Mechanical engineer

Effects

Hi, I'm looking for some advice regarding appointment of mechanical engineer.
Out architect recommended we needed an electrical and also a mechanical engineer for our building project. It's a two bed house in dublin city, 100 Sq M.
After speaking with a builder friend he said he didn't think we needed a M.E. for such a small project. Another architect friend agrees.
Out architect says we do need one, and that he's also needed to do our deap calculations.
Can anyone offer advice on this? We are keen to save anywhere we can. Neighbours objections have cost us a lot extra so far and eating into our budget. The delay due to having to apply to ammend original permission granted has pushed out timeline back with added result of subcontractors prices increasing.

I should also add, we've already agreed that we don't need an electrical engineer for the project.

Metric Tensor

You do need someone to do the DEAP calculation - this is mandatory. Some architects offer this as part of their service - others don't. There's plenty of people out there offering this as a stand-alone service too. Some are excellent - some are pure sh*t. Make sure you check them out before hiring them.

To get the gold standard of heating/plumbing design you would need to hire a competent professional to design and detail it (this means a Mechanical Engineer). In many domestic cases a combination or subset of: Client / Architect (or other professional) / DEAP professional / Contractor / Plumber / Supplier carry out the "design" of the mechanical (heating and plumbing) works. The outcome from this set up is closely linked to the quality, skill, experience and vested interests of the parties involved.

If your architect is advising you to employ a mechanical engineer he may have strong and sound reasons to do so. You should ask what they are. There may be complexities involved in the project that would only be appropriately addressed by a suitable expert.

BryanF

Imo it's the Mvhr that pushes the need for a mechanical engineer as there are so many Cowboys out there

Calahonda52

Metric Tensor wrote: »

...
If your architect is advising you to employ a mechanical engineer he may have strong and sound reasons to do so. You should ask what they are. There may be complexities involved in the project that would only be appropriately addressed by a suitable expert....

Or he may, I suspect, just be getting more experts, at your expense, to underwrite the different risk aspects of the project.

Without giving too much away, what are the mech features that point to an M.E.?
As MT has suggested, go ask, in writing.

In addition if u do get an M.E, will the associated PI be available directly to you or only via the architect?

The other, unrelated to your post, question, is what A/T target have you set?
What insulation targets have you set?

Min building regs or near Passiv, or zero carbon, or net positive energy?

Metric Tensor

Calahonda52 wrote: »

Or he may, I suspect, just be getting more experts, at your expense, to underwrite the different risk aspects of the project.

Excellently phrased CH - I was trying to include that point in my write up but I don't have the magic with words that you do!

BryanF's point re MHRV is very good too. I was living in the past and forgot the MHRV. It's done so wrongly so often!

Effects

Thanks for all the replies. Lots of great information here. I had assumed from early meetings with our architect that the DEAP calculations were going to be done by him. Perhaps he meant that it was going to be done, but by a separate professional. I can understand that perhaps he isn't fully knowledgeable on the different systems and calculations for them.

During meetings he has hinted at wanting a combi boiler to save space on a cylinder. I've been against this for a couple of reasons.
We had initially wanted a stove with back boiler to heat rads and cylinder. We have access to turf and a decent amount of firewood, while also planting 6 acres of new wood land this year. We are now thinking of just a stove to be a space heater on our open plan living level on the first floor. Leaving a gas boiler to heat the rads on the ground floor in a zoned system.

Our planning allows for solar PV on the roof. I've heard mixed reviews on their efficiency though. As there is no feed in tariff at the moment, I still want the cylinder so that we can divert the power from the PV to heat the water when it's not being used elsewhere. I understand we can't mention this in our DEAP calculations.

The architect has also said he doesn't think we need to go as far as MVHR but just a mechanically vented system without the heat recovery.
I've spoken with a builder friend who's working on a project at the moment who has put in a system of MVHR in the wet zones only with passive vents in the other areas. It has quite a low air tightness target.

As of yet I can't remember exactly what AT or BER target we are aiming for but I'll find out. I'm presuming the higher a rating you want the more it costs and our budget is tight anyway. I take it that the minimum now is still quite good, and we'll aim higher than that anyway. I'll also ask what mech features are pointing him to a ME.

The quote from the engineer is as follows:
GREEN BUILD ADVISORY REPORT: €800
MECHANICAL SERVICES DRAWINGS & SPECIFICATIONS: €850
SITE INSPECTIONS AND FINAL CERTIFICATION: €250 per inspection (3 or 4 needed)
FINAL BER: €200

Originally the mech and elec services, drawing and spec were €600 higher but we dropped the electrical as myself and a colleague are looking after it. I'm a qualified sparks, he's a registered electrical contractor.

Metric Tensor

You'll be both surprised and disappointed by how restrictive the DEAP calculation will be on your propsed heating methodologies. You should get it done really soon before you make too many plans.

Two comments:
1. MHVR extracts air from the wet rooms and pumps air into the living areas. I have never seen or heard of a whole house MHRV system that "only" works in the wet areas. Is your builder friend talking about a number of small "one room only" MHRV units with one in each wet room? Either way from my point of view MHRV is not in my opinion totally necessary provided your are installing a mechanical ventilation system of some type - again the DEAP will throw up some interesting results on this.
2. I don't what a "Green Build Advisory Report" is. Make sure that a "Preliminary DEAP Calculation" discussed with you and revised/adjusted as necessary to meet your requirements is included in the report.

Effects

So the DEAP calculation might restrict me in the way I want to heat my house?
I presume then that mechanical ventilation of some kind is definitely needed?

The breakdown of the Green Build Report as follows:

Our Green Build Advisory Report is a site specific report detailing the materials and services to be employed during
the construction of the extension and the refurbishment of the existing dwelling in order to achieve compliance with
Part L building regulations and to ensure that the house will be a comfortable and economical building to live in.
As part of this service we will carry out a Provisional Building Energy Rating (BER) to determine the extent of energy
related materials required to achieve our Client’s target BER, e.g. B2, B1, A3, etc. The report will contain
performance specifications for floor, wall and roof insulations as well as window and door thermal, light and solar
specification.
A feasibility study will be carried out to determine the most suitable and efficient space and hot water heating
system. In addition to the heating system, we will also examine other energy saving systems and provide our
recommendations as to their suitability for this particular property, e.g. rainwater harvesting, photovoltaic panels,
mechanical ventilation heat recovery system, etc.

Calahonda52

OP:
re this: I take it that the minimum now is still quite good

If you mean the minimum as per Part L, then you are seriously mistaken.

Effects

Calahonda52 wrote: »

OP:
re this: I take it that the minimum now is still quite good

If you mean the minimum as per Part L, then you are seriously mistaken.

Then I'm seriously mistaken! I had thought that insulation regs for new builds would be quite high right now. I guess not!
What sort of rating should I be aiming for? Or is it a case of as high as we can afford?

I'm waiting on a response from the architect regarding target BER rating he has in mind.

sydthebeat

Calahonda52 wrote: »

Or he may, I suspect, just be getting more experts, at your expense, to underwrite the different risk aspects of the project.

this, in a nut shell, is probably whats happening.

Architect doesnt want to (not confident enough to) take the risk of certifying compliance with building regulations in relation to mechanical services.

and that 'green build report' sounds like a DEAP report with some green trimmings. (id be worried that they are calling it a "provisional BER" because its certainly not a provisional BER.... )

Metric Tensor

Calahonda52 wrote: »

OP:
re this: I take it that the minimum now is still quite good

If you mean the minimum as per Part L, then you are seriously mistaken.

I agree with CH if he is talking about the Part L backstop values but IMO the CPC and EPC requirements for new build force people to have a house spec that is "quite" good. For any expense you go to to lift the house beyond this level (which usually equates to about A3) it is important to carry out your own cost/payback analysis.

TBH I have found the majority of clients have their budget stretched to get to this level.

OP - is this a new house or extension? I had assumed new house but it says "extension" above. It's an important difference!

Calahonda52

[This is to supplement/compliment/flesh out what MT and STB have written: it is trying to get you to understand whats at issue here as the owner]

While the BER is a planning requirement it lacks the necessary detail, accuracy and scientific methodology to tell YOU, how energy efficient YOUR house is going to be so its not the thing to either focus on or, more importantly be blindsided by/ fobbed off with.

There are two concepts you need to understand here.
One is the U value of the different aspects of the design, the attached are from a Leaving Cert Book. [copyright acknowledged]

The first link is for details, second for Irish pricing
https://www.amazon.co.uk/Construction-Technology-Designing-Sustainable-Homes/dp/0717148343/ref=sr_1_fkmr1_1?ie=UTF8&qid=1463079029&sr=8-1-fkmr1&keywords=construction+technology-+trevor+hockey

https://schoolbooks365.ie/index.php?_route_=construction_technology_hickey

You need to get these values from your man, don't show him this, just ask for the U values.

The second aspect is the Airtightness layer and how this is being achieved.

The A/T design is more important than the U Value because the best U values in the world won't be worth a damn if the A/T is crap..
Go get the leaving cert book, best 40 euro you will ever spend.

Metric Tensor

P.S. - agree completely re not concentrating on the BER result once you have achieved the necessary levels for compliance.

Effects

Metric Tensor wrote: »

OP - is this a new house or extension? I had assumed new house but it says "extension" above. It's an important difference!

It's a new house. I presume it's a copy and paste error!

Effects

Calahonda52 wrote: »

Go get the leaving cert book, best 40 euro you will ever spend.

I'll pick up that book. My only problem is if it'll slow down the tender process while I try and figure it out.

I've some understanding on U values. I studied engineering in DIT and covered this in one of the modules. Haven't used it since so quite rusty on it.

Calahonda52

Maybe get one for the architect as well..LOL

It wont slow you down all as it has a raft of simple pictures in it to go with the text which will give you lots of help with the tender.
If you rush/black-box the tender prep then you will not get the right result.

Chapter 19, pages 236 to 262 has just diagrams of details for TGDL 2011 and Passiv Haus.

Its like ikea instructions, prominently pictures, without the help line icon.

Effects

Calahonda52 wrote: »

If you rush/black-box the tender prep then you will not get the right result.

We are just trying to make up for lost time. Neighbours cost us about 8 months when we had to reapply to have our permission amended.

Calahonda52

Proceed with haste, regret at your leisure.

A few days to get it right may save you thousands over lifetime of the house
A few days not to get it right will cost you thousands over lifetime of the house.

Your beloved BER
(E2-A1) is (340-25) kWhr/m2/yr
so
315*100*0.20 = €6,300 per annum.

Maybe my figures are a bit extreme but not the message.