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An update from our TWG's

25 May 2018

Technical Working Group 1: Monitoring and Modelling

Chairs: Tom Cox, Caroline Rye and Valentina Marincioni

At our well-attended inaugural meeting, following a general group discussion, a ‘natural’ monitoring/modelling spilt formed within the working group. This separation was thought to be the most efficient way of working to address the issues and concerns pertaining to the two practices of monitoring and modelling. However, it was also acknowledged that on-going communication between these two factions is considered crucial to the overall success of the group.

Technical Working Group 1 will work to developing Information Sheets to allow interested partied to understand the current capabilities and limitations for both modelling and monitoring of moisture in the built environment. To support both a platform for professionals operating in this area will be explored to provide a trusted and competent source of consultancy.

With regards to monitoring, there seem to be some fairly fundamental questions around the reasons for monitoring and the protocols and methods used. We are in the process of drafting an Information Sheet that could act as an introduction to the subject for those interested in commissioning or carrying out monitoring. In relation specifically to moisture monitoring, we would like to compare different monitoring methods. The first action will be the collation or survey of methods currently in use. Following this we hope to be able to produce a document, another Information Sheet perhaps, detailing these methods and protocols including notice of their limitations. In the longer term we would like to develop a form of quality assurance process which ensures competency for monitoring to ensure confidence in the efficacy of the discipline.

A similar outline to the approach to monitoring was also mapped for modelling of moisture in the built environment. There is a requirement to collate Information Sheets to clearly define and understand what can be reliably modelled and the limitations current software have. To support this, a platform to allow consultancy to demonstrate a level of knowledge, training and continued competence is required.

TWG 1 is planning a workshop on moisture monitoring methods in July to take forward the development of this work stream. TWG members will be informed and invited as soon as the date and time is fixed.

Technical Working Group 2 – Airtightness and Ventilation

Chairs: Ian Mawditt and Tim Sharpe

The key theme in the TWG2 re-launch meeting in October 2017 broadly centred around “what should a ventilation system do and how can we measure what it is doing?”. The use of moisture as a metric for understanding ventilation effectiveness became the focus, using vapour pressure excess as opposed to relative humidity as the convention. In summary, vapour pressure excess (internal vapour pressure minus corresponding external vapour pressure) is a good indicator of the amount of moisture content in the internal air relating to occupant moisture generation. Therefore, could excess vapour pressure be used to understand how effectively a dwelling’s ventilation is able to manage moisture, and other pollutant, concentrations?

Since the meeting, some preliminary research has been undertaken to develop this concept further. Temperature and relative humidity data from some 30 homes (fairly airtight [<6.0] and where context about occupancy and use of ventilation is known) has been re-analysed to explore vapour pressure excess with a view to developing an analytical methodology. The initial results are beginning to reveal some interesting findings. At the time of publication of this newsletter we are not able to present the preliminary results, but we hope to do so in the near future.

The plan will be to develop the methodology and to test it further, using data from dwellings where additional information is available, e.g. ventilation system type, occupancy patterns, etc. If anyone can offer data for re-analysis, then we would like to hear from you. We believe there is a strong case to make a submission for funding to develop this research project further. A potential output would be to develop a simple algorithm with a web front-page where users can simply upload temperature and relative humidity data and further contextual information: they would get feedback relating to moisture conditions against thresholds/benchmarks (to be determined); UKCMB would add the property data to a data repository, allowing further meta-analysis to be performed.

Technical Working Group 3 – New Homes

Chair: Lynne Sullivan

The meeting in October was very productive and well attended. It was suggested that our group (TWG3) should try to involve constructor/developer representatives who are generally poorly represented in the UKCMB at present. Several main themes emerged from the discussions. These were

1. Designing out moisture: air barrier; microporosity, hygroscopicity, reducing thermal bridging; avoiding underfloor condensation; appropriate design for ventilation; flood risk; extreme weather penetration.

It was agreed that better statistical evidence of numbers of moisture-related defects would be very helpful in relation to making the case for further research etc, and that perhaps insurers’ data could be gathered. There was a good discussion about design approaches and skill as well as usability of controls by occupants.

2. Minimising moisture in construction and delivery: Pre-construction protection; During construction issues; drying out periods; Measurement and control of moisture; Ventilation, flow rates, air circulation, purge ability, humidity control, maintenance issues.

It was agreed that more evidence of the performance of ventilation systems of different types under different performance conditions was needed. Also, information on the levels of moisture delivered during the construction period appeared to be sadly lacking, so that KPIs for minimising moisture could not currently be addressed. Of the condensation and mould growth issues reported to NHBC Warranty, those occurring in the first two years were considered defects which the builder is responsible for.

3. Moisture issues in use for occupants: Cleanability; moisture-generating activities; sensors

Technical Working Group 4 – Existing Buildings and Retrofit

Chairs: Harry Paticas and Bob Prewett

TWG 4 met for the first time in October 2017 and attempted to highlight the most important themes relating moisture issues to existing buildings and retrofit. The general consensus was that the next steps should consist of gathering existing research, summarising and then disseminating best practice.

Insulation and fabric

There are a number of areas relating timber and moisture in existing buildings and we have identified the following 3 key areas where existing material should be drawn together.

1. Roof structure and insulation. While loft insulation is commonly considered low risk, a number of sources suggest this may be less so.

2. Suspended timber floors. Again often considered low risk there are increasing studies that may suggest otherwise. It would be god to distil this information and prepare a good practice guide.

3. Joist ends, wall plates and bonding timbers. External masonry walls often include a significant proportion of timber embedded into them. The addition of internal wall insulation can change the moisture conditions of these timbers.

Assessment and Evaluation

A further area of study and potential guidance concerns the assessment of buildings prior to formulating a retrofit/maintenance/remediation programme. Currently there is no formal standard or guidance on this subject, save for general conservation best practice. Both chairs have been evolving an approach to this and, very much rooted in whole house, considering significance as well as developing a deep understanding of existing fabric. It is intended to develop this with an emphasis on moisture management.

Insulation and escape of water

Escape of water accounts for a large proportion of insurance pay-outs. Insulation and air tightness could potentially exacerbate the costs. We propose to explore what mitigation issues could be considered when carrying out retrofit.

Next meeting

This will be held at 11.00am to 1pm (followed by lunch) at UCL Central House on 29th June. TWG members will be contacted directly to confirm their attendance.

Technical Working Group 5 - Flooding and Escape of Water

Chair: Mike Waterfield

This TWG held its second meeting on 25th January

After brief introductions the various work streams were discussed.

It was felt that finding a way to make progress with individual work streams may prove difficult without a better understanding of the issues concerning potential funding. The addition of a colleague from UCL would be beneficial perhaps? [UKCMB agree and will make sure that someone is available in the future]. The four work streams agreed in the initial meeting last October formed the basis of the discussions:

Work Stream 1 (Strip-out of building materials)

It was felt that work stream 1 was an area where the TWG 5 members could be most effective in moving the work forward in the short term. Key issues are:

  • How to identify the correct level of strip out?
  • How to correctly define the reasons for strip out?
  • Barriers to drying the property – Structural degradation of materials – Presence of contaminants
  • Consideration of future resilience and whole life cost

A round table has been proposed with insurers, loss adjusters, restorers, builders and surveyors, with the purpose of identifying good practice and developing an effective decision making process. Prior to this an initial document will be produced as the background for the discussion.

Work Stream 2 (Monitoring of building performance pre and post water damage)

The main questions in this workstream are:

· How do buildings that have not been restored behave?

· How do buildings that have been restored using traditional like for like methods behave?

· How do buildings that have been restored using resilient methods behave?

The group questioned the value of this work stream to industry and insurance, although there may be considerable benefit to owners and occupants. It was considered to be definitely of academic interest but difficult to see any value to potential industry funders. Furthermore access to the relevant categories of properties may prove difficult to achieve.

Work Stream 3 (Determine flood resilience of materials and buildings)

In consideration of the considerable level of interest / work underway / resources within the “Flood Resilience Action Plan” it was felt no further work be considered until more is known about the output from this group.

Work Stream 4 (Mould and Indoor Air Quality)

This topic gave the most enthusiastic debate. Mould and Indoor Air Quality is a topic that is not well understood by many and one that has received much bad press in the past. There is a complete lack of reliable advice for the general public, contractors and insurers. In particular, the questions are:

  • What do we know about the impact of moisture in buildings (from flooding or escape of water) in relation to mould & air quality?
  • What does good practice look like in terms of dealing with mould or IAQ?
  • What current H&S legislation applies to occupants or workers e.g. COSHH?
  • What are insurers liable to pay for when mould & IAQ are linked to a flood or escape of water?

This work requires both academic and industrial funding and engagement. Some of this work has been developed already in UKCMB’s “Mould testing and benchmarking” project, but much more still needs to be done.

Technical Working Group 6 – Insurance

Chair: Jonathan Davison

It was agreed at the meeting of the TWG chairs in January that this TWG would focus primarily on Insurance, rather than also focusing on financial and legal contexts and consequences, as originally planned. This was to ensure a coherent and effective approach to the Insurance industry, who have the main financial interest in water damage in buildings. We were informed that building claims average about £12.5m per day and that escape of water makes up 30% of these, while flooding accounts for about 10% of claims. The insurance industry therefore has a considerable stake in this subject and could be an important driver for change in the understanding of moisture safety in buildings, as well as improvements in remediation techniques and practice.

Consequently, the aims and objectives of TWG6 have been re-written to focus on Insurance. This new document is available on request from anyone interested to be part of this group.

It was also agreed that Jonathan Davison should be the sole chair of this group, taking over from Jeremy Sykes of Polygon. Jonathan is the Strategic Development Director of the British Damage Management Association and has extensive links into the Insurance Industry.

TWG6 aims at influencing the insurance industry and driving change based on the other TWGs outcomes. Sharing of information among TWGs is therefore a key priority for TWG6.