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Buying a house-BER-airtightness and other questions?

  • #1
    Moderators, Sports Moderators Posts: 11,473 mod Vegeta


    Hey folks,

    Last year I was looking to build my own house but after a lot of site searching and going round and round in dead end circles myself and the girlfriend decided to buy.

    So we have a deposit on a 3 bedroom, 2 storey, semi-D 1410sqft. Its in an estate which received grants from SEI to spend on the houses.

    So the house is supposedly air tight, has extra insulation, has HRV and a sealed increased efficiency fire unit instead of a fire place.

    So my questions are as follows (apologies for my n00bness)
    Are we entitled to receive a BER from the contractor, as in, if I ask for one does he have to give one to me.

    How will I know just how air tight the house is, can I request an air tightness report from him and again does he have to provide me with one. Also they have recently just cut 2 holes to the exterior, through the utility wall for the exhaust pipe of the gas burner. So how should they be sealed. if all goes to all, how much am I looking at to get this done myself? 2000-2500

    I assume if the house is not very air tight this will negatively effect the HRV system, will this cause the system to use more electricity or end up costing me more money in electricity bills?

    Is there anything I should be looking out for with the systems above when going to snag the house? Any general tips you have for me.

    One of the reasons we chose the house is because it has the above features which will hopefully will make it a bit cheaper to run fuel bill wise so a big concern I have is that they will not be working correctly and will only be installed half arsed.

    Any help gratefully appreciated.


«1

Comments



  • Vegeta wrote: »
    So my questions are as follows (apologies for my n00bness)
    Are we entitled to receive a BER from the contractor, as in, if I ask for one does he have to give one to me.

    After Jan 01 2009 - yes . Before then no .
    Vegeta wrote: »
    How will I know just how air tight the house is, can I request an air tightness report from him and again does he have to provide me with one.

    No not ever - but in this climate - he will probably let you have the test report
    Vegeta wrote: »
    Also they have recently just cut 2 holes to the exterior, through the utility wall for the exhaust pipe of the gas burner. So how should they be sealed.

    Quick set mortar most likely - make sure they DO do it
    Vegeta wrote: »
    I assume if the house is not very air tight this will negatively effect the HRV system, will this cause the system to use more electricity or end up costing me more money in electricity bills?


    Big question . Rule of thumb- Q50 - 5 is max "leakage" for HRV to works well . ( 5m3 max of air should should pass through the external envelope in one hour at Pascall 50 - i.e storm pressure ) . If Q50 is greater than 5 then yes - you could loose heat not recover it . Ask for the SAP Appendix Q ratings . Hope to get effecieny rating of 80% + Specific fan powers: down to 0.50 W/l/s

    http://www.sap-appendixq.org.uk/searchresults.jsp?parentID=1&categoryID=3&bestPracticeCompliantID=&companyID=&productSearch=&performance1ID=&performance2ID=&performance3ID=&Submit=Search

    Vegeta wrote: »
    Is there anything I should be looking out for with the systems above when going to snag the house? Any general tips you have for me.

    look here

    http://www.boards.ie/vbulletin/showthread.php?t=2055385732
    Vegeta wrote: »
    One of the reasons we chose the house is because it has the above features which will hopefully will make it a bit cheaper to run fuel bill wise so a big concern I have is that they will not be working correctly and will only be installed half arsed.

    Caveat emptor
    Vegeta wrote: »
    Any help gratefully appreciated.

    My very best wishes - good luck :)

    .




  • Good post sinnerboy. Just about covers everything.




  • sinnerboy wrote: »
    Big question . Rule of thumb- Q50 - 5 is max "leakage" for HRV to works well . ( 5m3 max of air should should pass through the external envelope in one hour at Pascall 50 - i.e storm pressure ) . If Q50 is greater than 5 then yes - you could loose heat not recover it . Ask for the SAP Appendix Q ratings . Hope to get effecieny rating of 80% + Specific fan powers: down to 0.50 W/l/s

    http://www.sap-appendixq.org.uk/searchresults.jsp?parentID=1&categoryID=3&bestPracticeCompliantID=&companyID=&productSearch=&performance1ID=&performance2ID=&performance3ID=&Submit=Search

    .

    Thanks sinnerboy, after reading the info you gave me I feel much better equipped to ask some questions of the contractor

    caveat emptor, aint that the truth. My cousin has a house in the same estate and he asked none of this stuff.

    I am not too worried about the BER but I do want to know if the HRV system is going to actually work for us. Also thanks for the heads up on the fire hazard.

    I read that thread but didn't see this stated plainly, do they have to connect the HRV to the smoke alarms?




  • Vegeta wrote: »
    I read that thread but didn't see this stated plainly, do they have to connect the HRV to the smoke alarms?

    Yes - and fit all outlets / inlets with dampers to close over in the event of a fire Word to the wise - be prepared to insist on this . The HRV industry is generally NOT on top of this




  • sinnerboy wrote: »
    Yes - and fit all outlets / inlets with dampers to close over in the event of a fire Word to the wise - be prepared to insist on this . The HRV industry is generally NOT on top of this

    Cool so I am after the results of the air tightness test and need to ask about the HRV being connected to the alarm and the outlets/inlets

    When you say outlets/inlets do you mean to each room or just the ones to the outside of the house?

    If they don't have this done, is there any building code I can reference when dealing with them?


    Thanks again sinnerboy, this is some valuable info, you're an asset to the site.


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  • Vegeta wrote: »
    When you say outlets/inlets do you mean to each room .

    yes
    Vegeta wrote: »
    or just the ones to the outside of the house?

    no - not required here - UNLESS - smoke would block your escape from fire - in other words if these vent points were right beside front / rear doorway .

    Be prepared for a fight - to be considered "flaky" . The industry is in denial But don't back down on it .

    This is a message received from a colleague ....

    I was just onto an MHRV company and asked them if they were aware of the issue/request before. This is their answer:

    “No, but I have since found out insurance companies exploit holes in plasterboard eg down lighters starting fires, to reneg on claims.”

    Many houses (particularly those that are newly refurbished or low energy) do not have the fire protection the householders need and the Regs require, ....Industry including suppliers are not focused on this fire risk and insurance companies know this




  • SEI house of Tomorrow schemes had a requirement for permeability of less than 10 m3(hr/m2)@ 50 pascals pressure difference, tested on each house type not each house. This Q50 value is the UK standard and is an expression of the flow due to leakage in m3per hr divided by the envelope area. It is less accurate than the EU measure of Air changes per hour where the volume is compared to leakage flow rate over a given time @ 50 pa. ACH air changes per hour is called the n50 value. n50 = q50 x surface area, divided by volume. A n50 of 10 could typically have a q50 of 8.5. This method eliminates abnormal results due to complex designs with large surface areas.

    A result at or above [email protected] is a leaky house. With MHRV a value of [email protected] would be an upper limit. Passive houses require 0.6ACH @ 50 pa. I tested a house on site this week that exceeded 0.2 ach @50pa.




  • Retro-Fit wrote: »
    I tested a house on site this week that exceeded 0.2 ach @50pa.

    Wow - what steps did they take to achieve that RF ?

    The "cut off" point Q50/n50 can vary depending on where you seek guidance
    BSRIA report BG 4/2006 cites Q50 /5 as normal practice , Q50/3 as Best Practice ..... but I am not arguing with you

    I would say that even with a test result of 5 , the delivery of air quality to the OP , even if not at optimal energy efficiency , would be worthwhile




  • Retro-Fit wrote: »
    SEI house of Tomorrow schemes had a requirement for permeability of less than 10 m3(hr/m2)@ 50 pascals pressure difference, tested on each house type not each house. This Q50 value is the UK standard and is an expression of the flow due to leakage in m3per hr divided by the envelope area. It is less accurate than the EU measure of Air changes per hour where the volume is compared to leakage flow rate over a given time @ 50 pa. ACH air changes per hour is called the n50 value. n50 = q50 x surface area, divided by volume. A n50 of 10 could typically have a q50 of 8.5. This method eliminates abnormal results due to complex designs with large surface areas.

    A result at or above [email protected] is a leaky house. With MHRV a value of [email protected] would be an upper limit. Passive houses require 0.6ACH @ 50 pa. I tested a house on site this week that exceeded 0.2 ach @50pa.

    0.2 ach??????

    Thats savage!

    I tested a house just under 1.0 ach and I was in a house last week that claims a 0.5 ach but 0.2 ach, thats excellent.

    Timber frame/SIP panel I assume?




  • Retro-Fit wrote: »
    A result at or above [email protected] is a leaky house. With MHRV a value of [email protected] would be an upper limit. Passive houses require 0.6ACH @ 50 pa. I tested a house on site this week that exceeded 0.2 ach @50pa.

    What do you mean by upper limit, as in there is no point in having the MHRV if the house is at or above [email protected] or roughly 2.5m3/hr/[email protected] (using the 10 to 8.5 example above)

    I really really doubt the house will be that air tight, I don't know I just don't have confidence that it will be (I'm a pessimist). Would be surprised if its 5m3/hr/[email protected] let alone 3m3/hr/[email protected]

    So the first step is to ask for the results (which will be interesting, they may not have done it at all, I have seen a blower door in one of the other houses though (different type house))

    Once I get the results all I can do is judge whether they are good enough or not. After that I'm not sure what to do.

    So if the house has a poor air tightness result what would you folks advise me to do?


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  • Doctors differ - patients die

    I say 5 is a reasonable cut - off

    There is a tendency for some to take a view "if it's not A rated or passive house standard - it's no good " . I differ from that .

    context from SEI

    2195 certs issued - mostly B's

    Energy
    Rating % Ratings
    A1 0.05%
    A2 0.14%
    A3 7.47%
    B1 18.38%
    B2 40.06%
    B3 24.42%
    C1 7.01%
    C2 1.25%
    C3 0.46%
    D1 0.60%
    D2 0.14%
    E1 0.00%
    E2 0.00%
    F 0.00%
    G 0.00%

    There are 3 PHI certified passive houses in Ireland now . One is not for sale but these 2 are
    http://constructireland.ie/Vol-4-Issue-2/Articles/Passive-Housing/Carlow-houses-show-how-to-beat-the-passive-standard.html
    Yes there are are many more that claim ( possibly genuinely ) to achieve PHI standard. I don't know what that number is but it won't be a big number

    Most of us live in houses drawn from the existing stock and most of us will continue to do so, for some time to come- there are 75,000 unsold units out there. It is the existing stock from which most of will have to choose .

    So Vexorg , unless you want to track down a passive house ( certified or otherwise ) or build one yourself you must place your potential choice in context .




  • Vegeta wrote: »
    So if the house has a poor air tightness result what would you folks advise me to do?

    Get it fixed before you buy . There are pointers here

    http://constructireland.ie/Articles/Passive-Housing/Are-energy-ratings-letting-down-passive-houses/Page-3.html




  • This weeks results of 0.2 and 0.5 [EMAIL="[email protected]"]ach50pa[/EMAIL] were both on passive houses, one closed and one open panel timber frame, both had diffusion open materials, the latter used no membranes. The former was a builders own house and he spent all week taping over the screws that hold the vapour check in place. (It was a standard geotex vapour check not the facy stuff) He put about 20 hours into improving the integrity of the inner membrane and reduced from 0.47 to 0.21 pressurised. The other house has only its external skin on, when it is insulated and lined it will exceed 0.1 i'm sure.

    Last week I also air tested part of a house that was set for demolition because 'it was going to be impossible to make it habitable by today's standards'. It had hollow block and single glazed windows, built in the 70's with evidence of mould growth on some walls. It Pased with less than 10m3(hr/m2). The good practice figures of 5-10 ach are out of date and are appropriate for 1970's buildings where carbon monoxide and radon dilution were issues. In a modern low energy building, I'd be dissapointed to be over 2 ach and would think there was a problem if it exceded 3. A balanced MV system needs to be balanced with a slight overpressure on the supply side, to ensure exhaust of pollutants, leaks in the fabric affect the dynamics of the airflow.

    Air tightness needs to be designed in from the start, a bolt on solution will lead to gaps in the continuity of air barrier at wall/floor junctions and building services trades will not puncture the barrier at will.

    Archie.




  • HI SINNER ET AL -

    House of tomorrow scheme set quite stringent targets for developers to achieve before they got the grant - INCLUDING.......

    A pressure test....should achieve an air permeability of less than 3m3/h/m2 at 50Pa......

    I seem to recall a retro test of a large number of HOT granted houses - and only one achieved the target! - but all got the grant anyway.

    I would say that a lot of the failures had MVHR put into them as well!

    I'd like to see the certificate myself.




  • Can someone explain this to me in a more simplier form ([email protected] )

    Any links to what it means....Total noob, but interesting reading...

    Thanks




  • Hia Mad

    1m3/m2/hr -

    1 cubic metre of air (3ftx3ftx3ft) passing THROUGH each square metre of your building fabric (walls - floor - roof - windows - and doors) every HOUR when your house has been pressurised to Q50 (It's only a measurment of pressure - air pumped into the house normally thru' the front door - if you where inside you wouldn't even notice - no ear popping or anything!)

    BUILDING REGULATIONS is 10m3/m2/hr - I've been told it's a hole the size of 1 Euro coin in EVERY metre of fabric - sounds easy to achieve - but in reality many fail.

    Go below 4 or 5 and it is recommended that MECHANICAL VENTILATION is installed.

    Wet finishing inside and keeping a reasonable eye on holes will achieve about a 7 typically.




  • ardara1 wrote: »
    Hia Mad

    1m3/m2/hr -

    1 cubic metre of air (3ftx3ftx3ft) passing THROUGH each square metre of your building fabric (walls - floor - roof - windows - and doors) every HOUR when your house has been pressurised to Q50 (It's only a measurment of pressure - air pumped into the house normally thru' the front door - if you where inside you wouldn't even notice - no ear popping or anything!)

    BUILDING REGULATIONS is 10m3/m2/hr - I've been told it's a hole the size of 1 Euro coin in EVERY metre of fabric - sounds easy to achieve - but in reality many fail.

    Go below 4 or 5 and it is recommended that MECHANICAL VENTILATION is installed.

    Wet finishing inside and keeping a reasonable eye on holes will achieve about a 7 typically.

    Many thanks for that,

    What exactly do you mean (Wet Finishing) So the lower the number the better?




  • ardara1 wrote: »
    Go below 4 or 5 and it is recommended that MECHANICAL VENTILATION is installed.

    Wet finishing inside and keeping a reasonable eye on holes will achieve about a 7 typically.

    Draft TGD F 2008 - requires if you go below Q50 - 7 then background ventilation ( holes in walls ) requirements must be increased by 50%

    At the "lions" seminar tonight - advice was was "cut off" point - i.e. degree of air tightness ( or looseness :D ) past which you should NOT use HRV is Q50 7 . I'm sticking with 5




  • sinnerboy wrote: »
    Draft TGD F 2008 - requires if you go below Q50 - 7 then background ventilation ( holes in walls ) requirements must be increased by 50%

    At the "lions" seminar tonight - advice was was "cut off" point - i.e. degree of air tightness ( or looseness :D ) past which you should NOT use HRV is Q50 7 . I'm sticking with 5

    Hi Sinner - hope the lions didn't bite! - Blowing fresh air into a leaky house is like blowing air into a sieve - it's actually reduces efficiency (Run it thru' DEAP) you'll blow any nice warm air outa' the house.

    (I'll pass on the reference for the 5 cut off later)




  • sinnerboy wrote: »
    At the "lions" seminar tonight - advice was was "cut off" point - i.e. degree of air tightness ( or looseness :D ) past which you should NOT use HRV is Q50 7 . I'm sticking with 5
    Was it worthwhile showing up for? Might go to one next month if theres any useful info coming out of it (other than the usual sales blurb).


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  • Sinner - the Number 5


    Good Building Guide GBG268 from the EST
    Energy efficient ventilation in dwellings – a guide for specifiers


    MVHR
    These systems can provide the ideal ventilation
    system, delivering the required ventilation rate
    almost independently of the weather conditions.
    However, the energy saving benefits are only
    realised for airtight properties (<5m3/hr/m2 at 50Pa)
    when almost all ventilation air passes through the
    heat exchanger.




  • Thanks Ardara1

    300m2 B1 one off - skim through stats here
    conventional build
    Walls 0.18 w/m2k
    Gd floor 0.13 w/m2k
    roof 0.13 w/m2k
    windows - default 2.1 w/m2k
    A grade condensing gas boiler ( SH + DHW )
    Zoned heating
    6m2 solar
    75% LEL
    Y factor 0.11
    Assumed Q50 7 AT
    No open fires - 75% efficient gas , room sealed for SHS
    Hole in wall nat vent

    Result B1 - 79 - 16

    If I enter
    HRV - SAP AP Q 80% / 0.5 ( and omit holes in walls )

    Result A3 - 74 - 14

    If I change Q50 - 10 AT

    Result B1 - 79 - 16 i.e. if I meet b regs min for AT - HRV does nothing for energy efficiency - but it does not make things worse either

    If I change Q50 - 5

    Result A3 - 69 - 14 - Q50 - 5 "works"

    If I change Q50 - 3

    Result A3 - 65 - 13 - Q50 -3 is better - of course

    If I change Q50 - 12 - i.e. if I don't meet reg min for AT

    Result B1 - 85 - 17
    HRV is loosing energy




  • sinnerboy wrote: »
    Thanks Ardara1

    300m2 B1 one off - skim through stats here
    conventional build
    Walls 0.18 w/m2k
    Gd floor 0.13 w/m2k
    roof 0.13 w/m2k
    windows - default 2.1 w/m2k
    A grade condensing gas boiler ( SH + DHW )
    Zoned heating
    6m2 solar
    75% LEL
    Y factor 0.11
    Assumed Q50 7 AT
    No open fires - 75% efficient gas , room sealed for SHS
    Hole in wall nat vent

    Result B1 - 79 - 16

    If I enter
    HRV - SAP AP Q 80% / 0.5 ( and omit holes in walls )

    Result A3 - 74 - 14

    If I change Q50 - 10 AT

    Result B1 - 79 - 16 i.e. if I meet b regs min for AT - HRV does nothing for energy efficiency - but it does not make things worse either

    If I change Q50 - 5

    Result A3 - 69 - 14 - Q50 - 5 "works"

    If I change Q50 - 3

    Result A3 - 65 - 13 - Q50 -3 is better - of course

    If I change Q50 - 12 - i.e. if I don't meet reg min for AT

    Result B1 - 85 - 17
    HRV is loosing energy

    Tends to lend towards the 5 theory rather than the 7? perhaps they sell more systems at a 7!

    My nerdy bit now - Y-value of 0.11 or 0.15 - needs to bew 0.15 for post July.
    I would argue that at a wall U-value of 0.18 - even the accredited details won't work - need to go enhanced and line internally.




  • y = 0.11 for new dwellings whose details conform with guidance given in Building Regulations Technical Guidance Document (TGD) L (including references) or are shown to be equivalent. A default value of y = 0.15 applies otherwise.


    80 XT in cavity + 25+12 XT CPB internal




  • SB how do you get 80mm into cavity. is the residual cavity reduced to 30mm or have you increased the cavity to 120mm. If so ehat wall ties are you using as standard SS ties only stretch to 110mm.




  • sinnerboy wrote: »
    y = 0.11 for new dwellings whose details conform with guidance given in Building Regulations Technical Guidance Document (TGD) L (including references) or are shown to be equivalent. A default value of y = 0.15 applies otherwise.


    80 XT in cavity + 25+12 XT CPB internal

    Sinner - 2007 Part L -

    1.3.3.3 The DEAP calculation of primary energy
    use and CO2 emissions (see Section 1.1) takes
    account of thermal bridging effects. In general this is
    done by including an allowance for additional heat
    loss due to thermal bridging, expressed as a
    multiplier applied to the total exposed surface area.
    Where provision for thermal bridging is made in
    accordance with options (a) or (b) of Paragraph
    1.3.3.2, (“Limiting Thermal
    Bridging and Air Infiltration – Acceptable
    Construction Details)_this multiplier should be taken as 0.08.
    Where option (c) of Paragraph 1.3.3.2 is used - (Use alternative details which limit the risk of
    mould growth and surface condensation to an
    acceptable level), it will
    be necessary to allow for each thermal bridge
    separately in the calculation. Alternatively a
    multiplier of 0.15 may be used.


    Only 2 options here

    See your calcs - throw in 0.04 and see what happens




  • topcatcbr wrote: »
    SB how do you get 80mm into cavity. is the residual cavity reduced to 30mm or have you increased the cavity to 120mm. If so ehat wall ties are you using as standard SS ties only stretch to 110mm.

    residual cavity 40mm . there is an engineer appointed - don't have spec to hand - sorry




  • ardara1 wrote: »
    Sinner - 2007 Part L -

    1.3.3.3 The DEAP calculation of primary energy
    use and CO2 emissions (see Section 1.1) takes
    account of thermal bridging effects. In general this is
    done by including an allowance for additional heat
    loss due to thermal bridging, expressed as a
    multiplier applied to the total exposed surface area.
    Where provision for thermal bridging is made in
    accordance with options (a) or (b) of Paragraph
    1.3.3.2, (“Limiting Thermal
    Bridging and Air Infiltration – Acceptable
    Construction Details)_this multiplier should be taken as 0.08.
    Where option (c) of Paragraph 1.3.3.2 is used - (Use alternative details which limit the risk of
    mould growth and surface condensation to an
    acceptable level), it will
    be necessary to allow for each thermal bridge
    separately in the calculation. Alternatively a
    multiplier of 0.15 may be used.


    Only 2 options here

    See your calcs - throw in 0.04 and see what happens

    Thanks A1

    TGDL 05 applies - completion is expected soon . TGDL 05 does not in itself provide for a global Y factor .

    My cut and paste is from the latest DEAP manual - it refers back to TGD L 05 which in turn refers to Homebond ROTS and UK Robust Details .

    I have implemented UK Accredited Details . To be signed off . As I read it - I won't even need this for BER as TGDL 08 is not applicable

    So - I am sticking with 0.11

    Will look at 0.04 later

    By the way - anyone else feel dizzy with the endless flow of Regs that dont meld well ?




  • Ok folks, just a quick update

    I was in looking at the kitchen in my house today to make sure everything was done according to our specs.

    Our developer is on holidays (our usual point of contact) so I mentioned it to the site foreman in passing about the AT results and he said as far as he knows it was 3 ach. Now I am not sure if that house type was tested and got a 3 ach result or if my exact house was tested. Will find out for definite when developer is back from holidays and we go snagging and stuff like that.

    Now here's the bad news. He said the MHRV was NOT connected to the smoke detectors. It seems someone else has asked those questions already too as he said "We've been through this already and its not required by the regulations"

    Now this was a casual friendly conversation with the foreman so I didn't probe or push too far.

    So my question now is:

    Are there Irish building regulations which state that MHRV has to be connected to the smoke alarms/detectors?

    I'd like to know this before I go pushing back on them. Thanks folks


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  • Vegeta wrote: »

    Are there Irish building regulations which state that MHRV has to be connected to the smoke alarms/detectors?


    No .

    So what ?

    Put your foot down

    Insist all the outlets are fitted with fire dampers too

    Good news on the AT . 3 is quite good

    .


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