Earth Notes: On The Homebuilding and Renovating Show, Surrey (2011)Updated 2020-10-30 12:49 GMT.
By Damon Hart-Davis.
As well as trying to convince visitors of the merits of solar PV on whatever grounds (interest was maybe 5:1 money:eco), I took the opportunity to check out the other 'eco' offerings at the show.
One interesting topic is the 'green roof' which helps mitigate storm surges of rain to the sewers and dampens the urban heat-island effect. Not for us since our roof is already full of solar PV, but as Janet Malt of Io Contracts explained, they are possible on roofs up to about 45° pitch with some effort (ours at ~23° would be no problem) and have a loading of ~100kg/m^2 or about 10x that of our PV. Sedum green roofs are simple and popular, but may still need weeding every couple of months if like us there are tall trees close by!
I also had the opportunity to speak to Mark Houghton of the Daikin altherma AHSP people in the flesh, and though I am still keen on the Eco-cute design (water to 65°C in one step without immersion support, and CO2 as refrigerant with consequently much lower global warming potential from any leaks, etc) I was persuaded to look at them again. For example, Daikin now has a two-stage cascaded system to get to well over 65°C without immersion, with CoPs well over 2.5 even in winter. We've had DHW (tap-water) temperatures of ~50°C for a while, partly to avoid scald risks to our young children, but I remain concerned about rad temperatures mid-winter. I'd also be wanting to fold in solar thermal and possibly a thermal store. I'm going to get them to run a simulation based on the data that I have already gathered and see if a simultaneous kitchen-and-heating upgrade tempts...
A fair number of suppliers were touting triple-glazed (3G) doors and windows, which is pleasing, and I spoke to a couple of them in search of a quote for replacing my remaining ageing patio door, including James Byng of Eurostyle Windows.
I'm also thinking about MHRV (mechanical heat-recovery ventilation) again, with a view to controlling humidity/condensation/pong to compensate for our reduced 'unplanned' ventilation and improving heating efficiency. I have need thinking about, for example, a single-room through-the-wall unit such as the Vent-axia HR-25 (circa £300) in the hope that if fitted to the bathroom could also assist (for example) all of the upstairs at night relying on vapour diffision. I even made preliminary BCO/planning/etc enquiries to which the BC view was:
From a Building Control/Building Regulations perspective an application would not be required for the installation of this appliance provided it was installed by a registered electrician who was able to self certify his work under a competent persons scheme
At the show I ran into Craig Brooke of ADM Systems and chatted about the possibilities, with a whole-house solution being what he thought might fit our situation. The initial parameters he needed to know were likely suitable locations for the bulk of the mechanics (eg loft or garage or whatever), air leakage rates, and where ducts might be routed.
One early chat I had was with David Rix of Premier Microelectronics Europe Ltd about the Eseye ("ess-aye") M2M technology that could GSM-enable even domestic-scale renewables installations, allowing remote monitoring and live data collection, using by a telco-agnostic SIM to minimise backspots for such installs. The hardware cost of such a monitoring system might be £100, with a similar setup and running cost per year; probably easy to justify for larger systems in harder-to-reach locations.