Thursday, 28 February 2013

Future Buildings - Green technology round-up

I've realised February has almost come and gone without any posts so here are some thoughts I've had on green technology & it's limitations.

High air tightness

The benefits of improved air tightness for energy efficiency are clear - less hot air lost and less cold air for the heating system to warm up. Air tightness is also key if you want mechanical ventilation with heat recovery. However with increased air tightness there may need to be changes in the specification of materials or the design of houses.

Most older houses leak like sieves, which can be a life saver if your boiler starts giving off carbon monoxide. However that's not the only situation where air tightness could cause a problem, there are several sources of gases which could be harmful:
  • Heating: gas leaks or carbon monoxide.
  • Construction, including: Fumes from carpet glues & paints, formaldehyde from panel products and plasticisers from PVC (causing hormonal problems in children).
  • Household chemicals: cleaning chemicals, oil paints, home darkrooms etc.
In addition I think there are some new situations which could be created by highly air tight buildings relying on mechanical ventilation. What happens:
  • If there is a need for increased ventilation due to paint/cleaning fumes etc? 
  • If there is a power cut in the middle of the night when you are asleep? 
  • Where the ventilation/power is turned off and the house is empty & sealed could harmful gasses build up, or oxygen to be depleted by biological processes - similar to the hazards encountered in confined underground spaces.
I think these are all solvable problems but it may require changes to building design:
  • More careful specification of materials to avoid ones which give off fumes.
  • Different cleaning chemicals and avoiding hobby chemicals such as oil paints in favour of cleaner alternatives.
  • A re-think of the place of gas in the home, with a preference to install gas devices externally (if at all) rather than internally.
The whole sealed house approach assumes people won't just leave the windows open - usually the preferred method of getting fresh air, even in the winter. Personally I don't like this kind of sealed box & mechanical ventilation approach to buildings but would prefer some kind of half way house which allows some trickle ventilation at windows. The alternative could be using local ventilation heat exchange at the windows, passive or fan assisted.

Off topic - A quick note on Carbon Monoxide:

This is an invisible odourless gas which regularly kills people despite alarms being widely available (for instance a dual smoke & CO alarm for £30). I know someone who had a lucky escape and someone who worked with someone who didn't. Low levels cause you to feel ill, tell tale sign is that you feel better quickly after getting fresh air. High levels can mean you lose conciousness quite quickly. Although regularly servicing your boiler should help, it's worth having the added reassurance of an alarm. 

Electricity demand balancing

Openenergi (previously RLtec) technology balances electricity demand to supply using remote control of devices where energy use can be deferred. Effectively the opposite to matching supply to demand using fossil fuels (gas turbines) as is widespread currently.

This is a great idea and potentially very cost effective as it simply is about controlling devices intelligently and the rewards can be shared with the energy users. It is well suited to developing electricity grids with significant amounts of power delivered by either renewables or nuclear. I can see this getting in to people's homes too once smart meters are rolled out. An example would be making laptops run off batteries for a short while during peak demand - Toshiba already have something in this ilk with their 'peak shifting' eco utility, but this doesn't link to real time grid information so it is of limited use.

I think this is even more of a winner than a previous top pick MCT turbines who are now part of Siemens. I expect in 2020 electricity demand balancing is going to be big in the commercial sector, and in 20 years it will be everywhere.
Horizontal axis turbines

Vertical axis wind turbines

Quiet Revolution used to sell vertical axis wind turbines, which looked nice but lacked cost effectiveness compared to traditional turbines. The key issue was that they could only work well in very windy locations (coast/on hills) but their key selling point (quieter) was usually not such an issue in those locations. In the city locations where the turbines were recommended for their looks and low noise, it turned out they didn't do much and there were issues of ongoing maintenance.

Vertical axis turbine
It appears that the company is losing it's USP and selling traditional, more effective, propeller type turbines made in in the far east. It's probably a good tack, I have a feeling the small wind industry is going to have a hard time staying a mass market product when value for money is in the spotlight and the initial over-enthusiasm & subsidies are gone. Far too many small turbines were erected in places they were never likely to be effective.
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