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NZEB: Ventilation in dwellings


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Simon Keogh presents on ventilation in dwellings in the NZEB session at the SEAI Energy Show.

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NZEB: Ventilation in dwellings

  1. 1. Ventilation in Dwellings Simon Keogh Senior Architect John Doran Senior Mechanical Engineer Hayes Higgins Partnership RIAI Sustainability Task Force
  2. 2. Overview Part F Dwellings – New 1. New Regulations - 3 ventilation systems 1. MEV (Mechanical Extract Ventilation) 2. MVHR (Mechanical Ventilation Heat Recovery) 3. NV (Natural Ventilation) commonly known as ‘trickle vent’ 2. Current NV challenges 3. Mechanical Systems 4. Impacts on Space 5. Wireless Sensor Networks – IAQ
  3. 3. Introduction - Current legislation The Building Regulations TGD F 2018 DRAFT describes 3 main systems of ventilation: Section Type AP (Air Permeability) 1.2.2 (c) Mechanical Extract Ventilation (MEV) < 3 m3/m2/hr 1.2.3 Mechanical Ventilation Heat Recovery (MVHR) < 3 m3/m2/hr 1.2.4 ‘Natural Ventilation’ (NV) E = 7000 mm2 trickle vents to habitable rooms PLUS • total minimum 42,000mm2 • 7000 mm2/10sqm over 70sqm • mechanical extract ventilation from wet rooms 3- 5m3/m2/hr Table 1 1.2.1 Other approaches may be adopted to meet Building Regs (The Requirement F1)
  4. 4. Introduction - Current Legislation Part F acknowledges that as the standard of air tightness increases in Part L , the holes in the walls need to get bigger by 40% CONFLICT = The efficiency of air tightness is lost through additional ventilation
  5. 5. Introduction - Ventilation Purpose Ventilation systems controls the quantity and quality of air passing through the dwelling to control 1. Carbon Dioxide 2. Moisture and humidity 3. Draughts 4. Volatile Organic Compounds (VOC) 5. Carbon Monoxide 6. Smells and odours 7. Mould and bacteria 8. Noise 9. Dust and dirt …OR just comfortable healthy buildings for Irish citizens
  6. 6. Natural Ventilation (NV) – a short history of mould We also had mould growth because of combination of 1. Defective/undersized fans 2. turning off fans at isolation switches 3. stuffed/closed vents 4. vents in window frame (behind curtains) 5. poor maintenance 6. poor thermal performance 7. clothes drying in Living Rooms 8. high humidity cooking 9. high humidity firewood 10. recirculation kitchen fans …and now • high levels of insulation (U) • poor thermal bridging detailing (fRSi) • high levels of airtightness (AP)
  7. 7. Natural Ventilation (NV) – issues 1. Differential pressure which is not consistent 2. Behavioural - Block up wall and window inlets 3. Overwhelming evidence to show natural ventilation (NV) under-ventilates (refer Scottish study, 2014) 4. Studies showing CO2, humidity, VOCs high with Natural Ventilation to current standards 5. Part L 2018 refers to a maximum of 5 m3/m2/h to reduce heat loss but industry is easily achieving 1.5 m3/m2/h @ no cost …or even 0.8 m3/m2/h* Tip: *site management quality control and detailing (sequencing and tolerances)
  8. 8. Definition of comfortable healthy buildings Evidence has shown that the optimum environment humans feel comfortable in  18-21 degrees Celsius is the optimum temperature  45-55% humidity (>65% unhealthy)  400-600 ppm carbon dioxide levels (>900 ppm unhealthy) …and whole house designed systems helps to get you there
  9. 9. Solutions 2 types System Mechanical Extract Ventilation (MEV) Mechanical Ventilation Heat Recovery (MVHR ) Basic description - supply Humidity controlled continuous air supply at same temp as outside Humidity controlled continuous air supply at same temp as inside Basic description - exhaust Humidity controlled continuous extract Humidity controlled continuous extract Part F compliance Specifically stated Specifically stated
  10. 10. 2 Types of DCV and HRV systems Decentralised dMEV - see sample Centralised cMEV - see sample Decentralised dMVHR - see sample Centralised cMVHR -see sample Fans 3 1 7 1 Ducts No ducts Extract ducts only No ducts Supply and Return Fan Type Layout
  11. 11. Comparison DCV v HRV Criteria dMEV cMEV dMVHR cMVHR Ducts No ducts Extract ducts only No ducts Supply and Return Cost - S and I (excl VAT) €1800 – 2 bed €2000 - 3 bed €1800 – 2 bed €2000 - 3 bed €4000 – 2 bed €4500 - 3 bed €4000 – 2 bed €4500 - 3 bed Temperature at inlet Same as outside Same as outside *Just below that of the house *Just below that of the house Integrated remote monitoring No No No Yes DEAP input No No No ? Yes Impact on heating cost None assessed None assessed €100/annum ? €100/annum ? Basic characteristics affecting key decisions on social housing – 2 bed @ 85 sqm and 3 bed @ 100 sqm
  12. 12. 2 Types : d = Decentralised and c = Centralised Type dMEV cMEV dMVHR cMVHR Ducts No ducts Extract ducts only No ducts Supply and Return Fans – 2 bed 85 sqm 3 nr 1 nr 6 nr 1 nr Noise at supply grill Dishwasher = 55dBA Fridge = 42dBA Whisper = 30 dBA Rural Nighttime = 25dBA None • 11 dBA extract* • 35 dBA boost * *@1m None • 20 dBA fan • 35 dBA boost 11 dBA * * @1m and prog to OFF for night time 23 dBA* • 26 dBA fan • 45 dBA boost* * @1m and prog to 10- 15dB for night time Filters Yes No Yes Yes Air Permeability (door undercut) Lowest possible Lowest possible (6-10mm) 1.5 m3/m2/hr (4-10mm) 1.5 m3/m2/hr Maintenance Washable filter/yr Wash valve + fan/2 yrs Washable filter/yr Vacuum /3mths + Replace filter/yr + Service/2yr Fan location 154mm dia. pipe to wetrooms Store or attic 154mm dia. pipe in walls Store or attic Cost to run ++ €5/yr €30/yr €40/yr €70/yr Impact on useable floor space No Yes 0.04 sqm + fan No Yes 0.5 sqm + fan ++ Dependent on usage (number of showers, drying clothes etc)
  13. 13. Impact on space – cMEV in Rathdrum 2 housing project for Wicklow County Council Project House Nr. Ventilation Type Reason(s) Rathdrum 20 cMEV Ensure compliance Kilbride 42 cMVHR 1. Concerns tenants blocking up vents 2. Remote monitoring
  14. 14. Impact on space – cMEV in Rathdrum Fan in attic Vertical extract riser Vertical extract riser High level boxing out
  15. 15. Impact on space – cHRV- 3 methods 1. Localised boxing out 2. Dropped ceiling 3. Integrated with ‘Easijoists’
  16. 16. WSN (Wireless Sensor Networks) Measures • Temperature - 0C • Humidity - % • Carbon dioxide - ppm • Noise - dBA
  17. 17. Few Interesting Side Points • Decentralised suits retrofits (as no ductwork ). Note: Watch AP • Social housing may require attic fans to be caged and isolation switches to be hidden • MEV and MVHR works with closed stoves i.e. provided it has its own air supply …so does not work with open fireplaces • Kitchen extract is always separate • Use a fire collar when penetrating a fire rated enclosure • Integrated systems - can’t turn off ventilation system separately …If you were designing your own home which one would you choose ? dMEV or cMEV or dMVHR or cMVHR
  18. 18. Y factor
  19. 19. WSNs Tip: Energy Show April 18th and 19th This would never have happened if COADY were the ER My dad said the reason I am falling asleep in class is because of the levels of CO2 in the classroom. Averaged last week 2043ppm alone! My mum said that my asthma is getting worse because of the levels of humidity averaged over 72% and CO2 averaged over 1956ppm last month in the classroom Miss I cant concentrate because it is 15.3 degrees in here . Can we close the windows ?
  20. 20. Thankyou Q and A NOTICE - Buildings are your homes and your communities, and you have a responsibility to ensure that they are built in compliance with the “Building Regulations” which provide for sustainability, safety and health and welfare of people in and around buildings