Satisfying 2008 Regs wrt Renewables

MicktheMan

Hi Folks,
I know there's not a lot of activity in the new build sector at the moment but I was wondering what is being specified to satisfy the renewable element of the 2008 part L regs. I would like to see what different configurations are been specified in order to comply, what are the main issues etc. Tia.

PJMCKE

Hi Mick the man,

I just had my pre BEr completed and found it facinating and a little flawed. The 10Kw from renewables is easily made if you are using a renewable source as a primary heating and water heating.
I spent over an hour with my BEr assessor and found that HRV had neagtive effect on the calculations and where I had primary space and water being oil and a wood pellet boiler stove it failed to meet the requirements of 10Kw. This is beacuse oil was taken are primary and wood pellet boilerstove contribution was deemed as secondary and therefore only 10% of its contribution was actually taken into account. Taking the previous sentance I needed 24m2 of solar to meet 10 Kw.
I had spend so much on the fabric of the house and getting a 3000 sq ft house down to under 15kW of energy required to heat it that I am finding the extra expence of supplying 10Kw of renewables to heat the house hard to swallow. It really should be a percentage of required demand rather than a flat rate of 10Kw. Does this mean that passive builders have to over spec their house.
I would love to hear from BER essessors as some items in the software were not tangable. Unfortunately I can't recal the exact detail as I was selecting alot of different options and permutations but literally both of us queried the results.

My current options (I have excluded geothermal and for the moment wind power)

wood pellet stove with intergated boiler (15k Kw). Would meet requirement. HRV,No oil. I had also included 6 M2 of solar
or
Oil/pellet stove with boiler with 24 m2 of solar (not practical/possible)
or
wood gassyfying/combi boiler (pellet/wood/grain).

I am still at infancy stage but in the next few weeks I hope to have this sorted and can report back to you hopefully with something more intellegent to ad..
I am open to PM from interested parties on pellet boiler stoves pellet boilers/ gassyfying boilers and options. I hope this does not infract in anyway with the mods.

MicktheMan

PJ thanks for your reply.

You raise the exact issues I was inferring and are the reasons for starting the thread. I would also like to get input from other ber assessors and designers on what they are specifying to comply.

For instance, if a wood burning stove (room heater only, not pellet) is being specified for secondary heating along with solar, what type of stove is allowed. I understand (or at least have heard) that you can get wood only burning stoves that will take logs/timber but if you put other fuel into them, such as coal, the heat exchanger will clog and you effectively "brake" the stove. I have asked the DoE for guidance but as yet have not got a reply.

You are correct. The renewable requirement does not take any account of the build specification wrt airtightness and insulation and is, imo, severly flawed. Imo a 10% renewable contribution would be a much more intelligent way of forming the regulation. This would then encourage the better specification in build fabric etc. From an economic point of view, the current regs dissuade people from spending the extra money on better insulation and airtightness (aiming for passive or near passive). Surely the best form of renewable energy is to not to have to use the energy in the first place!

Well done on your build spec (15kW/m2/yr) ... this is imo, where the powers that be should be encouraging people to achieve ... not 24m2 of solar.

Also, as an aside, I do not accept that a heat pump is a "renewable" source especially given the fact that the primary energy source is > 90% fossil fuel generated and the performance is so dependent on design, installation and build quality, workmanship etc, given the fact that we are so good in this country wrt building standards :rolleyes:.

Mick

saibhne

PJMCKE wrote: »

Hi Mick the man,

Taking the previous sentance I needed 24m2 of solar to meet 10 Kw.
I had spend so much on the fabric of the house and getting a 3000 sq ft house down to under 15kW of energy required to heat it that I am finding the extra expence of supplying 10Kw of renewables to heat the house hard to swallow. It really should be a percentage of required demand rather than a flat rate of 10Kw. Does this mean that passive builders have to over spec their house.

I'm wondering if something has been misinterpreted here.. The obligation is to provide 10 kWhrs (not kW..) of thermal renewable energy, per m2 of your house, a year. For example if you have a 100m2 floor area house you would need to provide 1000kWhrs of renewable thermal energy a year.

Your house is about 280m2 so you need to supply approx 2800 kWhrs of renewable energy a year. In terms of solar thermal water heating a rule of thumb is that each m2 of solar panel will provide about 500Kwhrs per year. Your requirement should be supplied by a fairly modest system of about 6 - 8 m2 of panel



See this link for some more info:
http://constructireland.ie/Articles/Part-L-Building-Regulations/Examining-the-key-changes-in-Irelands-new-energy-standard/Page-4.html

sydthebeat

PJMCKE wrote: »

The 10Kw from renewables is easily made if you are using a renewable source as a primary heating and water heating.

a renewable source that does primary and water heating would constitute a passive build

PJMCKE wrote: »

I spent over an hour with my BEr assessor and found that HRV had neagtive effect on the calculations and where I had primary space and water being oil and a wood pellet boiler stove it failed to meet the requirements of 10Kw. This is beacuse oil was taken are primary and wood pellet boilerstove contribution was deemed as secondary and therefore only 10% of its contribution was actually taken into account.

the primary heating system is basically the system that can heat the largest part of the house. A wood stove, in the majority of cases, will not be the primary source if there is an oil boiler specified. If the wood stove is to be the primary heating source, it should be sized as such, and teh oil boiler should have less output that it.

PJMCKE wrote: »

It really should be a percentage of required demand rather than a flat rate of 10Kw. Does this mean that passive builders have to over spec their house.

i agree that its flawed. It would be a foolish certifier that would refuse to accept a passive certificate and demand parl l compliance. However, if no cert is applied for and received, then the build is NOT passive and building reg compliance should be demanded.

Regarding the hrv not having a positive effect.

for HRV to have a positive effect in DEAP,
1. air tightness should be good (IMHO <5)
2. do not use default values, get your assessor to search SAP appendix Q
3. make sure flue / chimney inputs are correct

PJMCKE

I want to put some information up here that I recieved recently to the board memeber to comment on. I previously posted a preliminary BER calculations with respect to DEAP. I contacted another BER assessor who had queried the 10kw/m2 contribition with their local authority and my initial BER calculations had dismissed the fact that I put in a pellet stove in the build and only used 10% of its actual contribution. Below is the reply I got back regarding this..

I wolud like for any Ber accessors to comment as it makes renewable contributions for part L much easier.

According to the Building Control officer here in Mayo as long as the product can supply 10kw/m²/a from a renewable source only, it adheres to the regulations, whether it is primary or secondary is irrelevant. It however cannot be a wood burning stove for instance, as this would also be able to burn turf etc. but a wood pellet stove is fine. The only place they look for conformity with deap (for renewables) is with solar, you would have to get the 10kw on DEAP for that. They do use DEAP to check conformity for the regs in relation to U value calculations for your walls etc.



So yes, ignore DEAP for your pellet stove. You will have to supply the manufacturers declaration to prove that the stove is capable of contributing the required amount. But that is easy enough.[/COLOR][/COLOR]

Leadership

PJMCKE wrote: »

It however cannot be a wood burning stove for instance, as this would also be able to burn turf etc. but a wood pellet stove is fine. The only place they look for conformity with deap (for renewables) is with solar, you would have to get the 10kw on DEAP for that.

This is hillarious, so my woodburning stove with a back boiler plus planting 2 acres of trees will not count.

sydthebeat

DEAP has to make certain assumptions in order to be able to compare buildings of similar size. It does not calculate based on specific usage.

A wood burning stove CAN and WILL be counted as renewable once it is certified as a 'dedicated' wood burning stove. These are available of the maket, check stockton stovax.

A stove that can burn turf coal etc is not considered as a renewable heating source for OBVIOUS reasons.

The difference between primary and secondary heating systems in DEAP are clear.

"The primary or main heating system is that which heats the largest proportion of dwelling. It is a heating system which is not usually based on individual room heaters (although it can be), and often provides hot water as well as space heating. Main heating systems are categorised on the basis of generic types in Tables 4a and 4b. Occasionally there may be two central heating systems, for example two separate boilers used to heat different parts of the property. In this case the calculation should be undertaken using the system that heats the largest part of the property.

In DEAP a main space heating and main water heating system (and associated fuel for each) must be specified at all times.

The secondary heating system is based upon a room heater. Secondary heating systems are taken from the room heaters section of Table 4a .
A secondary heating system is to be specified if:
a)
the main system is not sufficient in itself to heat the dwelling to the temperatures on which the DEAP is based
or
b)
fixed secondary heaters are present (e.g. a gas fire, a chimney and hearth capable of supporting an open fire or a solid fuel stove). "

Therefore if there are two systems, say a wood burning stove in the living room and a oil burner external, the primary source is one with the largest output. It doesn't matter if the persons using the house do not turn on the oil and continuously burn wood, because "The DEAP calculation is based on the characteristics of the dwelling and the systems installed and not on the heating practices of the occupying household".

If the two systems are equal in range and output, then the cheapest fuel source is chose as the primary.

From DEAP calculations i have done, having a wood burning stove as secondary heating source (assumed to give 10% of heating energy) does not usually meet renewable requirement of 10kwhr/m2/yr.

sydthebeat

PJMCKE wrote: »

It however cannot be a wood burning stove for instance, as this would also be able to burn turf etc. but a wood pellet stove is fine

see above.

a stove that burns wood and turf / coal is just a stove.

a wood burning stove must be dedicated to wood alone.

PJMCKE

Hi,
I think some of the details were taken up and some missed on the previous post.
It is correct that a multifuel stove does not qualify. More importantly that the 10kw/m2 contribution of renewables is irrespective of the DEAP software calculations. Well this is at least from the enforcement officer in our local council. This does make it significently easier to make this contribution. Maybe my initial thoughts could be srcutinized a little more here

Example.
I had previously hoped to use a oil burner with a pellet stove and also there was a wood burning sotve only. If the pellet stove had a contribuition of 7-9kw and the wood burning stove was calculated to be so that both made the 10kw/m2 contribution. In the eyes of building control I have met with the contribution requirements. But in the DEAP software the pellet stove would only be 10% of its contribution and I would not meet the building requirements. Is this correct.

sydthebeat

PJMCKE wrote: »

More importantly that the 10kw/m2 contribution of renewables is irrespective of the DEAP software calculations.

absolutely not.... compliance with Part L regs can ONLY be shown by DEAP calculations.

PJMCKE wrote: »

I had previously hoped to use a oil burner with a pellet stove and also there was a wood burning sotve only. If the pellet stove had a contribuition of 7-9kw and the wood burning stove was calculated to be so that both made the 10kw/m2 contribution. In the eyes of building control I have met with the contribution requirements.

If both can be calculated to show they make the 10kwhr/m2/yr requirement then great, however, the approved methodology to show this calculations is the DEAP methodology. In DEAP the secondary heating system is clearly dealt with in that
"Table 7 gives the fraction of the heating that is assumed to be supplied by the secondary system. The treatment of secondary systems is not affected by any control options for the secondary system"

Table 7 states all secondary systems provide 0.10 (10%) of energy.

Therefore, in the example you gave, if both the pellet stove and the 'dedicated' wood burning stove provide adequate output to heat both the space and water, then they can be considered the 'primary' system and the oil can be considered the secondary system.
However, if they cannot, they should be inputed as the secondary system offering 10% of the energy. See paragraph C.3 of TGD L

badolepuddytat

I looked at this for several dwellings.

As discussed by a prev. poster, if biomass is the main heating fuel, then this is a non issue.

If the house is modest, then solar will meet the 10 kWh/m2/annum. i.e. less than 150m2.

As the dwelling gets larger, the yield is harder to reach with solar, as you will not be using all of the extra DHW generated in the peak months, therefore in dwellings over about (I say about, as it's all modelled on panels and slopes etc) 200-250m2, solar will be more difficult to meet the target 10 kWh/m2/annum.

If you have fossil based main heating and you need to add a bit more to your solar: If you add Wood burning stove (either pellet or certified wood burning only) it will supply 10% of the heat load. This is where it gets tricky, as if the house is say 15kWh/m2/annum, then this will only be 1.5kWh/m2/annum in DEAP. So Very large, Very low energy requirements, a fossil fuel main system main not be applicable.

So In essence the 10kWh/m2/annum is saying: build a small house, solar is ok on it's own, build a large house, you will need to supply primary with a Renewable main heating source.

Heat pumps with a COP over 2.7 are allowed treat each kWh over the 2.7 as RES for the puroposes of DEAP.

PJMCKE

badolepuddytat Thanks for that information. I am building a 2995 sq ft house and came to the same conclusion that my main heating system must be from a renewable source and have decided to go with a pellet boiler.

SYDTHEBEAT. I have sent your comment on to the BER assessor who forwarded on the comment to me originally to ignore the DEAP calculation. Hopefully this will clarify that the enforcement officer was incorrect or the interpretation taken from the BER assessor was incorrect.
This has proven quite difficult as it appears that all are not on the same wavelength with respect to part L.

sydthebeat

PJMCKE wrote: »

SYDTHEBEAT. I have sent your comment on to the BER assessor who forwarded on the comment to me originally to ignore the DEAP calculation. Hopefully this will clarify that the enforcement officer was incorrect or the interpretation taken from the BER assessor was incorrect.
This has proven quite difficult as it appears that all are not on the same wavelength with respect to part L.

its not at all unusual for a building control officer toi have his / her own views as to the interpretations of the regs. The DOEHLG usually wash their hands of responsibly by advising someone with a query to contact their local BC officer.

to the assessor who said "ignore the DEAP calculations"...
is he your certifier???
if you saw the DEAP software you will see that the results page clearly indicates whether Part L compliance has been met or not....

see here for example...

the area circled in read clearly shows whether teh specification complies with the renewable requirement of Part L

the areas circled green also show other aspects of Part L that have to be met in order to comply......namely, min window u values, min elemental u values, energy performance coefficient and carbon performance coefficient....