This document discusses solutions to overcome overheating in apartments. It begins by highlighting that overheating and noise are significant problems according to surveys. It then discusses regulations and standards around overheating before examining passive and mechanical design solutions. Passive approaches include orientation, shading, high thermal mass, natural ventilation. Mechanical options include MVHR systems, with or without additional fans, heat pumps or cooling coils. The document compares performance and costs of different ventilation solutions.
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Mark Harber - Design solutions to mitigate apartment overheating
1. Design Solutions to Overcome
Apartment Overheating
2 2 ND J UN E 2 0 2 0 - MARK H ARB ER.
IAQM Indoor Air Quality Conference
2. Cool & Quiet.
− A real issue – why it matters.
− Overheating in our homes.
− Noise and air quality impact to occupants.
− Solutions: what we’ve learnt & our vision.
Balancing overheating &
noise through good design
3. “In a survey of people involved in managing or
building homes, 80% said overheating was a problem
and 65% confirmed this was a significant concern for
their organisation” Source: Investigation into Overheating in Homes, 2012
4. “48% of the 2,750 people surveyed in England
and Wales felt that their home life was being
spoilt by noise, with one in five saying it kept
them awake at night” Source: UK National Noise Attitude Survey 2012
5. Camden High Street 1904
Westminster Serves
“The Tenant was faced with a no-win situation
where if things had remained, the tenant would be
expected to choose between either the problem of
excess noise or excess heat”
Improvement Notice to
Landlord.
July 2012 issue 64
6. “Almost 30% of people would be willing to pay
more for a home that enhanced their health and
wellbeing”
T H E U K H O M E , H E A L T H A N D
W E L L B E I N G R E P O R T , S A I N T
G O B A I N , 2 0 1 6
8. “The phenomenon of a person experiencing
excessive or prolonged high temperatures within
their home, resulting from internal and/or
external heat gains, and which leads to adverse
effects on their comfort, health or productivity”
Z E R O C A R B O N H U B , 2 0 1 5
9. Regulations / Compliance- Part L ‘Criterion 3’
Overheating
− Part L1A of Building Regulations endeavours to address dwelling overheating with
“Criterion 3”
− “The dwelling should have appropriate passive control measures to limit the effect
of heat gains on indoor temperatures in summer”
− This check is often overly simplistic and does not provide an accurate indicator of
overheating risk
− It also does not take account of site constraints, such as acoustics or air quality
− As such, compliance can usually be easily achieved by assuming openable windows
− When windows are simulated closed then compliance can often be achieved with
enhanced mechanical ventilation rates of 2-3 air changes per hour
11. What is it?
Overheating
Adaptive Criteria (less onerous, allowing higher internal
temperatures, linked to outside air temperatures)
Fixed Criteria (<3% of occupied hours >26oC)
Mechanical Ventilation Natural Ventilation
12. CIBSE Guidance
Overheating
0
5
10
15
20
25
30
35
Temperature(C)
London Weather Centre
Dry-bulb temperature (°C) Max. adaptive temp. (°C) FixedModel - ThresholdTemperature (°C)
− Fixed (<3% occupied hours above a fixed
maximum temperature of 26oC)
− Adaptive (Less onerous criteria, allowing
higher internal temperatures, linked to
outside air temperatures)
− The Adaptive method applies to
predominantly naturally ventilated
dwellings.
− The Fixed method applies to predominantly
mechanically ventilated dwellings.
13. What does it actually mean?
Overheating
− 50% June and 70% of July exceed the threshold.
− Peak period in July of 6 days when internal temperature
does not drop below the threshold of 26oC.
− In July there are 6 nights when temperature does not fall
below the threshold of 26oC and 16 nights when above
threshold for part of the night..
15. GLA Cooling Hierarchy (and Good Practice).
Overheating.
1. Minimise internal heat generation through energy efficient design
2. Reduce summer heat gains: orientation, shading, albedo, fenestration,
insulation, green roofs/ walls
3. Exposed internal thermal mass and high ceilings
4. Passive ventilation
5. Mechanical ventilation
6. Active cooling systems (selecting the lowest carbon options)
Passive design
Active design
16. Passive Design
Overheating
Window openings and
(integrated) blinds Cross ventilation
Indicative glazing
proportions
Movable
shutters
Other potential shading measures
Façade:
− Building orientation & massing
− Dual aspect apartments- courtyards for acoustic shielding
− Glazing areas balancing solar vs daylight vs views
− Suitable glazing g-value & visible transmittance
− External shading (balconies, etc), shutter design.
− Consider thermal mass (albeit generally not helpful in
bedrooms, as it affects night-time temperatures)
Ventilation:
− Practical & effective ventilation opening areas (windows &
doors)
17. Residential Corridors
Overheating
− TM59 stipulates <28oC for under 3% annual hours.
− Utilise lower temperature heating distribution pipework
− Locate risers / utility cupboards so as to minimise horizontal
pipework runs
− Ventilate LTHW risers
− Enhanced insulation to pipework distribution - including bends
and fittings
− Maintain separation of cold water and heating pipework to
avoid temperature pick up
− Utilise smoke ventilation shafts for additional ventilation as a
minimum and consider tempering supply make-up air
20. Risk category
Internal sound levels
Implication
Day Night
>50 dB LAeq >42 dB LAeq
High Risk Category
Open windows unlikely
to be acceptable.
40-50 dB LAeq 35-42 dB LAeq
Moderate Risk Category
Open windows may be
acceptable for limited
periods of time.
35-40 dB LAeq 30-35 dB LAeq
Low Risk Category
Open windows is not
likely to result in adverse
effect
≤35 dB LAeq ≤30 dB LAeq Negligible
Noise
How much noise is acceptable?
22. Applying the AVO Guidance
Noise
Predicted Acoustic Risk Categories – Complete for day and night!
23. Ventilation Design Impact
Air Quality
− The importance of improving air quality has been recognised by
the GLA and features in the London Plan.
− A detailed assessment of local sources of air quality would be
undertaken to determine air pollution concentration at the
different façades across the development.
− Air quality mapping can then be completed and risk categories
assigned (similar to Acoustics) to consider whether opening
windows are feasible.
− Typical AQ mitigation measures for apartment ventilation
systems include:
- Inclusion of NOx filtration on the intake air connection of the
MVHR
- Bringing outside air in from roof level via an intake air shaft
25. Regulations / Compliance- Part F
Apartment Ventilation
− Opening windows need to be provided to all habitable rooms for
purge/rapid ventilation.
− Background ventilation to each dwelling to comply with one of
the following systems set out in Part F.
- System 1- Intermittent extract fans and trickle vents
- System 2- Natural passive stack and trickle vents
- System 3- Continuous extract fans and trickle vents
- System 4- Continuous supply and extract system (MVHR)
− Part F minimum mechanical ventilation rates are minimal and
would not meaningfully deal with overheating.
− MVHRs are used in 95% of our residential projects (especially in
London where the heat recovery is needed to meet the GLA
energy targets).
Fresh-Air into Dwelling
Stale-Air Extract
Stale-Air Exhaust
Incoming Fresh Air
Heat Recovery Mode
Summer Bypass Mode