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Modern Brickies are ‘Taking the Pee’

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‘Liquid gold’: students make world’s first brick out of human urine.

The bio-brick created by students in Cape Town mixes urine with sand and bacteria, which they say is a world first. Article from The Guardian newspaper.

Urine bricks created by students at the University of Cape Town.

Creating a truly sustainable construction material is now a possibility

Vukheta Mukhari

“Students in South Africa have created the world’s first brick made from human urine.

The bio-brick was produced by students from Cape Town, who collected urine from specially designed male urinals at the university’s engineering building and mixed it with sand and bacteria.”

More from the article … “Bio-bricks are created through a natural process called microbial carbonate precipitation, said Randall, similar to the way seashells are formed. Loose sand, which has been colonised with bacteria that produces urease, is mixed with the urine. Urease breaks down the urea in the urine, producing calcium carbonate, which cements the sand into shape.

While regular bricks are kiln-fired at temperatures of 1,400C and produce large amounts of carbon dioxide, the bio-bricks do not require heat.”

Original article:

Eco-Friendly Household Cleaning tips.

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Hamburg’s Green-Living House.

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I wrote Green-Living because this IS in many ways a ‘living house – run by green-power.

Hamburg Now Has an Algae-Powered Building

by Mark Hay September 23, 2014.
Photo by NordNordWest/Wikimedia Commons

Last spring, Arup, the design and engineering firm that brought the world the Centre Pompidou and the Sydney Opera House, unveiled their latest hypermodern architectural creation in Hamburg. From the outside, the surface of the 15-unit apartment building just looks like a bubbling green lava lamp stretched over an entire building. But those moving bubbles serve a function: they help to feed and order the living algae embedded within the Bio Intelligent Quotient (BIQ) building’s exterior skin. In turn, the 8-foot by 2-foot glass panels of green scuzz—the building’s $6.58 million bioreactor façade—power the entire structure, making it the world’s first algae-powered and theoretically fully self-sufficient building ever.

Conceived in 2009 as part of Hamburg’s International Building Exhibition, Arup’s BIQ building is part of a European movement to design carbon neutral, self-sustaining, and renewably powered structures. (Germany, for example, is pushing to achieve 35 percent national energy reliance on renewables by 2020.) Alongside a series of houses demonstrating solid timber carbon-locking constructions and greywater recycling systems, the BIQ was funded in large part by the German government as a means to incentivize the development of new adaptive,smart construction materials. Of all the technologies on display, though, algae power has perhaps the finest pedigree and greatest potential.

Research on the energy potential of algae, once just considered a slimy pond nuisance, began in earnest during the gas crisis of the 1970s at America’s National Renewable Energy Laboratory. Producing about five times as much biomass per square foot as soil grown plants, and thriving on carbon dioxide, algae have the potential to grow almost limitlessly and produce oily lipids and gases that can be transformed into relatively clean energy. But official research largely ended in the 1990s as scientists concluded that the benefits of feeding, fostering, and harvesting algae were not yet competitive with then-low oil prices. Still, many independent research groups kept the dream of algae power alive over the next couple of decades, slowly improving the efficiency and cost effectiveness of proposed systems. From 2009 onwards, at least a few plans for algae bioreactors have floated around the design community and academic circles, although few very have become reality.

Photo courtesy of IBA Hamburg

The BIQ is the first residential structure to fully realize the dreams of algae power advocates. The building is coated on its two sun-facing sides with glass-plated tanks of suspended algae. Pressurized air is pumped into the system, feeding the organisms carbon dioxide and nutrients while moving them about—creating the lava lamp effect—to keep them from settling on the glass and rotting. Scrubbers clean off any sticking biomass, freeing up more sunlight for the remaining algae to perform photosynthesis. Periodically, algae are culled, mashed into biofuel, and burned in a local generator to produce power. Excess can be sold off for food supplements, methane generation to external power providers, or stored for future use. The result is a building shaded from summer heat by algae foliage, insulated from street noise, and potentially self-generating the power to sustain its own harvesters, heat, and electricity.

Critics of the design and of algae power in general argue that transforming algae into biofuel requires energy, as does manufacturing and pumping in nutrients. They also take issue with the fact that the BIQ is not totally self-sufficient and that algae technology is more expensive than solar power. They claim that these points make the technology more of a novelty than a useful solution—or at least that its potential has been over hyped.

Even Arup will concede to most of these points, admitting that the BIQ has only achieved 50 percent energy independence thus far. However they believe that total independence is within reach, especially by integrating solar into the design. The costs—$2,500 per square meter for the bioreactor system alone—are astronomical, but the developers hope that as the technology evolves, prices will decrease, while the savings of fuel reduction will offset the remaining extra costs. They hope that soon high-energy consuming businesses like data centers will help pilot their tech in the search for grid independence, and that algae power can take off in residential homes within a decade.

The Arup team is made up of futurists. The same year that they unveiled the BIQ, they released the “It’s Alive” report, envisioning a 2050 with mega-skyscraper vertical farms, jet-powered maintenance robots, and photovoltaic paint, a classic wish list of quasi sci-fi tech. So it’s probably reasonable to question how realistic their optimism about algae power is. But they’re no longer the lone nuts on the road to mass algae power. Grow Energy of San Diego, founded in 2012, has produced two home algae bioreactors and hopes to be able to manufacture, deliver, and install its first systems—generating 35 percent of the average home’s energy with minimal maintenance—for $12,000 per system starting next year.

Meanwhile, in late 2013, scientists developed a very simple technique—basically a specialized pressure cooker—to turn algae into cheap, competitive, biodegradable, non-toxic, and relatively clean oil in just an hour, and believe they can mainstream the technology within 25 years. And just this year, the state of Alabama launched the world’s first algae-powered wastewater treatment plant in the town of Daphne, cleaning water, generating fuel, and serving as proof of concept that the technology is improving, gaining widespread support, and proving itself on larger and larger scales.

Although all of this means we’re likely to see a greater number of more efficient buildings like the BIQ in the next few years, we’re still many years off from an algae generator in every home. But given last month’s pledge by the International Union of Architects to end carbon emissions from buildings by 2050, and similar global initiatives in search of carbon-neutral, self-sufficient structures, the emerging tech is likely to find more champions.

It’s hard not to look at the BIQ, in spite of all its flaws, and see a system that fits the order of the day in every way: a carbon locking, self-sustaining, off the grid, neutral power system. If the only hitch is that, in early stages of development, it’s still a bit pricey and buggy, that’s hardly a death knell for an otherwise optimistic and inspiring tech.

Home Thermostat – that learns your lifestyle.

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The reason we will put a pellet stove in our new home and not a traditional stove that burns wood, is simple.  It’s easier to use. We are fed up stoking the fire and cleaning the ashes from the grate – AND ashes from everwhere else in the room.

Most of that comes from the simple automation that is built into the stove.   Plus unlike a standard wood stove, a pellet stove allows one to set the temperature necessary to maintain comfort using a standard thermostat.

Using the stove means we use 1/2 tank LPG in 18 months.

There’s a company called Nest that has built a smart thermostat.  What makes it interesting is that it learns from how you use it.  Over time, it anticipates your needs (like turning down the temperature at 10 pm every night) and does it automatically.

Further, since it is Internet aware and wireless, you can control if from anywhere (i.e. from your smart phone).

Now, although this tech looks pretty simple, I suspect this device and others like it are the start of a big market for home automation. Essentially, smart systems connected to sensors around your home that makes running a home at peak efficiency, easier than ever.

Nest, with it’s ergonomic/simple approach to design, is certainly going to try to become a leader in this market.



Sustainability in Older Buildings.

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Improving the Insulation on Older/Poorly-Built Buildings.

AKA Raising the B.E.R. on (older) buildings.

The B.E.R. Rating. Building Energy Regulations of a building means to improve it’s insulation and ultimately to lower its eco-footprint and cost in terms of fuel-consumption. It’s a frightening thought that buildings bought before the UK building boom of the ‘80’s (Ireland of the late 90’s) now cost more to heat per year than the initial cost of the building itself. Fuel prices have risen at 1.5 times the rate of inflation over the last 30 years.

It is generally accepted (B.E.R. standards, LEED (US), SAEI- Ireland, Department of Energy and Climate Change (DECC); UK) that 35% of heat is lost from a building via poorly insulated walls.

Heat is lost in ALL directions.

Heat is lost in ALL directions.

The overall heat loss from a building can be calculated as

H = Ht + Hv + Hi   where H = overall heat loss (W)

Ht = heat loss due to transmission through walls, windows, doors, floors and more (W)

Hv = heat loss caused by ventilation (W)

Hi = heat loss caused by infiltration (W).

Heat-loss in buildings (or heat0gain in warm lands demands the value of the building every generation or less nowadays. (Protek-usa. Heat-Gain-Loss-Buildings.pdf). this pdf starts with a very good definition of heat loss via radiation, conduction and convection.

N.B. Sand-cement render on the exterior of a building (especially if insulating the interior) will result in the building ‘sweating’ and possibly developing Merulius lacrimans – dry rot – or -Serpula lacrimans – ‘Real-Dry-Rot’). Both will destroy a building and even its neighbours. If a house is to be ‘sealed’ great care must be taken that it remains “breathable”.

There are two (generally) accepted ways of insulating a building (insulating the envelope);

External; “Bubble-wrapping” the exterior – e.g. polystyrene slabs fixed to the exterior walls (using plastic ‘mushroom’ plugs) and plastering with a patent-polybond-skim over a mesh that holds all in place. This technique ‘defaces’ the exteriors and ‘technically’ needs planning permission.

Cross-section of external insulation.

Cross-section of external insulation.

Internal; fitting patent pre-insulated slabbing to interior walls (ceilings too if possible) to retain the heat generated within the building. Fixed as above or with laths between wall and slab this system is usually seen as the best as it retains heat before it hits the exterior wall and is absorbed (before being lost if there’s no external insulation). This system is often eschewed as it reduces the volume of the room (room-size) considerably in small homes/offices. It is seen as the most desirous in larger buildings as the heat is retained and in fact rather like any light-weight structure (boat-caravan) is easily heated very quickly.

In both cases however the incidence of leakage (drafts) and of course doors, window, and especially glazing must be considered. Poor glazing techniques (ie single-glazing or poorly designed/compromised/faulty) can cost 23% heat loss normally but even far more if the rest of the structure is well insulated.

From ; “Internal insulation systems involve using insulated dry-lining boards. These boards comprise of 12.5mm of plasterboard with insulation bonded to the back with a vapour barrier between the two. The insulation ranges in thickness from about 25mm to approximately 60mm though this depends on the make and availability. A lot of these boards would have similar levels of thermal conductivity because the main types of materials that are used, i.e. polyurethane and polyisocyanurate, have very similar thermal properties. However, it has the disadvantage of placing the thermal mass of the wall outside your heating envelope. External insulation is another option, which would have the added advantage of keeping the thermal mass of the concrete walls within your envelope. It is very popular method in Europe, and is becoming more common in Ireland. With external insulation, the insulation panels are applied to the walls, then a protective mesh that protects the insulation against impact damage is applied, then a basecoat and usually two coats of render”.

Floors are often disregarded as it’s generally thought that heat rises – which is true. But as temperature rises within a structure the heat will always seek to find a way out; even downwards. Floor insulation must reflect what is planned above. 15% heat loss is the accepted figure but again as the better insulation of the upper areas improves the rate of loss through the floor will increase.

Air Seal

A gap of just 1/8 of an inch under a 36-inch door lets in as much air as having a 2.4 inch wide hole in the wall. Since people often adjust the thermostat and leave heat running longer when they feel a draft, preventing air infiltration can greatly reduce energy usage. See ‘Notes’ below.

Air-pressure-tests and infra-red video cameras

will show leaks and vents as well as ‘cool-spots’ in covered areas that are lacking insulation.

Detailed business information on Air Pressure Testing Companies located in the UK, including photos, contact details and customer reviews.

Heat-Exchange Systems. aka Heat Recovery System.

No discussion on heating/cooling any building can Not but consider ‘heat-exchange-system’ see; Heat-Exchange Systems.




‘Geo-thermal’ means absorbing some of the latent heat from the earth (or running water/large body of water) and enhancing the heat by passing it through a heat-exchanger – the inverse of a milk pasteurising system. It’s usually used for underfloor systems (at about 33ºC) though new radiators are coming on the market to work with low-heat-radiators.

Geothermal-Heating-Systems simple


I opened a website on heating on old home and one thing jumped out at me – I hadn’t mentioned the last time – THE most obvious and the FIRST thing ones does – AUDIT. If it ain’t measured it won’t count (or get done).

It’s the most important thing to do – with any structure. Don’t waste money/time until you know where the leaks are. An ait-test and infra-red camera wre the best way to see where the warm air is leaking and where the insulation is needed. Before and AFTER remedial work; More information on blower door tests>>
See; Improve Your Home’s Energy Efficiency – Start With an Energy Audit!
  • Search for articles on old house websites such as the Old House JournalExit EPA Disclaimer
  • Reference books such as Greening Steam: How to Bring 19th Century Heating Systems in the 21st Century (and save lots of green!) by Dan Holohan
  • Ask a question online at
Get this article – very American but less chance that your lecturer will have seen it, excellent resource;  
It’s really difficult to super-seal an older structure though with stone there’s a better chance than wooden/timber-framed however there are a large number of green features and design principles are simply impossible to incorporate in any building after the fact. 
Scotland – links and news; Scotland.national-retrofit-programme 
Heat requirements for the building; Can I fit underfloor heating in an old house?
‘A major factor with UFH in a renovation project is the heat requirements for the building. A system will have a specific max. output, dependent on floor type, and if insulation is limited – e.g. if you have period single glazing and solid walls – it will be difficult to get comfortable room temperatures in very cold weather. Any company you work with must carry out a full heat-loss calculation room by room. It’s also best to have a temperature controller for every room.
‘The two main floor types in old buildings are screeded and timber-suspended. The screeded floor will give a higher heat output, but you will have more difficulties installing UFH, because you will have to dig out the original floors – or lose a lot of headroom putting down a new floor on the original. A timber-suspended floor will accept UFH onto your original joists and give a floor lift of about 1.5cm and so, in many ways, offers an easier option.’ However the insulation must be ‘top-notch- foil-backed etc to ensure heat doesn’t take the easy option of ‘heading South’ – literally. Heat will ALWAYS go to the cold(er) areas.
UK ‘Green Deal’ offers ideas, grants and actual help; Once again they start by demanding one gets an AUDIT first. If it ain’t measures it can’t be counted!! However there are pitfalls to be negotiated; See Gardian article;
Whilst double glazing and carpets are a good start, draught proofing and insulation of suspended floors will be a benefit and for solid floors, the addition of thick underlay and/or insulation. Internal or external solid wall insulation are required to make flats really low energy and will make them really cosy and eliminate many of the condensation and mould issues associated with cold walls, but this should be considered as part of a comprehensive low energy strategy, that in-cavity wall insulation can lead to damp issues in rare cases. For example, the insulation could offer a path for wind driven rain if the external wall is highly porous, poorly pointed or cracked, or the building is extremely exposed. This risk may be reduced if bead insulation is used instead of fibre, but there isn’t much research on this. Breathability is essential !!
In buildings where part of the wall is solid, for example in ring beam construction, the warmer insulated walls may accentuate condensation at the corner of the wall with the floors and ceilings. Finally, the insulation may reveal building faults such as blocked weep holes or missing cavity trays.cludes heating, ventilation, lighting, appliances and renewable systems.The most cost effective way of minimising draughts from a disused chimney is to use a chimney ballon. 1010global./energy-saving-old-homes;
Doing a bit is better than doing nothing – wearing a hat and no gloves is much better than no hat & gloves.
Schools, UK;  Here, Robert De Jong, LessEn programme manager at the ULI, explains the findings, outlines how Dorset topped the table through its sustainable property team and provides schools with tips on how to become more energy efficient.
Climate debate
A basic misunderstanding skews the entire climate debate. Experts on both sides claim that protecting Earth’s climate will force a trade-off between the environment and the economy. According to these experts, burning less fossil fuel to slow or prevent global warming will increase the cost of meeting society’s needs for energy services, which include everything from speedy transportation to hot showers. Environmentalists say the cost would be modestly higher but worth it; skeptics, including top U.S. government officials, warn that the extra expense would be prohibitive. Yet both sides are wrong. If properly done, climate protection would actually reduce costs, not raise them. Using energy more efficiently offers an economic bonanza–not because of the benefits of stopping global warming but because saving fossil fuel is a lot cheaper than buying it.

Passive-Solar Heating. (aka the No-Brainer).

What is a Passive House? It is a building in which a comfortable interior climate can be maintained without active heating and cooling systems. The house heats and cools itself, hence “passive”. By good design and an average 10% ‘extra-spend’ in design and building will eventually save many 10’s of thousands of Euro or Pounds in fossil-fuel heating-bills (and airconditioning). See;

However as we are discussing older buildings we must assume that other than physically turning a building on its axis to avail of ‘solar-gain’ and to build (sympathetically) around it possibly with a forest to cut-down on chill-factor to NW, N, NE. We must concentrate on apertures, walls, roof and flooring. Further measures – keeping the heating-bills down by reducing the temperature by a degree or two can be found in this pdf;

A book issued hand-in-hand with the Anglican Church offers help; Creed and Creation: A simple guidebook for running a greener church. 2007.

Flooring: When insulating the floor is it possible to add underfloor heating? Underfloor heating uses water heated to 33ºC as opposed to ‘normal’ heating (radiators) which runs at 65ºC.

Notes on insulation and ‘off-grid’ homes;

Australia; A push has been made to help homeowners in providing their own power.

In France A push has been made to tax energy wasters and feed that money towards homeowners insulating and providing their own power.;

A newly constructed apartment complex in Newport News, Va., proves that that future may already be on the way. The Radius Urban Apartment complex windows fabricated with Solarban 70XL glass and SunClean self-cleaning glass by PPG Industries. That’s right, windows that will shrink your energy bill and clean themselves. And they’re both Cradle-to-Cradle certified.

According to the company, Solarban glass is a transparent solar-control, low-emissivity glass that lets light through while also acting as thermal insulation. By transmitting high levels of daylight while blocking the sun’s heat energy, windows made with Solarban 70XL glass can reduce summer cooling costs by as much as 25 percent. PPG also claims that Solarban 70XL glass can cut furnace heat loss through windows in half, which can lower heating bills significantly in the winter months.

And now for the best part: SunClean glass is formulated with a proprietary coating that becomes “photocatalytic” and “hydrophilic” after prolonged exposure to sunlight. Photocatalysis enables the coating to gradually break down organic materials that land on its surface, while hydrophilicity causes water to sheet when it strikes the coating so that decomposed materials are naturally rinsed away when it rains.



Creed ; Creed and Creation: A simple guidebook for running a greener church, Gillian

Straine & Nathan Oxley, Aldgate Press, 2007

Department of Energy and Climate Change (DECC);  Accessed 25/01/2013

Heat-Exchange Systems.

National Archives; Accessed 25/01/2013.


RESATS; Accessed 26/01/2013

Telegraph – radiators  Accessed 27/01/2013.

Links and Resources;

Dublin Heritage-Conservation

Heat loss for engineers;

How to get free cavity wall and loft insulation; It’s not too late to get free insulation installed in your home. And if you’re on a low income or benefits, you could get cash or vouchers as well.

Don’t qualify? You can still save on insulation: If you don’t qualify for free insulation for whatever reason, you can still get discounted installation with all of the major energy companies, and others such as Sainsbury’s Energy.

A detailed guide to insulating your home. ExternalWall Insulation Systems (EWIS) can be used on new or existing buildings;

Sempatap Thermal Solid Wall Insulation Materials & Tools;

Passive House (Passivehaus); For passive construction, prerequisite to this capability is an annual heating requirement that is less than 15 kWh/(m²a) not to be attained at the cost of an increase in use of energy for other purposes (e.g., electricity). Furthermore, the combined primary energy consumption of living area of a European passive house may not exceed 120 kWh/(m²a) for heat, hot water and household electricity. The combined primary energy consumption of living area of a standard house is approximately 220 kWh/(m²a) for heat, hot water and household electricity. External Links for more information: and  More info on ‘passivehaus’; The main design features of passive homes include: –

  • Positioning of homes and buildings to avail of free solar energy. Orientation and selection of the correct site for your home is imperative. Proximity to and height of adjoining buildings can reduce your solar gain.
  • Higher levels of insulation help reduce the cost of heating.
  • Air tightness of your home is crucial in keeping all that free solar energy within the home.
  • Locating the majority of your windows on south facing elevations and reducing the size of any north facing windows.
  • As your home is now extremely air tight, mechanical ventilation will need to be introduced. By ensuring that this ventilation has heat recovery the incoming fresh air shall be preheated by the extracted air. This simple measure helps keep your home warm without having to reheat the fresh air.
  • Correct detailing of junctions between the external fabric and windows and doors to reduce heat loss.
  • Introducing solar panels will help produce approx. 70% of your required hot water once sized correctly and positioned to face south to optimise the solar gain.
  • Other simple measures such as using A rated kitchen appliances and fitting low energy light bulbs will help ensure your new home is both comfortable and warm to live in.


Ireland; Better Energy Homes Scheme; see:-

UK; Solid wall insulation – Energy Saving Trust

Solid Wall Insulation Grants, Home Insulation Grants;

Cavity wall insulation –  Homes – Energy Saving Trust;


Air-pressure Testing;

Reasonable behaviour;

Make sure that there are no unnecessary obstructions in front of radiators, heaters and air ducts. · Bleed and clean your radiators on a regular basis to ensure water circulates properly. Clean off the fluff and dust from the grill and filters of convector radiators and heaters.  Install thermostatic radiator valves (TRVs) to prevent spaces from becoming overheated.

Air Seal

A gap of just 1/8 of an inch under a 36-inch door lets in as much air as having a 2.4 inch wide hole in the wall. Since people often adjust the thermostat and leave heat running longer when they feel a draft, preventing air infiltration can greatly reduce energy usage. Sealing up those cracks will make you feel comfortable and keep more money in your pocket. Remember for every cubic foot of heated or cooled air (that you have paid to condition) that leaves your house, one cubic foot of outside air enters!

Looking for just one thing you can do to improve your home’s energy efficiency? Significantly reduce air infiltration. Gaps or cracks in a building’s exterior envelope of foundation, walls, roof, doors, windows, and especially “holes” in the attic floor can contribute to energy costs by allowing conditioned air to leak outside.

Most Common Sources of Air Infiltration:

  • Bypasses (attic access door, recessed lighting, plumbing stacks, dropped soffits, open frame construction, duct penetrations, electrical penetrations, etc.) in the attic floor regardless of the presence of insulation, which by itself is not an air barrier. If you see dirty insulation, air is getting through.
  • Between foundation and rim joist
  • Crawl spaces
  • Around the attic hatch
  • Between the chimney and drywall
  • Chimney flue
  • Electrical and gas service entrances
  • Cable TV and phone line service entrances
  • Window AC units
  • Mail chutes
  • Electric outlets
  • Outdoor water faucets entrances
  • Where dryer vents pass through walls
  • Under the garage door
  • Around door and window frames
  • Cracks in bricks, siding, stucco and the foundation
  • Mudrooms or breezeways adjacent to garages

How radiators work; Telegraph (UK);

As the water flows through the radiators it gives up its heat to the rooms, thus returning to the boiler at a lower temperature. Designed by the Prussian-born Russian; Franz San Galli

A Low temperature heating system requires a larger surface area to provide enough heat energy. Radiators need to be up to 100% bigger to compensate for the lower temperatures. In other words it contains more mass and area.


London Care of Churches Team

November 2007

The Engineering Toolbox; provides;

1. Heat loss through walls, windows, doors, ceilings, floors, etc.>

The heat loss, or norm-heating load, through walls, windows, doors, ceilings, floors etc. can be calculated as

Ht = A U (ti – to)         (2)

Where; Ht = transmission heat loss (W)

A = area of exposed surface (m2)

U = overall heat transmission coefficient (W/m2K)

ti = inside air temperature (oC)

to= outside air temperature (oC)

Heat loss through roofs should be added 15% extra because of radiation to space. (2) can be modified to:

H = 1.15 A U (ti – to)             (2b)

For walls and floors against earth (2) should be modified with the earth temperature:

H = A U (ti – te)             (2c)

Where; te= earth temperature (oC)

Overall Heat Transmission Coefficient

The overall of heat transmission coefficient – U – can be calculated as

U = 1 / (1 / fi + x1 / k1 + x2 / k2+ x3 / k3 +..+ 1 / fo)             (3)

Where; fi = surface conductance for inside wall (W/m2K)

x = thickness of material (m)

k = thermal conductivity material (W/mK)

fo= surface conductance for outside wall (W/m2K)

The conductance of a building element can be expressed as:

C = k / x         (4)

Where; C = conductance, heat flow through unit area in unit time (W/m2K)

The thermal resistivity of the building element can be expressed as:

R = x / k = 1 / C         (5)

Where; R = thermal resistivity (m2K/W)

Using (4) and (5), (3) may be modified to

1 / U = Ri + R1 + R2 + R3 + .. + Ro             (6)

For walls and floors against earth (6) should be modified to

1 / U = Re + SR             (6b)

2. Heat loss by ventilation

The heat loss due to ventilation without heat recovery can be expressed as:

Hv = cp ρ qv (ti – to)         (7)

Where; Hv = ventilation heat loss (W)

cp = specific heat capacity of air (J/kg K)

ρ = density of air (kg/m3)

qv = air volume flow (m3/s)

ti = inside air temperature (oC)

to = outside air temperature (oC)

The heat loss due to ventilation with heat recovery can be expressed as:

Hv = (1 – β/100) cp ρ qv (ti – to)         (7)

Where; β = heat recovery efficiency (%)

An heat recovery efficiency of approximately 50% is common for a normal cross flow heat exchanger. For a rotating heat exchanger the efficiency may exceed 80%.

Resilient Communities – by John Robb

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This is a series of interesting blogs by John Robb. I can claim no credit other than to acknowledge posting them for educational purposes- only. I find that some of these are brilliant, and some  … less so and I can only gather and collate.

Some have inspired me further and some have left me wondering if there’s hope for the human race – however not all of us are  experienced and we all need an ‘in’ – somewhere to get started. Dear reader I leave that to you. I post this to hope to motivate you and perhaps you too will get the RSS directly and join in Robs – Resilient Community.

——-              =======================        ———-

What I Found Interesting This Week 1/19/2013
By John Robb

What makes a home valuable in the 21st Century?

Increasingly, it’s whether the home or the community it is in produces food, energy, and water in abundance.

A home or community that does that well, is a gem.  A place and a way of life that will be sought after.   So, on that note, here’s some ideas I found this week on how to add this capability to your home and community today.

If you are like me, you love to own a greenhouse (or an green-atrium).   For me it’s both the productivity it provides and the aesthetics it adds to a home.  When I think about a greenhouse, I typically think of something akin to thissuburban life support system.

Suburban<br /><br /><br />

Note how the greenhouse is almost as large as the home itself — given that, I’ll give them a pass on the wasted yard space!

However, a greenhouse that big may not be something you can justify yet.  Over time, that will change as growing organic, healthier, high quality food at home and locally becomes easier and more desirable/necessary to do.  In the meantime, you might want to look at smaller, stand alone structures.

If you want to go fully DIY, using recycled materials, here’s aschool project that used plastic bottles that may motivate you:

Recycled<br /><br /><br />

For those into Buckminster Fuller’s geodesic domes, here’s a simple kit called Starplate (you can purchase it here), that you can use for both a greenhouse and a chicken coop.   It’s basically a set of metal connectors, you buy standard wood (i.e. 2×4), cut it, and assemble it.


Here’s also a Geodesic dome kit and software tool for designing and building light weight domes yourself.  It was funded on Kickstarter in 2011 and it delivered ($99 for the kit).   Note that this kit uses dowels and flexible plastic connectors.  So, if you add a covering, it’s probably best to use it for “shading” plants with cheese cloth during extreme heat.  If you do, watch out for the wind.


Speaking of wind or heat… If you live in a place that features both, you may want to build a submerged greenhouse.  Here’s an example of one from project FLORA.  It uses the ground as a heat sink (a place that stores extra heat when you have too much or a source of heat when you have too little) and as a shelter against the wind.   This design will help the greenhouse maintain even temps and it will minimize damage to the structure.

Desert<br /><br /><br />

If you like the idea of a convertible greenhouse — one that you can open and close with minimal effort — here’s an amazing design from a company in Montana.  Unfortunately, the systems are a little pricey and I haven’t found a good DIY design.

Convertible Greeenhouse

If you are really ambitious.  Here’s a self-contained greenhouse called the “Integrated Food and Energy System” that’s being prototyped right.  It combines solar panels (for energy and shade) and aquaponics to produce lots of food in harsh climates (from urban jungle to desert) with minimal inputs.

food palace

Remember, adding a greenhouse is a good way to improve the productivity of your home.  However, don’t over-invest in a greenhouse if you haven’t established a gardening routine yet.  I also suspect a greenhouse + some help from a localfoodscaper (a local farmer or master gardener that delivers organic and micro-farming expertise to subscribers for a fee) would be an extremely effective combo.

Hope this helps get your head around the possibilities.  Keep adding value to your home and your community.  The future is what you make of it.

Resiliently Yours,


3 different generations of Solar Vacuum Hot Water Systems

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It will probably surprise many people to find out that there are different generations of Solar Vacuum Hot Water Systems and ALL are still being sold today. You may have just bought one but which generation is it ?

This is why you see HUGE differences between performance of solar vacuum systems and why there is so much confusion. We have many requests from people who have just bought Solar Vacuum systems and they can’t understand how our customers systems are producing so much more energy than them.


NOTE: This is the first time you have probably heard anything about the different generations of Solar Vacuum Technology anywhere.

FIRST Generation Solar Vacuum Systems, (about 35 years old), still being sold on the market, always compared to flat plates due to their low performance.

How to recognise one ?, simple, it has a single wall (not double skinned vacuum) clear glass tube and a strip of absorber inside.

solar heat pipe generation 1

Fig: First Generation Solar Vacuum System – (approx 35 years old)

Whilst they are still available to buy in very well known BRAND NAMES, they are quite old at this stage. How did they come about. Simple, a bright Engineer about 35 years ago looked at flat plates in sunny climates and made an assumption that if he put the strips of a flat plate absorber into glass tubes, he would improve on the output of flat plate collectors in cloudy climates. Here is a picture of a flat plate solar collector with its covers off.

solar absorber

He simply decided to split the absorber and put it in glass tubes. A new version of this has a direct flow pipe instead of a heat-pipe. THIS IS FIRST GENERATION SOLAR VACUUM HOT WATER TECHNOLOGY.


SECOND Generation Solar Vacuum System’s, (about 25 years old), still being sold on the market, noted for their lack of performance in poor weather and over-heating problems in sunshine. THIS IS THE MAJORITY OF SOLAR VACUUM SYSTEMS BEING SOLD ON THE MARKET TODAY AS THE COLLECTORS CAN BE SHIPPED BROKEN UP IN LONG BOXES.

You will always hear about sizing to only do 90% of your hot water in case of overheating (of course this makes it poor performing in winter), the adding of dump radiators, etc. with this technology. Here is a picture of this type of solar heat-pipe. There is a condensing heat-pipe running into a twin walled vacuum tube with a sealing cap to hold in the heat. The tube always carries a selective coating so it looks black on the outside. The heat pipe then plugs into the manifold and heats up the manifold. When the manifold gets heated, it transfers the heat to the water passing through. This process is fairly inefficient.

solar heat pipe

Fig: Second Generation Solar Vacuum System – (approx 25 years old)



THIRD Generation Solar Vacuum Systems, (about 8 years old), still being sold on the market BUT only a few suppliers make this generation of system, it is noted for more stable performance than Heat Pipes and has reduced the overheating issues on really hot days. It is more expensive to produce and unless it is shipped in one piece, it has to have rubber seals and run at low pressure. THIS IS TYPICALLY CALLED  A U-TUBE OR DIRECT FLOW COLLECTOR.

Here is what it looks like:

solar u tube

You can see that the circulating water runs into the glass tube via copper pipes unlike any of the 1st and 2nd generations where the water only runs in the manifold. The tubes are twin walled and have a selective coating and appear black on the outside.

ONE MAJOR DRAWBACK (and it is a biggie): If this type of collector comes as a kit (and not in one piece out of the box) and has to be assembled at the installation site, then it will cost a significant amount of money to change a tube. The system will need to be drained down, tube changed and then refilled, this is in effect a FULL SERVICE every time you want to change a tube. Typically the new tube will come with all the pipework so can be over £120 a tube ON TOP of the full service cost.

If the collector is one piece and can’t be broken down, then this does not apply, the changing of a glass tube takes seconds, like changing a light bulb and is a few quid at most. THIS IS THIRD GENERATION SOLAR VACUUM HOT WATER TECHNOLOGY.


FOURTH Generation Solar Vacuum Sytems, (about 4 years old), this is proprietary technology to Surface Power. It involves a system wide science called TDLF (thermodynamic laminar flow technology) coupled with MPPTt, (Maximum Power Point Tracking – thermal). Several patents cover this technology which has been developed to create high powered solar air conditioning and solar central heating systems.

You can see its performance in the samples of our live systems 24/7.

The key thing to notice is the different power band, (kWhrs produced) that is the difference in temperature between the collectors and the cylinder/pool/heating system, etc. Normal solar systems go from +3C to +7C and switch on and off all day. Surface Power systems do not work like this, they operate a DELTA T of between +10C and +25C bringing much larger amounts of power in any given day; and can stay running ALL DAY. Even at a DELTA T of +15C, it is still cloudy and many times higher than the average of any of the 1st, 2nd or 3rd generation solar vacuum technology’s.

Here is a Surface Power SP501 solar collector, (we only have the one type, size, shape, tube quantity), why have more than 1 type of solar collector ?, you can’t improve on perfection…


Our best advice:

It is our job as manufacturer to provide you with open and accessible information to help you with your research into solar hot water. All systems shown are customer systems. In the year 2011, You should not have to buy a solar system based on theories, probabilities and hocus pocus, it should be based on fact and examples of real outcomes. We don’t TELL you what you “SHOULD” get, we SHOW YOU what you “WILL” get. Any educational questions can be put to our support desk 24/7

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