The life & times of an HVAC Engineer











{March 14, 2011}   You know you’re a geek when…

My husband and I are currently trying to buy our first house together, so we spent this weekend looking at houses. By the end of the weekend we’d chosen the house we’ll hopefully manage to buy and we’d discovered that we truly are construction & energy geeks.

Whilst the estate agent showed us around, pointing out the ‘delightful neutral décor’ or the ‘brand new carpets’ or occasionally, at their peril, a room that ‘would be perfect as a nursery’ James and I were ferreting around checking the energy performance and pondering what energy-efficient upgrades we could make.

Of course the compulsory energy performance certificates (EPCs) are a big help these days, they let you know all the basic details about standards of construction, insulation and heating. They also tell you a few areas you could make improvements in, for example a fairly standard EPC comment is ‘install energy efficient light bulbs’. But EPCs are intended for the general public to understand and be able to act on…they wont give you the full potential of what could be achieved.

So, with heads stuck in loft space, peering through ventilation bricks and stomping over gardens we discussed a variety of ‘new’ technologies we’d consider installing in any of the 1930-1950’s houses we were looking at. A couple of our favourites were:

– A ground source heat pump coupled with underfloor heating. This would reduce the energy bills, and by using this heat we could actually gain money from the Renewable Heat Incentive. It would also mean we wouldn’t need any radiators so we’d gain floor/wall space, and they’re something rather lovely about pottering around barefoot on a heated floor in my opinion.


– A mechanical heat recovery ventilation unit, these draw hot, humid air from areas like kitchens and bathrooms and use it to heat fresh air from outside before delivering it to other rooms like bedrooms and lounges. Most houses lose heat through bathroom fans and kitchen extract hoods, and many houses have no fresh supply except through leakage which reduces as we install better doors and windows. People need oxygen to live and generally 8-12 litres of fresh air per second is recommended to be supplied to occupied rooms in order to keep people feeling awake and comfortable. So, instead of losing the heat from the kitchen, we would be re-using that heat whilst still getting nice fresh air into the building, like this:

With so many ideas bouncing round in our heads we can hardly wait to get into a new house and start saving energy!

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kayels says:

You know, I’ve seen these kind of systems on Grand Designs but it never occurred to me that it could be done on existing, normal houses. It’s a great idea and I hope you find the perfect house soon so you can get on with your plans!



Chloe Agg says:

Well finding somewhere for the ductwork that isn’t too conspicuous might be a challenge…but since I plan ductwork routes for a living I ought to be able to figure something out! The units themselves though are pretty small so will fit in most loft spaces.

Laying underfloor heating in an existing home does mean ripping all the floors up and pouring concrete or laying insulation between the joists, so it’s not a simple job…but it’s something I’d love to do.

I’ll have to let you know how it goes!



Sarah D says:

back in the day my Dad’s lecturer put one in his garden and got permafrost after a while- good job you know a ground expert. What’s the orientation like- you could go for the feed in tariff at the same time and power the pump with PV…



geekchloe says:

Well we’ve not managed to buy one yet, but the one that we’re looking at faces east, so there’s no south facing roof. However, there is a flat roofed garage at the end of the garden with no houses creating shadow, so we could put panels on that and install them at an angle. Many things to contemplate once we’ve bought somewhere I think. The feed in tariffs and renewable heat incentive certainly make all these things even more appealing.

You’re right about the potential for permafrost if you do things badly…but if we can’t manage to get a ground source heat pump correctly installed with our qualifications & experience (mechanical engineering, building services, geology, geotechnical engineering and environmental management between the two of us) then we should probably quit our jobs!



Firesparx says:

Just stumbled upon your blog today, glad to find another woman in the HVAC engineering world!

My husband and I just built a house and we designed it to be super energy efficient (Energy Star rated here in Canada). I’m an HVAC engineer and my husband is a mechanical engineer so we had to pick a contractor that would put up with our nerdiness. While many women would be researching paint colours and flooring choices I was reading up on the latest building science and of course residential heating and cooling options (which is frustratingly limited when you are used to working with commercial/industrial HVAC units). We settled on a ground source heat pump with forced air and a heat recovery ventilator. However, I still have dedicated exhaust fans in the bathrooms. I didn’t like the idea of the humid air being pulled into the HRV, potentially causing mold on the core and shortening the life of the unit. I also don’t think exhausts through HRVs have a high enough capture velocity to efficiently remove moist air from bathrooms. So my HRV is only responsible for supplying tempered fresh air to the house, it leaves the exhaust work to the dedicated fans.



geekchloe says:

Hi there,
I’m glad you found me then, and I hope you still enjoy the blog while I’m on my sojourn away from building services. You certainly get treated very differently by contractors, mechanics etc in your home life when they find out what you are in your personal life don’t you? And yes, it can be very difficult to find the level of detail on domestic heating & cooling that we would expect to be reading if it were an industrial application. It’s not something I’ve had to deal with too much yet as having only just bought our house we now have no money to spend on it (and building one is a rarer feat over here – there isn’t much land that you’re allowed to self-build on), but I’m sure I will do. I hadn’t thought about the mold issues from the damp air…it seems such a shame to loose the heat that gets built up in bathrooms, but I can very much see your thinking on that one – I shall definitely take that into consideration when we’re looking at modifying our house! Thank-you!



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