Richard Evans, Condensation and Mould Specialist for
Medway Towns, Maidstone, Canterbury and surrounding areas
Design Manufacture Survey Install Maintain
Agenda
Scoping the problem
Who is legally responsible?
Causes?
Possible Solutions
Choosing the best solution
Plan of action
Costs?
Questions?
How big is the problem?
1 in 5 of all UK properties suffer
from Condensation
Perhaps 1 in 3 tenanted
properties suffer from
condensation!?
Are we responsible for stopping it?
Housing Health and Safety Rating System
The requirement is that a dwelling should be
free of category 1 hazards.
Hazards in Group A are classed category 1.
Hazard Group A - Physiological Requirements
Damp & Mould Growth
Description of the hazard
1.01 This category covers threats to health associated with increased prevalence of house
dust mites and mould or fungal growths resulting from dampness and/or high humidity's.
It includes threats to mental health and social well-being which may be caused by living in the
presence of damp, damp staining and/or mould growth.
Why?
Health
Dust Mites
Commonly considered the most common trigger of Asthma
Initial exposure can result in long-term asthma
There is an asthma sufferer in every five households in the UK
Tobacco Smoke and Particulates
5-10% of all lung cancer is linked directly to passive smoking”
“Babies and children in smoky atmospheres are
twice as likely to have asthma and chest
infections as well as coughs, colds and
wheezes”
What causes it Tenant or Landlord / Property?
Sources of Condensation
Water Source
Litres (per
day/activity)
Litres/day for an
occupancy of 4
Notes
Breathing
1.5
6
Washing and drying clothes
1.5
2.5
Showering
1.5
4.5
Bathing
0.75
0
Cooking
1.0
1.5
Washing floors
1.0
1.0
Large House Plants
0.5
0.5
each
Seasonal Storage from
furnishings and building fabric
0.9
0.9
Estimated as a rate to lose
5% in wight over 4 months
Construction (eg rain/water
ingress as vapour through wall
brickwork/ cellar )
0.5
0.5
Not measured. Figures are
nominal
Construction
(new build)
?
?
Perhaps 3000 litres total.
Most comes out in first 2 to
3 years
Totals
In most established rented property the daily total might typically be 15+ litres
1.5 ltrs/4.5 kg spun laundry
Gas cooking creates more
than electric
Figures are ‘interpreted’ from the pure data within the below publications. To make sense of the variations, some qualitative assumptions have been made about current UK lifestyles. Where there
are significant differences in the raw data, effort has been made to retain the general ratios within the data sources;
Hiss-reet http://www.hiss-reet.com/constructions-with-reed/thatched-roof/thatched-roof-architecture/thatched-roof-ventilation.html accessed 17.02.11
National Research Council of Canada http://www.nrc-cnrc.gc.ca accessed 17.02.11
American Society of Home Inspectors http://www.homeinspector.org/resources/journals/Moisture-in-homes.pdf accessed 17.02.11
Tenant Related
1.High Occupancy rates
2.Multiple showers
3.‘Blitz’ heating regimes
4.Working from home
5.Cooking types
6.Closed Windows
7.Doors closed
8.Clothes dried on hot radiators
9.Closing/blocking of vents
Building Related
1.Poor Ventilation / ductwork
2.Small Rooms
3.Orientation
4.Exposure
5.Glazing
6.Insulation
7.Wall construction
8.Restricted chimneys
9.Furnishings and structural components
10.Heating Method
Solutions
Fungicidal paint
Pros
• Easy
• Low cost (c.£50 per room + labour)
Cons
• Air quality (smoke, dust mites, existing
spores)
• Active ingredient is soluble
Insulated wall linings
Pros
• Reduces heat loss
• Good for highly localised problems
Cons
• Not effective in isolation –simply moves problem
Dehumidifier
Pros
• Easy
• Relatively low capital cost (£100-£200 per room)
• Good for acute emergencies
Cons
•
•
•
•
Running costs - £10/month/room (400 watts, 8hrs/day)
Noise
Regular Maintenance (weekly and annual)
No effect on air quality (smoke, etc)
Passive Ventilation
Air Bricks/Window Vents
/Trickle Vents
Pros
• Relatively low ££ if DIY (Passyfier vents c. £80 each+
install)
Cons
• 4-10 needed per property (MAXIMUM airflow 2l/s)
• Still need MV for Kitchen and bathroom(s)
• “If you can’t feel a draught, they’re not working”
- Airflow Ltd.
• Cold bridging
Mechanical Ventilation
Pros
• Only solution to actively address the problem
• Long lasting (subject to quality)
• Minimal maintenance
• Can be outside tenant control
• Improves air quality
• Minimal ongoing costs
Cons
• Initial Outlay
(typically £600-£1800 / property inc VAT & installation)
Extraction
- sucking out the moisture (and heat)
from the periphery,
drawing in lower humidity, ambient air
from outside
What Extraction for Condensation?
Intermittent
Light/timer controlled
Semi Continuous
Humidity controlled (humidistat)
I
Continuous
Trickle
Humidity controlled
Humidity tracking
Continuous Humidity Tracking
Maximum Fan Energy Efficiency
Winner, Queens Award for Innovation 2009
Our bathroom unit – typically 1W (max 7W) -around £2 per annum
Our kitchen unit – typically 2W (max 26W) around £4 per annum)
Life expectancy? – min 5 years and still going strong since 2004!!
Positive Input
Ventilation
(blowing in lower humidity air centrally,
forcing out the stale air)
Positive Input Ventilation
Most cost-effective solution for
Bedrooms and Living areas.

Core benefits of MVHR (Heat
Recovery) at a fraction of the cost

Actively takes advantage of the
leakage of non-CSH properties

Positive Input Ventilation

Trickles air in diluting, fresh air continuously

A single loft unit recovers heat energy and
controls a 4 bedroom house
(a wall unit controls a 3 bedroom flat)

Redistributes otherwise lost heat

Creates a fractionally pressurised environment,
reducing draughts by c.66%
How we assess the best solution(s)
On a per property basis:
Constructional aspects
Tenant behavioural/occupancy aspects
Existing Ventilation Performance
Layout
Internal/external Relative Humidity Levels throughout
Air and Wall Temperatures
Wall and loft Moisture Contents

Costs
Preferential Rates 2011
•
•
•
•
•
Single Room Unit
Single Room Heat Recovery Unit
Multiple Wet Rooms Unit
Loft Mounted House PIV
Wall Mounted Flat Unit
£249* (TSP £299)
£TBC* (TSP £399)
£525 (TSP £650)
£535 (TSP £799)
£615 (TSP £899)
– Plus Insulated ductwork and Box profile if needed @ £100/metre
*(£15 premium applies if single unit install)
All above figures include standard installation charges but exclude VAT
Plan of Action
1. Choose and apply your solution
2. Wait a week or so
3. Remove all mould (with fungicidal wash /
vacuum brush / dampened cloth)
4. Redecorate if needed
5. Thoroughly clean furnishings (eg Safeclean)
Summary
Control indoor humidity and you solve much more
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