efficacy and controls • Par 1.3.6: Overheating Assessment The designer should specify what the indoor comfort specification and perform an overheating assessment to ensure overheating is avoided BMS • Boilers over 100kW to have BMS controls and AC systems over 200m² to have BMS controls • A full BMS system will provide full zoned time control and weather compensation where applicable, frost protection or night set-back optimization and monitoring and targeting Noel Hughes| 15th December 2017
  16. 16. Scott Tallon Walker Architects nZEB | Part L Cost Impact Independently access construction costs give this increase at: • Office 2% – 2.4% • Air Conditioned Hotels 4.6% – 5.4% • Air Conditioned Retail 2.4% – 3% • Natural Ventilated Mixed Use 1.3% – 1.5% Noel Hughes| 15th December 2017
  17. 17. Scott Tallon Walker Architects nZEB | Typology Key Question What will an nZEB look like? Vandermaelen Development, Brussels Noel Hughes| 15th December 2017
  18. 18. Scott Tallon Walker Architects nZEB | Domestic Example Silken Park Location: Citywest, Co. Dublin Completion: April 2018 BER: A2 (47-49.6 kWh/m²/yr) Passive House Certified Developer: Durkan Residential Architect: BBA Architecture Building type: •Phase 3 of a private development, consisting of a mix of terrace, semi- detached and detached houses. •Twenty-four 2-bed terraced/ semi- detached houses (84m²), •Twenty-nine 3-bed terraced/semi- detached houses (109m²), •Five 4-bed semi-detached houses (120m²) •One 4-bed detached (126m²) •All 59 houses will come pre-wired for EV charge points •Roofs are designed to take the weight of a solar PV system covering the whole roof Noel Hughes| 15th December 2017
  19. 19. Scott Tallon Walker Architects nZEB | Apartment Example Roebuck Student Residences Location: UCD Size: 3097m2 Completion: 2010 BER: A3 Heat Demand: 12kWh/m²/yr Primary Energy: 114kWh/m²/yr PH Certified Architect: Kavanagh Tuite Architects Building Info: • 6 storeys high, housing 300 students • Residence style accommodation with en- suite student rooms, kitchenette and living on either side of a spine corridor • External walls formed in structural concrete, cast with permanent magnetizes formwork requiring decoration finish only Roof: 0.150 W/(m2K) Walls: 0.170 W/(m²K) Floor: 0.150 W/(m2K) Glazing: 0.800 W/(m2K) Curtain Wall: 1.200 W/(m2K) Air Permeability: 0.600 ACH Noel Hughes| 15th December 2017
  20. 20. Scott Tallon Walker Architects nZEB | Office Example Enexis Regional Office Location: Maastricht, Netherlands Size: 5912 m2 Completion: 2013 Cost: €6,715,500 Primary Energy: 34.7kWh/m²/y Architect: Kent Pedersen Architects Building Info: • BREEAM excellent • First Energy-Neutral design certificate in the Netherlands • The building has energy-efficient lighting, daylight control, presence detection • PV cells on the roof Climate Control: Demand Controlled Solar Water Heater: 13.3m² PV: 1406m² Cooling: Free Cooling Ventilation: Balanced Noel Hughes| 15th December 2017
  21. 21. Scott Tallon Walker Architects nZEB | Office Example GouweZone Location: Gouda, South Holland Size: 2747 m2 Completion: 2012 Primary Energy: 18.3kWh/m²/y % of Renewables: 74% Architect: EGM Architects Building Info: • A energy-neutral office development • Completely CO2 neutral and uses 70% less energy than typical office buildings • All electric • Tenants offered a multi-year contract with a fixed all-in price in terms of energy costs. Heating: Electric Heat Pump Delivery: Underfloor Heating and Concrete Core Activation PV: 620m² Cooling: Free Ventilation: Balanced Noel Hughes| 15th December 2017
  22. 22. Scott Tallon Walker Architects nZEB | Education Example CREST Centre for Renewable Energy & Sustainable Technologies Location: Enniskillen Size: 455 m2 Completion: 2014 Heat Demand: 13kWh/m²/yr Primary Energy: 66kWh/m²/yr PH Certified Architect: Paul McAlister, The Barn Studio Building Info: •Large areas of glazing to the south assist with solar gain and allows natural light to penetrate deep into the floor plan • Reduces the amount of artificial light required to the exhibition spaces. •Utilises air to water heat pump, with underfloor distribution Roof: 0.160 W/(m2K) Walls: 0.121 W/(m²K) Floor: 0.086 W/(m2K) Glazing: 0.750 W/(m2K) Air Permeability: 0.600 ACH Noel Hughes| 15th December 2017
  23. 23. Scott Tallon Walker Architects nZEB | Education Example Plein Oost School Location: Haarlem, Noord-Holland Size: 2521 m2 Completion: 2014 Primary Energy: 32.7kWh/m²/y % of Renewables: 92% Architect: Kristinsson Building info: • The school is energy-neutral • Building houses two schools with outdoor space and gym, a playgroup and an after-school care centre • Solar panels are installed with an east- west orientation at an angle of 10 degrees • The school board signed an agreement with the municipality to finance the extra investment , this is earned back through lower energy and maintenance costs PV: 672m² Cooling: Heat Pump 27 MJ /m² Ventilation:Balanced Noel Hughes| 15th December 2017
  24. 24. Scott Tallon Walker Architects nZEB | Education Example Centre for Medicine Location: University of Leicester Size: 9863 m2 Completion: 2014 Cost: £42,000,000 Heat Demand: 15kWh/m²/yr Primary Energy: 116kWh/m²/yr PH Certified Architect: Associated Architects Building Info: • BREEAM Excellent • Reduced annual energy bills by 80%. • Heating from local district heating • Minor cooling from pipes in slabs • Hot water from local electric heaters, successfully avoided distribution losses • Largest green wall in the UK outside of London Roof: 0.122 W/(m2K) Walls: 0.187 W/(m²K) Floor: 0.398 W/(m2K) Glazing: 0.580 W/(m2K) Air Permeability: 0.300 ACH Noel Hughes| 15th December 2017
  25. 25. Scott Tallon Walker Architects nZEB | Sport Hall Example Södra Climate Arena Location: Växjö, Sweden Size: 3589 m2 Completion: 2012 Heat Demand: 11kWh/m²/yr Primary Energy: 118kWh/m²/yr PH Certified Architect: Kent Pedersen Architects Building Info: • Tennis hall with four tennis courts, a cafe, conference rooms, a gym, changing rooms and technical facilities • The hall is heated by air, the rest of the rooms have radiators • The entire system is demand-controlled Roof: 0.068 W/(m2K) Walls: 0.107 W/(m²K) Floor: 0.125 W/(m2K) Glazing: 0.940 W/(m2K) Air Permeability: 0.130 ACH Noel Hughes| 15th December 2017
  26. 26. Scott Tallon Walker Architects nZEB | Retail Example Tesco Location: Tramore, Waterford Size: 3970 m2 Completion: 2008 Heat Demand: 15kWh/m²/yr Primary Energy: 758 kWh/m²/yr PH Certified Architect: Joseph Doyle Architects Building Info: •First certified Passive House supermarket in the world •Waste heat of refrigeration plant connected with ventilation system • Uses 45% less energy than a supermarket of a similar size saving 420 tonnes of carbon dioxide per annum Roof: 0.15 W/(m2K) Walls: 0.18 W/(m²K) Floor: 3.68 W/(m2K) Perimeter insulation only - Ground below building acts as a heat storage Glazing: 1.08 W/(m2K) Air Permeability: 0.31 ACH Noel Hughes| 15th December 2017
  27. 27. Scott Tallon Walker Architects nZEB | Retail Example Quirke’s Pharmacy Location: Clonmel, Tipperary Size: 229m2 Completion: 2014 BER: A2 (46.75 kWh/m²/yr) Heat Demand: 12 kWh/m²/yr Primary Energy: 150 kWh/m²/yr PH Certified Architect: PassivHaus Architecture Building info: •Combined pharmacy at the ground level and an apartment above •Third non-residential passive house building in Ireland •Original building was over 200 years old, and in poor condition before renovation •Came in on budget, and opened a month ahead of schedule Roof: 0.097 W/(m2K) Walls: 0.124 W/(m²K) Floor: 0.140 W/(m2K) Glazing: 0.085 W/(m2K) Air Permeability: 0.600 ACH Noel Hughes| 15th December 2017
  28. 28. Scott Tallon Walker Architects nZEB | Databases Noel Hughes| 15th December 2017 Passive House Project Database http://www.passivhausprojekte.de Netherlands Enterprise Agency Energy Efficient Construction Database https://www.rvo.nl/initiatieven/overzicht/27008
  29. 29. Scott Tallon Walker Architects nZEB | Design Principles Design is not just what it looks like and feel like. Design is how it works. - Steve Jobs These are principles are just ‘Rule of Thumb’ But if you know how the rule works and why it is there – they you know what to do if want to design something different Noel Hughes| 15th December 2017
  30. 30. Scott Tallon Walker Architects nZEB | Form + Design Orientation Basics: Sun rises in the East and sets in the West Obvious as it may seem, it is important to remember that during winter the sun actually rises south of east and in the summer rises north of east. So in the summer north facing facades will very briefly be exposes to the sun. It is important to consider the suns path when design areas which may develop micro-climates: sunken or sheltered area, sun rooms + gardens and atrium spaces. It is also important to consider the potential impacts of glare from the low winter sun when developing BREEAM and LEED projects. Noel Hughes| 15th December 2017
  31. 31. Scott Tallon Walker Architects nZEB | Form + Design Form Optimisation Basics: Compact building use less energy The greater the surface areas of a building envelope, the more energy it will lose through the fabric, thermal bridges and air permeability. A sphere has the smallest surface area by volume (form factor) of any form. In the winter a single storey home could use up to 25% more energy compare to a two storey home of the same floor area The best form is a slightly elongated solar- orientated form that provides a balance between solar heat gains and heat losses Noel Hughes| 15th December 2017
  32. 32. Scott Tallon Walker Architects nZEB | Form + Design Thermal Comfort Every person has a different opinion on what is a comfortable internal temperature, typical a temperature range of 18-22˚C with a humidity of 40-60% is comfortable for a human being. Building services typical aim to provide an internal environment of: • 20˚C @ 50% RH Any internal temperature of over 25˚C is considered to be overheating. Note: TGD Part L does not have a requirement to address overheating in a building. However, Passive House requires the number of hours in a year that exceeds 25°C to be limited to 10% annually. Noel Hughes| 15th December 2017 + Keeping cool what should be kept cool + Keeping warm what should be kept warm + Without energy consumption = Comfortable Environment
  33. 33. Scott Tallon Walker Architects nZEB | Form + Design Rationalise the Layout Basics: Cold Rooms to the North, Warm Rooms to the South – use buffer zones It is wise to plan a building such that rooms that require little to no heating or are only occupied occasionally (toilets, store room, bedrooms etc) are located on the northern face with ‘active’ room to the southern face. This rule is based on the ‘servant and served’ principle of space planning. Noel Hughes| 15th December 2017
  34. 34. Scott Tallon Walker Architects nZEB | Form + Design Fabric First A phrase that will become more prevalent thanks to nZEB. ‘Fabric First’ is the principle that the majority of a building heat is lost and gained through its fabric. Insulation is a barrier to heat flow both inward and outwards of a structure and is required to maintain an appropriate level of thermal comfort. Basics: The basic rule is to wrap the buildings external envelope continuously (including under the floor slab) with 200 - 300mm of insulation Significant amounts of energy is lost due to the infiltration of external air, mostly through poor quality construction junctions which are not airtight. Insulation is the cheapest and most effective way to save energy. Insulation first, then Renewables Noel Hughes| 15th December 2017
  35. 35. Scott Tallon Walker Architects nZEB | Structural Types Thermal Mass High thermal mass building elements will absorb heat slowly and store it. The store heat will then be released slowly into the building In buildings with high thermal mass, the highest indoor temperatures will occur in the early hours of the morning, typically a number of hours after the highest outdoor temperatures have been reached. This slow response time is known as the ‘Thermal Flywheel Effect’ Note: In a highly insulated building with a stable internal temperature the benefits of thermal mass can be limited. Without internal temperature fluctuation, the stabilising effect of thermal mass is irrelevant. Noel Hughes| 15th December 2017
  36. 36. Scott Tallon Walker Architects nZEB | Structural Types Lightweight Structures Lightweight structures with a low thermal mass are better suited to building with an intermittent use, which needs to be heated quickly or are less sensitive to thermal comfort requirements. These buildings need to be well insulated and benefit from a quick response heating systems. Heavyweight Structures Heavyweight structure favour building which is in constant use as internal temperature swings are naturally dampened and the heat gains are retained. It is important to plan for the time lag between the maximum internal and external temperatures to prevent potential overheating in the summer or valuable heat energy being flushed away by the ventilation system or night cooling Noel Hughes| 15th December 2017
  37. 37. Scott Tallon Walker Architects nZEB | Solar Solar Shading As designers, there are a range of solutions for solar shading and prevent unwanted solar gains External shading devices perform better than internal methods as they completely prevent the sun’s rays from entering the building. Internal blinds, while preventing solar glare, will not prevent overheating Basics: Southern solar shading should be horizontal due to the high angle of the summer sun. East or West shading should be vertical to shade against the low angle of the sun. Sothern Shading East/ West Shading Noel Hughes| 15th December 2017
  38. 38. Scott Tallon Walker Architects nZEB | Ventilation Natural Ventilation There are two main forces that underpin natural ventilation systems, they are Wind and thermal Buoyancy. In Ireland and the UK, the external wind conditions is the most dominating deciding factor in the daily levels of natural ventilation for most buildings. Wind meeting a building creates a pressure difference between its windward and leeward faces, and this drives ventilation Note: As most natural ventilation are wind or external air pressure drive, on still days they will either operate at a greatly reduce performance or be completely ineffectual. Noel Hughes| 15th December 2017
  39. 39. Scott Tallon Walker Architects nZEB | Ventilation Single-Sided Ventilation For spaces that have only access to a single external façade, a maximum of 6m can be effectively ventilated. Allow for an opening area of at least 5% of the floor area to be ventilated. Cross Ventilation Cross ventilation relies on the pressure difference between the windward and leeward facades. It is effective for spaces who’s depth is no greater then 5 times the ope height. Again allow for an opening area of at least 5% of the floor area to be ventilated. Stack Ventilation Stack Ventilation relies on buoyancy of air and requires a temperature difference of over 2 ˚C to be inside and outside. • Rule-of-Thumb: In Ireland/UK, all year around natural ground floor ventilation will need a five-storey high stack Noel Hughes| 15th December 2017 Single –Sided Ventilation Stack Ventilation Cross Ventilation
  40. 40. Scott Tallon Walker Architects nZEB | Ventilation Mechanical Heat Recovery Through the use of a mechanical ventilation system with a heat recovery unit (MVHR), it is possible to extract heat from the exhaust air and use it to warm incoming fresh air. Such systems need a well-insulated building with an airtight building envelope Note: Unless a building achieve an airtightness of a minimum of 3 Air Changes per Hour – MVHR will not be cost effective At higher ACH rates an MVHR unit will use more energy in run its air pump that any energy recovery from the exhaust air Noel Hughes| 15th December 2017
  41. 41. Scott Tallon Walker Architects nZEB | Ventilation Night Time Purging Thanks to the high energy performance in nZEB. And combined with an increase in airtightness levels (1.0 ACH should be achievable, the minimum Passive House requirement is 0.6 ACH) will potentially increase the risk of overheating. A cost-effective mean of cooling a building is night purging. This can either be mechanical or natural ventilation system and can be a smart system controlled by a BMS or a simple as an opening windows at night. It is a highly efficient, simple and cheap method of cooling a structure and reducing the risk of overheating No Night Time Purging Night Time Purging Noel Hughes| 15th December 2017
  42. 42. Scott Tallon Walker Architects nZEB | Construction Thermal Bridges Thermal bridging occurs in building envelopes where there are gaps or breaks in the insulation envelope creating pathways for heat loss. Thermal bridging also occurs in building envelopes when materials with higher thermal conductivity (such as steel, timber and concrete) are used. These materials, if not properly detailed, will create pathways for heat to bypass the thermal insulation. Types of Thermal Bridges: • Linear Thermal Bridges • Repeating Thermal Bridges • Non-Repeating Thermal Bridges • Geometrical Thermal Bridges Heat always looks for the path of least resistance Noel Hughes| 15th December 2017
  43. 43. Scott Tallon Walker Architects nZEB | Construction Airtightness It is vital to reduce air infiltration in a structure. The additional costs of air tightness measures is negligible but are entirely reliant on build quality. TGD Part L Non-Domestic 2017 requires a minimum of airtightness of 3 ACH. If a design team wishes to achieve a higher rated building performance and the 10% renewable target – A high airtightness value will be required. Note: The graph shows the annual heat gains and losses of two version of a domestic dwelling, with the only difference being airtightness. The first house has a 5 Air change per hour and the second has the minimum Passive House requirement of 0.6 ACH. The result is an energy saving of 40% thanks to a reduction in heat losses. 32.6 7 5 4.9 14.2 14.2 4 3.2 8.2 8.1 7.4 7.4 11.4 7.7 34.6 13.7 22.4 18.3 25.8 20.4 0 10 20 30 40 50 60 70 80 90 5.0 ACH Losses 5.0 ACH Gains 0.6 ACH Losses 0.6ACH Gains Comparing Airtightness Ventilation Thermal Bridge Windows Floor Roof External Walls Non-useful Heat Gains Heat Demand Internal Heat Gains Solar Heat Gains Noel Hughes| 15th December 2017
  44. 44. Scott Tallon Walker Architects nZEB | Tips + Tricks It is always cheaper to do the job right the first time - Phil Crosby Some basic thing to watch out for on a nZEB project Noel Hughes| 15th December 2017
  45. 45. Scott Tallon Walker Architects nZEB | Design Advice Keep it Simple Building occupants will ignore or override complex controls and systems. And over time they will forget how to effectively operate a system, typical ruining and energy saving or adding to ‘wear and tear’. People feel more comfortable when they have control over their environment. So any design must be robust, intuitive and simple. Noel Hughes| 15th December 2017
  46. 46. Scott Tallon Walker Architects nZEB | Design Advice Reduce Energy demand through Design The building sector accounts for about 40% of total energy consumption and 38% of the CO2 emissions in the US and about 27% of the emissions in the UK are attributed to the buildings Strategies to reduce energy consumption are highly dependant on building type and a clients requirements. This means that the Architects is best placed to reduce the initial building energy requirements through clever space planning and an understanding of how building services/ systems will be used Review the ASHRAE Advanced Energy Design Guides for further information Noel Hughes| 15th December 2017
  47. 47. Scott Tallon Walker Architects nZEB | Design Advice Minimising Thermal Bridging The need for structural integrity, and the need to allow light and access into a building leads inevitably to the use of different materials with different thermal properties. Good design of each of these details to minimise the thermal loss is crucial both to keep heating demand down and to avoid cold spots where condensation might form. Have as must of the structure as possible inside the thermal envelope No penetrations means no Thermal Bridges Noel Hughes| 15th December 2017 Retrofit Window Details 1. Solid Block Wal – No Insulation 2. External Insulation to Wall + Large Thermal Bridge through existing Concrete Sill 3. External Insulation to Wall, which Window within the Insulation Layer
  48. 48. Scott Tallon Walker Architects nZEB | Resources Advice Develop a Library of Standardised Thermally Modelled Details TGD Part L – Non Domestic (2017) will require all key junction detail to be Thermally Modelled by an accredited accessor The NSAI, have established a national register of Thermal Modellers (there are currently on 14 in the country). The typical cost of to model a detail is €200-300 for a 2D thermal model and €300-400 for a 3D thermal model. With a 2-3 day turnaround time for each detail. It is prudent to develop an internal library of accredited standard details to minimise cost and time delays Noel Hughes| 15th December 2017
  49. 49. Scott Tallon Walker Architects nZEB | Management Advice Real Collaboration Due to the added complexity of achieving the nZEB energy standard, a collaboration between the construction team is essential. Full buy-in from the design team is required. Primary and secondary structures are the principal causes of thermal bridging and the oversizing of mechanical service is a major source of additional cost. Most important the main and sub- contractors need to be fully aware of the requirements and the additional pressure they put on on-site quality control. nZEB cannot be delivered with a ‘business as usual’ attitude Noel Hughes| 15th December 2017
  50. 50. Scott Tallon Walker Architects nZEB | Management Advice Fixed Design at Construction The TGD Part L – Non-Domestic (2017) requirements for thermal modelling of all details in addition to the complications of NEAP software and the Renewables requirements. This will result in any change to the building strategy during construction being onerous and potentially costly. For example, if a Contractor changes the specified wall insulation material with a similar product with a different U-value and thermal bridging properties (y-factor). Then a new thermal model will have to be produced and the building energy requirements reassessed. There is considerable risk related to undeveloped details or service strategies being issued for tender. The old motto remains true: If you haven’t drawn it - You haven’t thought about it Noel Hughes| 15th December 2017
  51. 51. Scott Tallon Walker Architects nZEB | Services Advice Simplify Services If a technology drive approach is taken to meet nZEB requirements, it is estimated that it could add 20-30% to the construction cost. The principles behind a ‘Fabric First’ approach is to minimise the need for M+E services through good design and a high- performance building fabric. Further savings can be made if service routes are thought of early in the design process. Plant spaces should be centralised to facilitate the shortest and most efficient route runs. Plants requirements should be established early in the design to ensure that they are not oversized as this will add unnecessary cost and increase the buildings energy usage Noel Hughes| 15th December 2017
  52. 52. Scott Tallon Walker Architects nZEB | Services Advice Minimising HVAC Usage Air condition systems consume a significant amount of energy and design consideration must give address any overheating risks. Offices will be most at risk of overheating. But with an appropriate use of solar shading and building strategies such as night cooling. HVAC can be greatly reduced or phased out entirely. Noel Hughes| 15th December 2017
  53. 53. Scott Tallon Walker Architects nZEB | Services Advice Appropriate Renewables In an urban location, most nZEB will mostly like rely on electric based Renewables, such as PV panels and Heat Pumps (typical ‘air to water’ or ‘air to air’) Micro Wind is typical not cost effective in Ireland and extremely rarely in an urban location Note: Micro Wind turbines are designed to operate at a wind speed of 10-12 m/s. Average Irish wind speed at 10m above ground is 4-6m/s (less in urban environments). The performance of wind turbines at these speeds drops significantly Biofuels maybe be cost-effective for rural development, but is dependant on the space available for the storage of fuels The Future is Electric Noel Hughes| 15th December 2017
  54. 54. Scott Tallon Walker Architects nZEB | Design Risks Overheating With the increase in U-value requirements and airtightness under TGD Part L - Non- Domestic (2017), the potential for overheating will increase. There are a number of definitions for overheating; CIBSE defines it as: ‘internal temperature of 28˚C is surpassed for over 1% of the time’ and Passive House as: ‘25˚C is surpassed for over 1% of the time’. It is recognised that an internal temperature of above 35˚C will create a significant danger of heat stress. The Irish TGD does not define overheating but the designer should specify what the indoor comfort they wish to achieve and perform an overheating assessment. However, any overheating risk can be reduced or eliminated through the appropriate design decisions Noel Hughes| 15th December 2017
  55. 55. Scott Tallon Walker Architects nZEB | Design Risks Mould Growth The mould grows over a wide range of temperatures, but favours temperatures similar to those inside building and wall build-ups. Thanks to the warmer internal environments created by the TGD Part L - Non-Domestic (2017) standard, mould will thrive if moisture movement across build- ups is not properly considered. Irish building regulation has a minimum requirement for surface temperature (fRSI), the requirement of which have to be covered by the designer's professional indemnity insurance. The surface temperature factor is established by dividing the measured surface temperature by the difference in temperature between the inside and outside air (20˚C as per ISO standards). See adjacent table for TGD Part L - Non- Domestic (2017) fRSI requirements. Noel Hughes| 15th December 2017
  56. 56. Scott Tallon Walker Architects nZEB | Design Risks Setout of Services In order to meet the new TGD Part L - Non-Domestic (2017), all primary service distribution routes will need to be insulated, as well as many secondary services. For example, the heat gains in a large building from uninsulated domestic hot water can be substantial, particularly during summer months and contribute to overheating. If a ø32mm pipe needs 25mm insulation, the resulting ø82mm pipe may increase the width requirements of service zones and studwork The setout of pop-up positions to floor slab and penetrations to external walls will all need to take account of the requirements for additional insulation Noel Hughes| 15th December 2017
  57. 57. Scott Tallon Walker Architects nZEB | Management Risks Tender + Fear Factor A substantial upskilling of onsite contractor is required in order to meet the nZEB standards. While there are a number of programmes nationally aim at this, they have not seen widespread adoption by the construction industry. The need to educate key onsite member will inevitably effect tender prices and construction programmes. There is also the prospect of contractors applying a ‘fear factor’ sum - overpricing works which they are unsure or unfamiliar with. When drawing up tender documentation, clarity must be provided on • The high level of construction quality • The additional level of inspections (recommended multiply airtightness test to ensure a consistent performance) • Any additional foreman responsibilities • All damages or bonuses associated with meeting key requirements Noel Hughes| 15th December 2017
  58. 58. Scott Tallon Walker Architects nZEB | Management Risks Buying Design Risks The majority of cost-saving measures regarding the implementation of nZEB are made at both the initial design and design development stages of the project programme. Combined with the TGD Part L - Non- Domestic (2017) implementation date of early 2019, presents a potential risk when bidding for projects at Construction stage only. There will be significant manhours and cost in upgrading a substantively completed design to the new TGD Part L - Non- Domestic (2017) standards. Noel Hughes| 15th December 2017
  59. 59. Scott Tallon Walker Architects nZEB | Construction Risks On-Site Quality Control The importance of commitment from on- site contractors to the nZEB process cannot be understated. Contractors who have successfully completed low-energy projects have recommended the used of continuous onsite inspect and the appointment of an onsite champion. Areas of concern would be: • Airtightness • Continuity of Insulation • Integrity of vapour control layers Suitable clause will need to any contract to ensure onsite construction quality (with appropriate awards and damages) and key dates for inspection will need to be included in the construction programme Be prepared for “I have been building for XX years” arguments Noel Hughes| 15th December 2017
  60. 60. Scott Tallon Walker ArchitectsNoel Hughes| 15th December 2017 Good Luck You’ll be fine

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