Post on 08-Feb-2017
WORKSHOP ON THE PUBLIC SECTOR NZEB INTERIM SPECIFICATION
Niall Lowther MRIAI Department of Education & Skills
Introduction
NZEB Schools Research Projects
PH Schools Research Projects
WORKSHOP ON THE PUBLIC SECTOR NZEB INTERIM SPECIFICATION 30th January 2017
Energy Efficient Buildings
Maximise Solar Gains & Natural Light
Minimise Heat Losses
Integration of Highly Efficient Systems
Applying Public Sector NZEB Interim Specification
WORKSHOP ON THE PUBLIC SECTOR NZEB INTERIM SPECIFICATION 30th January 2017
Building Fabric
Thermal Performance of Building Elements
• Walls • Floors • Roof • Glazing
Thermal Bridging
Air Permeability of External Envelope
Achieving Building Fabric Performance
WORKSHOP ON THE PUBLIC SECTOR NZEB INTERIM SPECIFICATION 30th January 2017
Achieving Building Fabric Performance
WORKSHOP ON THE PUBLIC SECTOR NZEB INTERIM SPECIFICATION 30th January 2017
Achieving Building Fabric Performance
WORKSHOP ON THE PUBLIC SECTOR NZEB INTERIM SPECIFICATION 30th January 2017
Heat Loss through the Building Fabric
U-value
rate at which thermal energy is conducted through the building element
Lower u-value = better thermal performance
Units : W/m2K
WORKSHOP ON THE PUBLIC SECTOR NZEB INTERIM SPECIFICATION 30th January 2017
Heat Loss through the Building Fabric
Maximum average elemental U-values (W/m2K)
Fabric Element TGD Part L Dwellings
2011
TGD Part L Other than Dwellings
2008
DES TGD’s
Interim NZEB Specification
2017
Roofs -horizontal ceiling -slope -flat roof
0.16
0.16 0.20
0.16
0.20 0.22
0.16
0.16 0.16
0.15
0.15 0.15
Walls 0.21 0.27 0.27 0.18
Floor 0.21 0.25 0.25 0.15
Windows & Doors
1.60 2.20 1.80/1.6 1.4
WORKSHOP ON THE PUBLIC SECTOR NZEB INTERIM SPECIFICATION 30th January 2017
Heat Loss through the Building Fabric
Ground Floor:
150mm Concrete Slab
U-Value (calculated in accordance with ISO 13370)
55mm Insulation (λ=0.021 W/mK) = 0.25 W/m2K
150mm Insulation (λ=0.021 W/mK) = 0.12 W/m2K
110mm Insulation (λ=0.021 W/mK) = 0.15 W/m2K
WORKSHOP ON THE PUBLIC SECTOR NZEB INTERIM SPECIFICATION 30th January 2017
Heat Loss through the Building Fabric
External Walls: U-Value (calculated in accordance with ISO 6946)
Cavity
110mm Cavity 70mm Insulation (λ=0.020 W/mK) = 0.21 W/m2K
150mm Cavity 110mm Insulation (λ=0.020 W/mK) = 0.18 W/m2K
External Wall Insulation
230mm Insulation (λ=0.034W/mK) = 0.15 W/m2K
WORKSHOP ON THE PUBLIC SECTOR NZEB INTERIM SPECIFICATION 30th January 2017
Heat Loss through the Building Fabric
Roof Construction:
WORKSHOP ON THE PUBLIC SECTOR NZEB INTERIM SPECIFICATION 30th January 2017
Heat Loss through the Building Fabric
Windows:
NZEB Interim Specification
U-value = 1.4 W/m2K
G-Value = 40%
Light Transmittance = 71%
WORKSHOP ON THE PUBLIC SECTOR NZEB INTERIM SPECIFICATION 30th January 2017
Heat Loss through the Building Fabric
Thermal Bridging: Definition ISO 10211:2007(E) part of the building envelope where the otherwise uniform thermal resistance is significantly changed by • full or partial penetration of the building envelope by materials with a different thermal conductivity, and/or • a change in thickness of the fabric, and/or • a difference between internal and external areas, such as occur at wall/floor/ceiling junctions
WORKSHOP ON THE PUBLIC SECTOR NZEB INTERIM SPECIFICATION 30th January 2017
Heat Loss through the Building Fabric
Types of Thermal Bridging Repeating Thermal Bridges timber or steel studs; rafters; joists Geometric Thermal Bridges building form; corner of external wall; wall floor junction; eaves Constructive Thermal Bridges rsj penetrating a wall
WORKSHOP ON THE PUBLIC SECTOR NZEB INTERIM SPECIFICATION 30th January 2017
Heat Loss through the Building Fabric
Psi Value (linear) ψ = W/mK
WORKSHOP ON THE PUBLIC SECTOR NZEB INTERIM SPECIFICATION 30th January 2017
Heat Loss through the Building Fabric
WORKSHOP ON THE PUBLIC SECTOR NZEB INTERIM SPECIFICATION 30th January 2017
Heat Loss through the Building Fabric
TGD Part L 2008
To avoid excessive heat losses and local condensation problems, provision should be made to limit local thermal bridging, e.g. around windows, doors and other wall openings, at junctions between elements and at other locations.
Any thermal bridge should not pose a risk of surface or interstitial condensation and any excessive increase in heat loss associated with the thermal bridge should be taken account of in the calculation of average U-value.
WORKSHOP ON THE PUBLIC SECTOR NZEB INTERIM SPECIFICATION 30th January 2017
Heat Loss through the Building Fabric
WORKSHOP ON THE PUBLIC SECTOR NZEB INTERIM SPECIFICATION 30th January 2017
Heat Loss through the Building Fabric
WORKSHOP ON THE PUBLIC SECTOR NZEB INTERIM SPECIFICATION 30th January 2017
Heat Loss through the Building Fabric
Air Tightness :
Reduces Heat Loss through Convection
Reduces passage of moisture into the building fabric
Air Permeability (m3/(m2h) Gross internal area less than 250 m2
5
Air Permeability (m3/(m2h) Gross internal area greater than 250 m2
3
WORKSHOP ON THE PUBLIC SECTOR NZEB INTERIM SPECIFICATION 30th January 2017
Heat Loss through the Building Fabric
Air Tightness :
• “Red Line” Boundary
• Site Supervision
• Airtight “Champion”
• Testing
WORKSHOP ON THE PUBLIC SECTOR NZEB INTERIM SPECIFICATION 30th January 2017
Heat Loss through the Building Fabric
Conclusion:
• Achievable
• Implications for funding agents
• Improved build quality & comfort for occupants
• Building typology
• Implications for designers
• Contractor standard of workmanship
• Building users