Ed will outline the challenges faced by those responsible for refurbishments of buildings from the perspective of a mechanical engineer and building physics nerd. The session will cover the sometimes-competing requirements of air quality, acoustics, thermal comfort, and energy efficiency and what you can do balance them. He will touch on ventilation strategies, source control, and current trends in façade design. He will examine industry trends which have drawn attention to air quality indoors, including the pandemic and the government response, and his experience of the methods being proposed to deal with air quality indoors.

1. Existing building stock: Key
refurbishments strategies for
ventilating existing buildings
Ed Wealend
Head of Research & Innovation
Cundall
CIBSE Air Quality Group

2. Who are you?
• Chartered Engineer (CEng MCIBSE)
• Chair of CIBSE AQWG
• 15 years' experience mainly in Building
Physics & Mechanical Design
• London, Hong Kong, and Shanghai
• Professional interests include:
• Air quality (TAPAS, FUVN, others)
• Building physics
• Operational Energy
• Digital engineering
• Data-analytics & machine learning.
• Biotech in the built environment.
• Director of a funicular railway

3. CIBSE AQWG
Be an advocate of
improvements in
regulatory
environment
Be a source of
best practice
guidance on
methods
Build links with
key stakeholders
Share the science
of air quality and
its impact on
people
Be a source of
best-practice
guidance on
equipment

4. What does good indoor air
quality look like?

5. What does good indoor air quality look like?
• Minimal harmful pollutants (NOx, PMs, Ozone, VOCs etc.)
• Reasonable CO2 levels
• 1000ppm OK
• 800ppm better
• 600ppm even better (if demand controlled or naturally ventilated)
• Good humidity control

6. Challenges with
refurburbishment

7. Challenges specific to refurbishments of buildings

8. Challenges specific to refurbishments of buildings
• Poor thermal performance
• Air tightness
• Insulation and thermal bridges

9. Challenges specific to refurbishments of buildings
• Existing systems
• Any ventilation?
• Natural ventilation
• Legacy plant

10. Challenges specific to refurbishments of buildings
• Existing environment

11. Industry Trends

12. Industry trends – More air please…
Approved Document F Volume 2 - consultation version - January 2021

13. Industry trends – and use less energy while you’re at it
LETI Climate Emergency Design Guide

14. Opportunities

16. Strategies

17. Steps to good indoor air quality – Roadmap
Determine air
quality
Select low
emitting plant
Determine
ventilation
strategy
Consider air
tightness
Consider
insulation &
thermal bridges
Locate intakes &
exhausts
Select filters?
Provide
adequate ‘fresh’
air for occupants
Consider
demand control
ventilation
Isolate polluting
activities
Spec low or zero
VOC materials
Educate
contractors
Enforce spec
during
construction
Pre-occupancy
air flush?
Monitor in use
RIBA Stage 6 RIBA Stage 7
RIBA Stage 1-2 RIBA Stage 2
RIBA Stage 3 RIBA Stage 4
RIBA Stage 5

18. Monitor inside and out
• Gives you a baseline
• Identify existing building performance issues
• Leaky façade
• Insufficient filtration
• Insufficient ventilation
• Excess ventilation
• Identify pandemic risk from poorly performing systems (e.g. high
CO2 levels)

19. Engage with the design team!
• They probably aren’t thinking that much about air quality
• Encourage good behaviour
• Eliminate fossil fuels
• Specify filters appropriate to the site
• Use demand control
• Advise on operation – when are the peaks?
• Source control – extract and material spec

20. Move from uncontrolled to
controlled ventilation
• Reduce infiltration (pressure test)
• Don’t over ventilate
• Demand control mechanical systems
• Use real-time information to make decisions on operation
• Is the outdoor air quality bad?
• Can I open the window?
• Should I be using a filtered mechanical system instead?
• Occupant or automatic control

21. Questions?

22. www.cundallconversations.com
@Cundall_Global www.cundall.com
www.linkedin.com/company/cundall
e.wealend@cundall.com
Thanks!