Fulfilling Part L idea

Mazotasan

I have been investigating how to fulfill part L of the regs in relation to the renewable element recently. Basically we are investing in the building envelope in terms of u value/performance, air tightness and insulation etc. We will install a HRV and a sealed room stove. The heating system is an efficient condensing boiler and rads (due to budget... would've tended towards ground source HP). To fulfill part L I now seemed to be kinda backed into the corner of installing solar panels which I think are still just too expensive...I then got the idea of possibly installing a small say 3-4KW air source HP for heating the domestic hot water only...anyone tried this or foresee any issues with it or have other solutions...

RVR

Only problem i can see with this idea is that for part L only the part of the energy produced over a COP of 2.5 can be allowed towards the 10kwh/m2.

http://www.environ.ie/en/Publications/DevelopmentandHousing/BuildingStandards/FileDownLoad,19069,en.pdf - Section 1.2.3

Because of this would probably be difficult to meet the 10kwh/m2 when doing DHW only.

Solar is still probably your best option but if you install a large enough wood stove with back boiler it might do you instead. Call around the suppliers again, there has probably been plenty of price drops for the new year...

al2009

would installing an air to air heat pump qualify, a 5KW unit for example?

Alec

Jimbo

How about installing a wood-only burning stove as the secondary space heating source?

You would need to check on DEAP that it provides the 10kwh/m2 (secondary space heaters can only provide 10% of the heating required when installed with a boiler)

sinnerboy

+1

You need DEAP calcs to show compliance with Part L for

Energy
Renewables
CO2 emissions

It cannot be guessed - it must be demonstrated by calculation

So holding on to that thought - you also must have a BER cert issued prior to occupation . Which will require .... DEAP calculations

So the smart thing to do is use the BER process to inform the design not just confirm the build at completion

quentingargan

Mazotasan wrote: »

I have been investigating how to fulfill part L of the regs in relation to the renewable element recently. .....To fulfill part L I now seemed to be kinda backed into the corner of installing solar panels which I think are still just too expensive...

I'm sort of surprised that people find solar too expensive on a new house. As RVR suggested, prices have dropped if you shop around.

Retrofitting is a lot more costly, and still deemed to be worthwhile by many. But on a new house which is particularly well insulated as yours is, solar may be particularly appropriate. On a conventional house, when the central heting is running, is almost casually heats the domestic hot water on its way to the radiators, but if your central heating is off for 8 months of the year, you are either using an immersion, or using the boiler, heating up boiler, flue and pipework to the cylinder just to heat the hot water which is somewhat more inefficient.

It won't cost much more to use a solar cylinder with a twin coil while you are fitting a cylinder anyhow (especially if the domestic hot water system is unvented), the panels you require to meet part L and a pump station won't cost much, and if you use flatplates before you roof, it is no more work than sticking in a couple of velux windows. Your system, if properly installed, should be trouble free for 40 years. Compared to retrofitting where you have to change an existing cylinder and scaffold, remove slates etc., its a breeze!

sydthebeat

It is a flaw of part L 2008 that the renewable requirement is based on a per sq m rate rather than a percentage of energy demand, but i suppose thats because per sq m is a definite value while energy demand is mainly down to user practises.

quentingargan

sydthebeat wrote: »

It is a flaw of part L 2008 that the renewable requirement is based on a per sq m rate rather than a percentage of energy demand, but i suppose thats because per sq m is a definite value while energy demand is mainly down to user practises.

A spin off of this is the assumption that more people live in your average 250 sq m house than in a 150 sq m one, with an almost pro-rata requirement for more hot water. (My experience is quite the opposite with DINKYs in big houses, dishwashers etc., and less hot water use). :rolleyes:

sydthebeat

quentingargan wrote: »

A spin off of this is the assumption that more people live in your average 250 sq m house than in a 150 sq m one, with an almost pro-rata requirement for more hot water. (My experience is quite the opposite with DINKYs in big houses, dishwashers etc., and less hot water use). :rolleyes:

sort of agree,

this is also borne out when considering social housing design.

typically 3 bed 100 sqm dwellings are designed for a 6 person occupancy. 7 person dwelling is typically 110 sq m. !!!

however, DEAP assumes to a maximum occupancy of 7 persons. (i think remember seeing that in the old xls spreadsheet model)

gizmo555

quentingargan wrote: »

Retrofitting is a lot more costly, and still deemed to be worthwhile by many.

There's a grant available for retrofitting, which isn't for the OP's new house.

The big difference between (almost*) every other energy efficiency measure and solar hot water is that except for solar they all add to the comfort of the house as well as saving energy. On the assumption that one can get all the hot water one needs one way or another, whether it be from oil, electricity or solar, a solar system adds nothing to the comfort of a house.

OP, I agree with you, solar is still too expensive for what you get. If I was in your shoes I'd go for the wood stove, which has the advantage of providing a backup heat source to your boiler, in case of running out of oil, power cuts, etc., as well as providing some of your heating from a renewable source.

(*I guess CFL bulbs don't add much to comfort levels either )

ccsolar

gizmo555 wrote: »

There's a grant available for retrofitting, which isn't for the OP's new house.

The big difference between (almost*) every other energy efficiency measure and solar hot water is that except for solar they all add to the comfort of the house as well as saving energy. On the assumption that one can get all the hot water one needs one way or another, whether it be from oil, electricity or solar, a solar system adds nothing to the comfort of a house.

OP, I agree with you, solar is still too expensive for what you get. If I was in your shoes I'd go for the wood stove, which has the advantage of providing a backup heat source to your boiler, in case of running out of oil, power cuts, etc., as well as providing some of your heating from a renewable source.

(*I guess CFL bulbs don't add much to comfort levels either )

Sorry Gizmo555

I have to agree with quentin
Solar has got very cheap over the last year, you just have to shop around especially if you are building a new house.
Regardless what system is installed you will need a DHW tank.
Fit a triple coil tank and connect a wood burning stove for extra saving while it heats your house, before you fit a heat pump you should consider the cost of running it.


CC

gizmo555

ccsolar wrote: »

Sorry Gizmo555

I have to agree with quentin
Solar has got very cheap over the last year, you just have to shop around especially if you are building a new house.

How cheap?

ccsolar wrote: »

Regardless what system is installed you will need a DHW tank.

Ain't necessarily so. A combi boiler will heat water on demand, doing away with the need for a hot water tank. It also has the benefits that you only heat exactly the amount of hot water you need and you never run out of hot water. The OP has mentioned planning to install a condensing oil boiler, this option should at least be considered.

ccsolar

gizmo555 wrote: »

How cheap?

Hi Gizmo

Can't say how cheap sydthebeat is watching.

Ain't necessarily so. A combi boiler will heat water on demand, doing away with the need for a hot water tank. It also has the benefits that you only heat exactly the amount of hot water you need and you never run out of hot water.


Question
What heats the water in the combi boiler?

CC

gizmo555

ccsolar wrote: »

What heats the water in the combi boiler?

CC

Oil or gas.

Combination boilers are capable of providing instant hot water and heating while saving space within a home.

The conventional arrangement in Ireland is to have a normal boiler which heats the radiators via a sealed water circuit. By “sealed” it is meant that the water is contained within the system, going around in a loop between the radiators and the boiler.

To heat the “domestic hot water” (i.e. the water that comes out of the hot taps) the storage cylinder in the hot press has a coil in it through which the “radiator water” flows.

The disadvantage with this arrangement is that if the cylinder does not have hot water in it you have to wait some time for the coil to heat it up.

A ‘combi’ boiler is a boiler which combines both a conventional boiler for radiators and an independent water heater, together in the one unit. This dispenses with the hot water cylinder in the hotpress. But better still, it means that hot water is always available instantly and for as long as you need it.

http://www.sei.ie/Power_of_One/Heat_Your_Home_For_Less/Replacing_Your_Boiler/

ccsolar

Hi Gizmo555
I know what you are saying Gizmo but OIL or GAS is getting expensive the SUN is always FREE therefore SOLAR will always be the cheapest.
I know that you will always need oil or gas as a back up but a solar system will reduce your water heating cost.
My point is that solar is the cheapest form of renewable energy.

CC

gizmo555

ccsolar wrote: »

I know what you are saying Gizmo but OIL or GAS is getting expensive

Bord Gáis Energy today (6th January 2010) welcomed the approval by the Commission for Energy Regulation (CER) of its proposed reduction to the price of gas by an average 8% for Residential and SME sectors from 1st February 2010. This will be the third gas price reduction in less than a year – giving a cumulative decrease of over 25% since May 2009.

http://www.bordgais.ie/corporate/index.jsp?1nID=93&2nID=95&nID=761&aID=1820

ccsolar wrote: »

the SUN is always FREE therefore SOLAR will always be the cheapest.

My point is that solar is the cheapest form of renewable energy.

If you ignore the initial capital cost. You claim it's reducing but won't name a figure. I agree with the OP that it's still too expensive to allow the capital cost to be recovered in a reasonable period.

ccsolar

Gizmo555
I will PM you a figure as the moderator will not allow here.
In my opeinion bord Gais is dropping its prices because of the amount of people leaving them.

CC

gizmo555

ccsolar wrote: »

In my opeinion bord Gais is dropping its prices because of the amount of people leaving them.

Bord Gais doesn't set its own prices, the energy regulator does. Part of the regulator's role is to prevent Bord Gais and the ESB from exploiting their dominant positions by temporarily setting prices too low in order to price competitors out of the market. I'm not too sure about gas, but there has been much criticism of the regulator for having the perverse effect of keeping electricity too high, in order to facilitate competition.

quentingargan

ccsolar wrote: »

Gizmo555
I will PM you a figure as the moderator will not allow here.
In my opeinion bord Gais is dropping its prices because of the amount of people leaving them.

CC

For the short to medium term it looks like both gas and electricty prices are going to continue to fall, and the reason is supply and demand in the gas sector generally. Prices spiked last year because supply is limited - the recession quickly fixed that.

Against that trend, it becomes more difficult to sell all renewable energy systems - the price reductions in installation and supply are being offset (roughly) by falls in prices.

But when (if?) this recession ends, energy demand will again rise and prices will soar, simply because we have reached global peak production of oil (and peak gas isn't far behind, with or without Corrib).

In that situation it is sensible to include some wood burning option in a well insulated house, but I personally would still fit a cylinder suitable for solar (3-coil if solid fuel is on the cards) and bite the bullet because the grant isn't there for any house built after June 2008, so retroftting later will not have the benefit of any form of assistance.

That said, some households use very little hot water (modest showers, dishwasher plumbed to cold etc) so I agree it ain't for everyone.

Mazotasan

Many thanks for feedback/opinions. Currently collecting data on different systems and then will sit with my BER guy to run the maths. I will shop around for solar prices again as it was 4 months ago since I delved into it...they probably have come down in price. I don't have the perfect alignment for solar either so was losing a few % points in terms of efficiency, but still even with alignment for best efficiency the panels (4 months ago) would've needed to be 50% cheaper to compare with the small heat pump, now that was looking at dhw only and hadn't taken into consideration the 10kwh/m2. The other thing I really must do is understand how exactly we are going to use hot water, in general its probably most often taken for granted that it just comes from the hot tap!

gizmo555

Mazotasan wrote: »

The other thing I really must do is understand how exactly we are going to use hot water, in general its probably most often taken for granted that it just comes from the hot tap!

This is a very important point. A reasonable rule of thumb is that washing machines and dishwashers account for about 20% of hot water use in a typical household. Almost without exception these days, such appliances are supplied with cold water only inlets, which means the hot water they use can never be supplied by solar.

A decently specified solar h/w system is reckoned in Irish conditions to provide about 60% of annual hot water demand. This means leaving out hot water used by appliances, at best solar is likely to supply less than half of annual hot water needs.

quentingargan

gizmo555 wrote: »

A reasonable rule of thumb is that washing machines and dishwashers account for about 20% of hot water use in a typical household. Almost without exception these days, such appliances are supplied with cold water only inlets, which means the hot water they use can never be supplied by solar.

Agree here and even when you go to the trouble of buying a hot and cold feed washing machine as we did, on a 40 degree wash it uses cold only, and on a 60 degree wash it uses both hot and cold. I guess this is to prevent hot water from the system causing colours to run.

We have a short hose attached to the tap in our utility room and fill the machine through the detergent drawer from the hot tap, then switch it on for a 40 degree wash. The machine detects that the water is already above 40 degrees and works away. When you do this, the amount of electricity used by the machine for a full was falls to les than 1/2 of what it would otherwise be. Of course, if you are using an immersion heater, that is a wasted exercise, but if you have a cylinder full of hot water from either solar or a stove, it makes perfect sense.

But I recently came across a solar business with a very high pressure sales pitch that sold a (very expensive) system to pensioners who had electric showers and used virtually no hot water. If you are going to have solar hot water, ideally you woudn't install electric showers etc.

ccsolar

gizmo555 wrote: »

This is a very important point. A reasonable rule of thumb is that washing machines and dishwashers account for about 20% of hot water use in a typical household. Almost without exception these days, such appliances are supplied with cold water only inlets, which means the hot water they use can never be supplied by solar.

A decently specified solar h/w system is reckoned in Irish conditions to provide about 60% of annual hot water demand. This means leaving out hot water used by appliances, at best solar is likely to supply less than half of annual hot water needs.

Hi
I have connected the cold inlet from my dishwasher to the hot supply and it works perfect, the dishwasher never has to heat the water, wouldnt recommend this idea for a washing machine.
I have heard that some appliance manufacturers are going back to the old 2 pipe system.

CC

gizmo555

ccsolar wrote: »

Hi
I have connected the cold inlet from my dishwasher to the hot supply and it works perfect, the dishwasher never has to heat the water, wouldnt recommend this idea for a washing machine.
I have heard that some appliance manufacturers are going back to the old 2 pipe system.

CC

You're absolutely right, you can do this, but for most people it will be of little or no real benefit.

If you connect the dishwasher to a hot supply it will very likely have filled itself before any hot water arrives at the connection. At my kitchen sink, right next to my dishwasher, about 3 to 4 litres of cold water have to be run off before hot water starts to flow. Coincidentally, this is about the same amount as my dishwasher uses in each wash & rinse cycle! This is precisely the reason why manufacturers stopped supplying these appliances with hot & cold feeds.

There was a poster in another thread here who described his solar setup in which his hot water cylinder was in his utility room very close to the appliances which used hot water. If that's done, solar may make worthwhile savings in this area, but not otherwise. Of course, a combi boiler sited in a utility room could be used in the same way.

Also, the pre-wash and interim rinse cycles on dishwashers use cold water. Switching to a hot water only supply means these cycles will be done with hot water too. It won't do any harm to the dishes, but outside of the couple of months a year when solar may provide 100% of hot water needs, it wastes energy.

Naux

I'm inclined to agree that solar is still too expensive. I have found that 4.5 to 5k is the price that I've seen quoted by most around Galway. 300 litre tank with 5sqm panels. I think thats too expensive.

ccsolar

Hi Naux
It depends on what type panels you were getting,
Were they integrated flat plate/ on roof flat plate or tube?
It does seem a bit expensive.
Can you PM me details of what you got for that price?

CC

quentingargan

Naux wrote: »

I'm inclined to agree that solar is still too expensive. I have found that 4.5 to 5k is the price that I've seen quoted by most around Galway. 300 litre tank with 5sqm panels. I think thats too expensive.

In relation to payback times, it really depends on your perspective. If a system costing €4,500 saves you €300 to €350 per year, a payback time of 15 years is equivalent to a simple return on investment of 6.7%. However, it is generally accepted that energy inflation will be higher than other inflation over the long term (not the short term) and it is not unreasonable to expect that ROI to increase to 10% during the life of the product.

Some solar companies promise 5 year payback on systems. That creates unrealistic expectations for renewable energy in general. To my mind, if mortgage rates are less than 6%, and the ROI is above 6%, and you're saving energy, reducing CO2 emissions etc., it makes sense:).

Don't know if that is an installed price or not. If it is installed, then for roof integrated panels it is in the ballpark. If not, shop around. I personally wouldn't install the cheaper surface mounted flat plate panels, particularly in the west of Ireland for wind-load reasons (and aesthetics).

Solar installation should no longer be seen as a single speciality in the case of new-builds. Roofers can and should do the roof work as part of their stock in trade, and plumbers fit cylinders and a good many plumbing contractors have at least one plumber who is qualified for solar.

If you are doing this work during construction, getting the roofers to put in the panels shouldn't add to their costs much - its basically the same as a few extra Velux windows. You have to fit a cylinder anyhow, and fitting a solar one is not any more expensive if you are using a pressurised system. After that, a pump station, flexible pipework and the other bits and bobs are a few hundred euro. The plumber, assuming they are already trained on solar, should be able to do the rest in half a day.

If I were you, I'd shop around for hardware rather than installed systems and make sure your builder is willing to install. Q

gizmo555

quentingargan wrote: »

In relation to payback times, it really depends on your perspective. If a system costing €4,500 saves you €300 to €350 per year, a payback time of 15 years is equivalent to a simple return on investment of 6.7%. However, it is generally accepted that energy inflation will be higher than other inflation over the long term (not the short term) and it is not unreasonable to expect that ROI to increase to 10% during the life of the product.

Some solar companies promise 5 year payback on systems. That creates unrealistic expectations for renewable energy in general. To my mind, if mortgage rates are less than 6%, and the ROI is above 6%, and you're saving energy, reducing CO2 emissions etc., it makes sense:).

Without wanting to rehash all the previous debates we've had on this topic, Quentin, I think we can both agree that €300 to €350 p.a. is at the very highest end of achievable savings at current energy prices. This payback estimate also assumes that there is no change in hot water usage patterns over the 15 years, which is highly unlikely.

As for whether it is reasonable to expect energy prices to increase at a greater rate than inflation generally, there is certainly greater volatility in energy prices, but in the long run energy is such a big component of other costs that it would be just as reasonable to expect them to increase at around the same rate.

One thing which is certain is that mortgage rates have only one direction to go at present and that is up. For a home builder who is adding the price of a solar system to his mortgage, the interest costs must be deducted from gross savings before arriving at a nett savings rate. If one takes this into account, payback periods would be far beyond the 15 years you mention.