Major Renovations - Bldg Regs 2019

descol

Hi out there

Looking at what triggers definition of Major Renovation of existing buildings- I would appreciate advice / direction.

Say, in the case of a two storey terrace house - Walls to be upgraded with internal insulation, new windows / ext doors and attic insulation- floor to remain - New condensing gas boiler and rads etc

My understanding is that the total area of the heat loss elements is established i.e floor/walls/windows/doors/and roof - say this area is 350 sqm

If the external walls are to be upgrade with internal insulation and the area is - say 100sqm - then the calculation is:

100 sqm divided by 350 sqm - giving 28.5%

As this % is more than 25% of the total - this triggers the requirements to comply with 2019 Bldg Regs i.e upgrade to B2 ? or is it B3 ?

Am I correct in this thinking ?

Also - there appears to be an opt out ? element - related to cost optimal calculations

Has any one out there gone down the cost optimal path maybe via a consultants ?

Thoughts welcome
thanks
Descol

Calahonda52

at least 25% =>B2, IIRC opt out is only if it is technically, functionally and economically not feasible

sydthebeat

you have the "triggering major renovations aspect correct"

in most cases the major renovation works will bring you to a B2 level anyway... ie as in your example... upgraded walls, ceilings, windows, doors, condensing boiler and controls should bring you to B2 in the majority of cases.

where it doesnt bring you to B2 for whatever reason (ie your main heating system is electric storage!)you can then look at the 'cost optimal' works to be compliant...
however if you look at your example then its actually the same works proposed ie external walls and windows renovation >25% requires ceiling insulation, and boiler change to condensing

its not exactly an "opt out" option as in you can do less work..... but just another way of counting the works that you have to do as acceptable

descol

thanks Cal/Syd

So, in the example of the terrace undergoing a major renovation - am I correct in thinking that the upgrade works will also need to meet the Bldg Reg requirements associated with MPEPC/MPCPC - which may mean solar and or photovoltaic installation works - ?
descol

sydthebeat

descol wrote: »

thanks Cal/Syd

So, in the example of the terrace undergoing a major renovation - am I correct in thinking that the upgrade works will also need to meet the Bldg Reg requirements associated with MPEPC/MPCPC - which may mean solar and or photovoltaic installation works - ?
descol

no

these are existing buildings, so the DEAP (BER) assessment is done as an "existing building" based on the year of construction.... so its not done as a new building under 2019 regs

therefore once you reach a B2 rating, in accordance with the age band of the house, then you comply.

There is no MPEPC or MPCPC in "existing buildings"

does that make sense?

descol

Yes Syd - that seems sensible - and as such I would not expect to see an Architect's Opinion / Certificate stating compliance with current Bldg. Regs ?
Descol

sydthebeat

descol wrote: »

Yes Syd - that seems sensible - and as such I would not expect to see an Architect's Opinion / Certificate stating compliance with current Bldg. Regs ?
Descol

nope ill disagree on that

works are always subject to building regulations which are applicable at time of works.

NZEB for major renovation is current building regulations, therefore any cert will have to refer to current Part L 2019 regulations.

I think youre mixing up the requirements for a new build, versus the requirements for a renovation / extension.

As the 2019 regs is the first reg to bring extensions into DEAP, and the fact that DEAP cannot assess extensions / renovations independently of the whole structure, that mix up is very understandable.

However you just have to look at compliance as the outcome of the DEAP assessment (B2 or better), rather than the particular individual inputs that got to that outcome.

descol

Syd - Thanks for your helpful thinking