Why you should not need to call in the priest. Topics I can cover. Why moisture can be a problem. The regulations, codes and standards should

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SP01 Health, moisture and dampness in homes Tadj Oreszczyn UCL Energy Institute and

Challenging and Shaping the Built Environment Why you should not need to call in the

problems There is no significant evidence that moisture in walls or on walls is an

and novel constructions Extreme occupant behaviour Why moisture can be a problem?

comment on specific products or constructions Why moisture can be a problem Health

1 SP01 Health, moisture and dampness in homes Tadj Oreszczyn UCL Energy Institute and The Bartlett School of Graduate Studies University College London Understanding, Challenging and Shaping the Built Environment Why you should not need to call in the priest Topics I can cover The regulations, codes and standards should prevent problems There is no significant evidence that moisture in walls or on walls is an increasing problem There will always be some problems Poor workmanship New materials and novel constructions Extreme occupant behaviour Why moisture can be a problem? At wall surfaces In walls Why we do not have all the answers Not the person to comment on specific products or constructions Why moisture can be a problem Health related issues associated with mould growth and mould growth and house dust mites Deterioration of fabric 1

2 So what is wrong with a bit of mould? Significant but controversial evidence that mould can exacerbate respiratory and a range of other problems. Most recent National Mental Health Survey 2

Asthma, Moulds, Mites and Relative Humidity 60 Variation in major health problems with energy efficency of dwelling Source: Englich House Condition Survey 1996 Energy Report Asthma costs the UK 2

The majority of asthmatics are sensitised to house dust mite faces and mould spores and that relative humidity is a key environmental parameter in the control of the population of HDM and mould

3 Asthma, Moulds, Mites and Relative Humidity 60 Variation in major health problems with energy efficency of dwelling Source: Englich House Condition Survey 1996 Energy Report Asthma costs the UK 2 billion per annum in fatalities, medication, and lost working days[1]. The majority of asthmatics are sensitised to house dust mite faces and mould spores and that relative humidity is a key environmental parameter in the control of the population of HDM and mould growth 15% of English dwellings have mould growth (1996 EHCS) with rating having any th problem % of people in homes w major healt [1] Mr. Chaytor, Oral Answers to Questions, Commons Hansard Debates text for Tuesday 6 May 2003, Volume No. 404, Part No. 389, Column inefficient Less than or more Energy Efficiency / SAP efficient % increase in health problems in households with moderate or sever mould Mould versus energy efficency % No smokers lems in households sever mould % increase in health probl with moderate or s 150% 100% 50% 0% Smokers Asthma Bronchitis Wheezing Hay fever Allergic Rhinitis Eczema olds with mould % of househo Slight Moderate Severe <10 10 to >60-50% Health problems Source: Englich House Condition Survey 1996 Energy Rep Energy efficecny / SAP Source: Englich House Condition Survey 1996 Energy Report Variation in Asthma with Energy Efficiency % of people with asthma Less than or more Energy Efficiency / SAP Source: English House Condition Survey 1996 Energy Report 3

The 5 stages of the mite life cycle (duration in days at 23 o C and 75% from Arlian et al 1990) Egg (8.1) Larva (10.4) (4.

4 quiescent) Effect of temperature on egg-to-adult development /days Duration / 140 120 100 80 60 40 20 Egg to adult duration at various temperatures

1990) Typical bedroom temperatures 0 10 15 20 25 30 35 40 Temperature/C Occupied bed temperatures House Dust Mite Results Reducing ventilation from 0.

4 ach = 100 x more mites Raising bedroom temperatures from 16ºC to 18ºC = ten times less mites Increasing the number of occupants from 4 to 6 =

4 The 5 stages of the mite life cycle (duration in days at 23 o C and 75% from Arlian et al 1990) Egg (8.1) Larva (10.4) (4.0 quiescent) Adult male (77) & female (31) Egg to adult (33.7) Protonymph (6.9) (3.2 quiescent) Tritonymph (8.3) (3.4 quiescent) Effect of temperature on egg-to-adult development /days Duration / Egg to adult duration at various temperatures at 75% RH (from Arlian et al. 1990) Typical bedroom temperatures Temperature/C Occupied bed temperatures House Dust Mite Results Reducing ventilation from 0.5 to 0.4 ach = 100 x more mites Raising bedroom temperatures from 16ºC to 18ºC = ten times less mites Increasing the number of occupants from 4 to 6 = 10,000 more mites. Highest mite populations should occur in SW England, followed by Northern Ireland, with London having the lowest. Climate change will result in a significant increase in mite populations. For example a typical bed in London is predicted to have 80 times the population of mites in Simple calculations indicate that a mattress may theoretically be able to sustain up to 1.5 million mites Temperature Relative eat ehumidity dty Moisture Must control both 4

5 5

6 To avoid surface mould growth Keep air RH below 70% Avoid cold bridges We are very bad at detecting RH! Sensitivity to changes in RH and temperature Human comfort (How good were you at predicting the RH compared to T?) 4% change in RH equivalent to 0.1 C change in temperatures (100% RH change can be compensated by a15to3 1.5 C temperature change Objects (moisture sensitive) 4% change in RH equivalent to 10 C change in temperature Objects are 100 times more sensitive to RH relative to temperature compared to humans 6

ENVIRONMENT ENERGY VENTILATION 50 45 Changing standards of air tightness Build Tight Ventilate

9 ach) 15 10 5 0 0.25 0.5 0.75 1 1.25 1.5 1.75 2 2.25 2.5 2.75 3

R Gammage & S Kaye, Lewis Publishers, Michigan, 1985 http://www.greenspec.co.

7 ENVIRONMENT ENERGY VENTILATION Changing standards of air tightness Build Tight Ventilate Right % of sample New homes (Median 0.5 ach) Old homes (Median 0.9 ach) Infiltration rate (ACH) From Indoor Air & Human Health, Eds. R Gammage & S Kaye, Lewis Publishers, Michigan, Ventilation Performance Criteria for Dwellings (BRegs 2006) Mould NO2 CO TVOC Bio-effluents Energy Efficient Ventilation, 2006, EST 7

Domestic ventilation the balance between health and energy Energy Critical RH for house dust mites Ventilation 20% of the average UK

Surface condensation Interstitial condensation Salts Moisture content of fabric is critical for deterioration (e.g.

t in timbers of about 20 per cent Optimum growth occurs at 30-40 per cent Spore germination requires wood moisture content of 30 per cent

fungus is rapidly killed above 40 C WET ROTS Wet rot fungi usually occur in persistently damp conditions needing an optimum moisture

8 Domestic ventilation the balance between health and energy Energy Critical RH for house dust mites Ventilation 20% of the average UK building heat loss Fabric conservation FUNGI WHICH INFEST BUILDING MATERIALS Frost damage Moisture damage Rain penetration Rising damp Surface condensation Interstitial condensation Salts Moisture content of fabric is critical for deterioration (e.g. 20% moisture content for moisture resistant flooring) Moisture Conditions and Temperature Requirements DRY ROT Minimum i moisture content t in timbers of about 20 per cent Optimum growth occurs at per cent Spore germination requires wood moisture content of 30 per cent The optimum temperature for dry rot growth in buildings is about 23 C, the maximum temperature for continued growth is about 25 C and the fungus is rapidly killed above 40 C WET ROTS Wet rot fungi usually occur in persistently damp conditions needing an optimum moisture content of per cent Wood-rotting fungi differ in their optimum temperature but for most the range is between C 8

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10 DBIC5HQBVcYVXNdqIPmyq0Ko510=&h=235&w=380&sz=12&hl=en&start=1&itbs=1&tbnid=HISkpcnWOz9LyM:&tbnh=76&tbnw=123&prev=/images% 3Fq%3Dinterstitual%2Bcondensation%2Bwall%26gbv%3D2%26hl%3Den NBT Breathability Matters Why the Kingspan White Paper is seriously misleading Introduction: In March 2009 Kingspan produced a White Paper on Breathability subtitled: A study into the impact of breathability on condensation, mould growth, dust mite populations and health. On the front page was a picture of a red herring. The executive summary concluded Breathable constructions and the breathability of insulation products are therefore at best a side show, in reality they are a complete red herring in the avoidance of surface condensation, mould growth and exacerbated dust mite populations. An article in the autumn 09 issue of Green Building by Phil Heath refers to this document and re-iterates its main theme. In this article we accept that the basic data provided by Kingspan was mainly correct; furthermore the basic assertion that vapour open walls (which Kingspan call breathable walls ) are not an effective way of transferring moisture from the inside of buildings to the outside when compared to bulk air exchange (ventilation plus air leakage) was also correct. However the argument itself is entirely wrong in asserting that breathability is not important for the prevention of mould growth, dust mite populations and other sick building syndrome. What Kingspan and their consultants have done is set up a false target (the use of vapour open constructions to convey moisture to the outside of buildings) which has been easy to knock down, and in doing so have attempted to undermine all arguments about breathability. This is not only misleading but it is also dangerous for building and occupant health, and as such is highly irresponsible. Where breathability matters: There are two areas where breathable conditions are vital. These are Fabric health, particularly in situations of building faults Human health through the prevention of moulds and through the buffering of internal relative humidity Neil May 6 th November

Why it is so difficult Many complex things to take account (some of which are not intuitive) Material properties are not well defined Measuring and monitoring i reality is difficult Not visible No

production mean internal vapour pressure bed characteristics Schematic representation bed hygrothermal of factors affecting the conditions hygrothermal environment in a dwelling dust mite population

way a material absorbs and desorbs water vapour as the relative humidity changes, measured by the change in water content (as a percentage of the mass) in a material when stabilised (Equilibrium

11 Why it is so difficult Many complex things to take account (some of which are not intuitive) Material properties are not well defined Measuring and monitoring i reality is difficult Not visible No good sensors Long term effects fuel expenditure mean internal temperature ambient conditions occupant behaviour ventilation rate hygrothermal conditions of zone dwelling characteristics moisture production mean internal vapour pressure bed characteristics Schematic representation bed hygrothermal of factors affecting the conditions hygrothermal environment in a dwelling dust mite population Critical moisture properties Measuring and monitoring Vapour Permeability - the way a material allows water vapour to pass through it, measured as vapour resistance(r), in MNs/gm Hygroscopicity - the way a material absorbs and desorbs water vapour as the relative humidity changes, measured by the change in water content (as a percentage of the mass) in a material when stabilised (Equilibrium Moisture Content) after a change in relative humidity, typically from 50% to 85%. The speed of absorption of moisture is also very important. Capillarity - the way a material absorbs water as a liquid, measured as the amount of water absorbed by one surface per m2 per hour (w). UK -waterproofing technology could cut home energy consumption by 30 per cent. Scientists at the University of Portsmouth investigating the effects of applying a silicone-based compound to a test house found that in wet conditions the amount of energy needed to heat the house was cut by almost a third. This would cut the average heating bill on a semi-detached house with loft insulation and double glazing by over 100 per year. The project was part of a government competition to find innovative solutions for improving the environmental performance of the UK's housing stock. Housing in the UK accounts for 27 per cent of carbon emissions and more than 80 per cent of the houses we will live in by 2050 have already been built. 11

STBA Work with DECC. A New Approach to Moisture Risk Assessment and Guidance. Neil May STBA, UCL, NBT

STBA Work with DECC. A New Approach to Moisture Risk Assessment and Guidance. Neil May STBA, UCL, NBT STBA Work with DECC A New Approach to Moisture Risk Assessment and Guidance Neil May STBA, UCL, NBT STBA Sustainable Traditional Buildings Alliance For people & environment Pre 1919 (mainly masonry) Domestic