Presentation delivered at the NZEB Public Sector workshop held in the Aishling Hotel, Dublin, January 2017.

1. WORKSHOP ON THE PUBLIC SECTOR NZEB INTERIM SPECIFICATION
Niall Lowther MRIAI Department of Education & Skills
 Introduction
 NZEB Schools Research Projects
 PH Schools Research Projects

2. 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

3. 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

4. WORKSHOP ON THE PUBLIC SECTOR NZEB INTERIM SPECIFICATION 30th January 2017
Achieving Building Fabric Performance

5. WORKSHOP ON THE PUBLIC SECTOR NZEB INTERIM SPECIFICATION 30th January 2017
Achieving Building Fabric Performance

6. 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

7. 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

8. 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

9. 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

10. WORKSHOP ON THE PUBLIC SECTOR NZEB INTERIM SPECIFICATION 30th January 2017
Heat Loss through the Building Fabric
Roof Construction:

11. 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%

12. 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

13. 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

14. WORKSHOP ON THE PUBLIC SECTOR NZEB INTERIM SPECIFICATION 30th January 2017
Heat Loss through the Building Fabric
Psi Value (linear)
ψ = W/mK

15. WORKSHOP ON THE PUBLIC SECTOR NZEB INTERIM SPECIFICATION 30th January 2017
Heat Loss through the Building Fabric

16. 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.

17. WORKSHOP ON THE PUBLIC SECTOR NZEB INTERIM SPECIFICATION 30th January 2017
Heat Loss through the Building Fabric

18. WORKSHOP ON THE PUBLIC SECTOR NZEB INTERIM SPECIFICATION 30th January 2017
Heat Loss through the Building Fabric

19. 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

20. 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

21. 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