NZEB

Question 1

What is NZEB?

Answer 1

Near Zero Energy Buildings (NZEB)

NZEB is a building that has a very high energy performance. 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 renewables sources produced on site or nearby.

Question 2

How was NZEB introduced?

Answer 2

EU Energy Performance of Buildings Directive required all new residential & commercial buildings to be NZEB by the end of 2020.

All new public buildings was by the end of 2018.

Question 3

What were the changes in energy performance through the adoption of NZEB?

Answer 3

Non-Domestic:

• new builds equivalent to 60% improvement on energy performance since the 2008 Building Regs
• renewables to provide 20% of energy use
• Enhanced backstop insulation requirements
• Increased consideration for thermal bridging
• Changes in lighting specification
• Airtightness requirements
• Limiting solar gain

Domestic:
- new builds equate to 25% improvement in energy performance since 2011 Buildings Regs

Major Renovation:
- where over 25% of the surface area of the envelope undergoes renovation, building is to be brought up to a cost optimal level (B2 Rating)

Question 4

What have been the cost implications of NZEB?

Answer 4

A key factor impacting cost is the requirement for 20^ of building energy requirements to be renewable (PV Panels, Heat Pumps, etc)

As there is only a small sample size of completed buildings with NZEB implemented, it is hard to ascertain the exact increases and different building types will see varying cost increases (e.g. schools, offices, retail, dwellings, etc).

In general, NZEB can increase costs by anything from 2-2.5% on an office building to circa 8% for a school building.

However this cost increase only includes the additional capital outlay and doesn’t account for the long-term cost differences through a Life Cycle Cost analysis.

Question 5

How is compliance with NZEB monitored?

Answer 5

DEAP = Dwelling Energy Assessment Procedure

or

NEAP = Non-Residential Energy Assessment Procedure

Question 6

How are NEAP & DEAP calculated?

Answer 6

Through software that compares the performance of the actual building against a reference building.

Calculations included are:

• Primary Energy Factor (the amount of energy from/delivered energy)
• Renewable Energy Ratio (Ratio of PV, Solar, Wind, Heat Pumps on-site or nearby)

Question 7

What has been the impact of NZEB for the Design Team?

Answer 7

M&E Consultant

• Specification of HVAC
• Preparing building calculations
• more collaboration required from outset for planning
• increased focus on site inspections and construction quality

Architect

• Increased specs for building fabric and airtightness
• Mandatory calculations on thermal bridging
• more collaboration required from outset for planning
• increased focus on site inspections and construction quality

Question 8

What has been the impact of NZEB for Contractors?

Answer 8

• Emphasis on construction quality
• airtightness testing is mandatory
• ensuring buildings are commissioned correctly

Question 9

What has been the impact of NZEB for the Client?

Answer 9

- increased costs
BUT
- higher spec building
- more certainty of the quality of product
- reduced running costs

Question 10

What have been the key changes to Part L as a result of NZEB?

Answer 10

Non-Dwellings (2017)

• Energy performance 70% better than 2006 Part L
• 65% less carbon emissions
• 20% renewable energy ratios
• U-values improved – walls 0.18, External doors 1.4, floors 0.18
• 5m3 Airtightness
• Section added on minimum controls for heat pumps

Dwellings (2019)

• guidance on overheating
• air permeability backstop
• RER 20%
• Max Permitted Energy Performance Coefficient =0.30
• Max Permitted Carbon Performance Coefficient = 0.35

Question 11

Differences between NZEB and Part L?

Answer 11

TBC