Ventilation in new. homes HVAC 2016 NICOLA O CONNOR AND JOHN KELLY

Transcription

1 Ventilation in new homes HVAC 2016 NICOLA O CONNOR AND JOHN KELLY

2 What is the problem? Indoor air pollution Ventilation systems are not performing as required by Building Regulations Airtight dwellings + underperforming ventilation systems = indoor air pollution = potential health problems Indoor pollutants can become more abundant inside an energy efficient, airtight envelope 2

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4 Ventilation study Published March

5 Tests carried out Air flow rates Ventilation system air flow rates were measured in test units Air exchange measurements Air exchange measurements are useful for understanding the performance of ventilation systems in dwellings. The method chosen was a tracer gas decay test which measures the physical air exchange that takes place in a given volume

6 How did the MEV systems perform? Results anonymised Less 50% of required duty 6

7 How did the MVHR systems perform? Site 2: measured ventilation rates also slightly low (except unit 2D) 7

8 Site 1 Site walk-throughs Example 8

9 Site 1 - Did the construction team have processes in place to enable high quality delivery of the ventilation systems? Good practice observed Yes. The Site Manager knew what was expected at first and second fix. Drawings indicating the ventilation routes were available in the site office. Regular meetings were held between the Site Manager and the design team. Examples from other sites Designs were carried out in house without full consultation with the installer.

10 2. Were the designs/ ventilation strategies suitable for the scheme and sufficiently detailed? Problems observed No in some cases. Some of the ducting and fans were missing from the construction layout drawings for one unit, which was then missed by the installation team at first fix in their attempt to be faithful to the drawings. Remedial works were carried out by the electrician which resulted in flexible ducting being installed instead of specified rigid ducting. Examples from other sites Designs did not take into account fire compartments nor were they coordinated with soil vent pipe positions, meaning duct lengths were increased by up to 6 metres compared to the drawings.

11 3. Were systems and ducting installed in accordance with the designs? Good practice observed Yes. The ducting broadly followed the routes on the design layout. However, in the unit where the drawings had missed off the ventilation system, flexible ducting was installed. This ducting was too long and sagged. The other units had rigid ducting installed, as designed. This picture: Long looping ducting could cause condensation to build up and increase the required fan power Examples from other sites The design did not specify the duct type which resulted in duct selection decisions being made on site. In some loft spaces the ducting was not connected to the roof vent. A kitchen duct in one unit was 12 metres in length.

12 4. Were trickle vents and background ventilators installed in accordance with ADF? Problem observed No. All the windows installed had trickle vents, including the wet rooms. This was thought to be an error by the window supplier. There was also more than double the Equivalent Area required.

13 5. Were door undercuts provided to the correct height? Problem observed No. Door undercuts were inconsistent. Approximately 20% of internal doors had door undercuts of <10mm in all the dwellings inspected.

14 6. Were ventilation systems commissioned in accordance with the Domestic Ventilation Compliance Guide? Problems observed No. The Site Manager was not aware of any checking of air flow rates taking place. Examples from other sites Neither the installer nor the on-site team were aware of the ADF requirement for commissioning. There was no evidence that full commissioning was routinely performed.

15 7. Were handover processes carried out and the ventilation system delivered to occupants in a good state? Good practice observed The handover procedure was very good. There was a full explanation of the ventilation system, controls and trickle vents with a checklist provided for the Site Agent to work through. Some issues. The external ventilation grilles in 40% of dwellings were not cleaned out properly before handover (they contained mortar and debris). Noisy fans Above - Mould in a cupboard at a Show Home inspected. Example of the risk of under-ventilation, including during the building drying-out phase. Sales staff had switched off fans as they were too noisy due to poor installation. Examples from other sites Occupants interviewed did not know they had an MVHR system and were therefore unaware of the need to change the filters.

16 Performance Gap Things going wrong at every site visited, at multiple stages At five of the six sites, fans were operating at only half the required duty or lower Cumulative effect of the issues ultimately outweighed the good practice found and resulted in minimum standards not being met.. 16

17 Things to look out for Compliance Designs deliverable on site? Changes on site Flexi duct and duct run lengths Requirements for dmev systems Commissioning Handover materials Case study teams are reviewing processes

18 Strategic actions Mandatory training Communication between the design team and the team on-site - require Quality checks at each major stage of the construction process 18

19 Indoor Air Quality The Role of Good Ventilation Installation and Competence

20 Good Practise Testing and Commissioning stage Check that individuals carrying out commissioning are trained and registered under a Competent Persons Ventilation installer Scheme. There are benefits in SAP for using an accredited installer Check that commissioning sheets have been fully completed for each property. Check that MVHR filters have been replaced or cleaned prior to handover, Check all control systems function correctly Check that external grilles have been cleaned and are free from debris. Use correct and UKAS calibrated measuring instruments Handover stage Occupants should be provided with a full explanation of the ventilation system controls and operation. System information should be left with the occupants, including details of maintenance requirements. i.e. Routine fan cleaning, replacement of filters (MVHR units)

21 NEW - Competent Persons Ventilation Installer Training Scheme Ventilation training courses exist but none have been a true Competent Persons accreditation BEAMA (A Ventilation sector trade association) has been proactive in working with NECEIC to create a Training and Audited registration scheme for Residential Ventilation Installers Qualification will allow demonstration of a high level of competence for supply, design, installation, commissioning and handover of a domestic ventilation system.

22 Raising Competence is a Shared Responsibility Manufacturers - Produce products which are fit for purpose meeting the requirements of latest Building Regulations and delivering Installed Performance - Provide clear instructions and easy to understand operating documents for handover to occupiers - Facilitate training and education of ventilation installers

23 Raising Competence is a Shared Responsibility Housebuilders and Developers - Select and monitor qualified, Competent Installers who understand the importance of best practise installation -Specify products which will meet the requirements of the specific house type / renovation -Insist on liaison with the architect / designer where logistical issues arise. (Don t just run longer lengths of flexible ducting to get around obstacles not on drawings) -Inform householder on handover how their ventilation system works and how it should be maintained

24 Building Control Raising Competence is a Shared Responsibility - Greater education in fully understanding the detail of the Building Regulations and Domestic Ventilation Compliance Guide - Better policing of installation documentation and understanding the impact of poor ventilation installation on air movement before signing off Government - Further recognition that Best Practise ventilation installation is an important skillset

25 Summary By all stakeholders working together to raise standards of ventilation installation through the provision of good design, quality performing products and installer training to deliver Best Practise on site, we will provide improved Indoor Air Quality Thank you for your attention