No Insulation Without Ventilation Peter Rickaby Rickaby Thompson Associates

Transcription

1 Creating an Energy-Chic Home The Highgate Society, 8 February 2017 No Insulation Without Ventilation Peter Rickaby Rickaby Thompson Associates

2 No Taxation Without Representation Rickaby Thompson Associates Ltd 2

3 No Insulation Without Ventilation Rickaby Thompson Associates Ltd 3

4 No Insulation Without Ventilation Ventilation is critical to IAQ and to successful retrofit Don t default to MVHR For retrofit there are usually better options Demand-Controlled Ventilation The emerging ventilation system for homes Rickaby Thompson Associates Ltd 4

5 Air Leakage and Ventilation 50 Pa Air Permeability Air Infiltration and Air Leakage Ventilation Rickaby Thompson Associates Ltd 5

6 Air Leakage and Ventilation Air Permeability Air Infiltration and Air Leakage Ventilation Rickaby Thompson Associates Ltd 6

7 No Insulation Without Ventilation If we install any measure that reduces infiltration Loft insulation Cavity wall insulation Solid wall insulation Floor insulation New windows and external doors Draught-proofing We must compensate for the lost infiltration Assess the existing ventilation (if any) Upgrade to an adequate ventilation system Otherwise the consequences are Poor IAQ, condensation, mould Rickaby Thompson Associates Ltd 7

8 Why We Need Fresh Air Provision of oxygen for breathing Dilution and removal of air borne pollutants Control of excess humidity Supply of air for fuel burning appliances Maintenance of healthy indoor air quality Rickaby Thompson Associates Ltd 8

9 Typical Indoor Pollutants CO 2 Odour Particulates Pollen Ozone Moisture Bacteria & mites VOC s Formaldehyde Tobacco smoke Based on: AIVC Guide to Ventilation Rickaby Thompson Associates Ltd 9

10 Controlling Moisture Control internal moisture build-up To ensure good internal air quality By keeping RH between 40% and 60% To reduce surface condensation risk On cold surfaces and at thermal bridges Control moisture movement through the fabric To prevent moisture penetrating the fabric Or manage moisture that does penetrate From inside or outside To eliminate interstitial condensation Where warm moist air meets a cold surface Rickaby Thompson Associates Ltd 10

11 Ventilation Options Intermittent extract fans * IEV Passive stack ventilation * PSV Heat recovery room ventilators Supply and extract HRRVs Continuous mechanical extract* Centralised MEV Decentralised MEV MVHR Whole-house supply and extract Rickaby Thompson Associates Ltd 11

12 Ventilation Options Intermittent extract fans * IEV Passive stack ventilation * PSV Heat recovery room ventilators Supply and extract HRRVs Continuous mechanical extract * Centralised MEV Decentralised MEV NOT GOOD ENOUGH FOR AIR-TIGHT HOMES CONTINUOUS VENTILATION IF AIR PERMEABILITY < 5 m 3 /m 2 50 Pa MVHR Whole-house supply and extract Rickaby Thompson Associates Ltd 12

13 Design of MVHR Systems Heat exchanger Inside insulated envelope Motor and fan design Efficient fans, DC motors Summer by-pass of HR Essential to avoid overheating Ducting Inside insulated envelope Large diameter, smooth bore Short straight ducts Slow bends Manifold + room ducts Installation Use specialist installer Commissioning is critical Maintenance Access required Rickaby Thompson Associates Ltd 13

14 Don t Default to MVHR MVHR was developed for new Passive Houses Provides good IAQ Recovers the ventilation heat loss Distributes the small heat input Passive Houses are designed around MVHR Plant room, careful routing of short, straight ducts Efficient MVHR does not fit easily into Victorian terraced houses 1930s semi-detached houses 1960s flats MVHR that is crammed in will be Inefficient, expensive and noisy Difficult to maintain Switched off by residents! Rickaby Thompson Associates Ltd 14

15 Demand Controlled Ventilation Principle Control of air supply or air extract rate by RH and/or CO 2 sensors Ventilation when and where required No whole-house boost mode Efficient, room-by-room control Practice (DC MEV) RH sensors in air inlets Nylon strips respond to RH Optional CO 2 sensors in rooms Control fan speed Ventilation responds to RH and/or CO 2 Fan responds to RH or inlet aperture Rickaby Thompson Associates Ltd 15

16 Summary Ventilation of retrofitted dwellings is critical To ensure IAQ and avoid condensation and mould No insulation without ventilation Ventilation strategy must relate to fabric strategy Effective ventilation requires good air-tightness There are many ventilation options Intermittent/continuous EV, HRRV, PSV, MEV, MVHR Select appropriate systems - don t default to MVHR! Demand controlled ventilation Ventilates efficiently when and where required Tracks internal RH (and sometimes CO 2 ) Easy to retrofit (demand controlled MEV) Rickaby Thompson Associates Ltd 16

17 Creating an Energy-Chic Home The Highgate Society, 8 February 2017 No Insulation Without Ventilation Peter Rickaby Rickaby Thompson Associates