Why
solar
air
?

Buildings are solar collectors where most of the energy received is lost before the occupants gain any benefit.
This is despite the fact that vertical walls are more efficient in using solar radiation in winter when the sun is low - and the heat is needed.
Furthermore, walls facing east or west receive most of the solar energy of south facing walls.
The imaginative Trombe solar wall concept - double glazing on a south facing masonry (thermally massive) wall - has existed for a century.
However, even with renewed interest in the 1970s due to the global oil crises, sadly, very few have been constructed.
This is because it is a “passive” solar energy system - with no moving parts, e.g. electric fans or pumps.  As the design relies on the natural convection of warmed air it requires very large vents in the building’s wall for air to circulate freely.

New design

Improving the design to make an “active” solar energy system - with electrically driven air - frees up the approach to cover much more widespread opportunities.
An active
solar
air
system can be installed on any masonry wall construction - stone, solid brick, brick cavity, brick-faced timber frame or concrete.  The glazing system can even be installed partially or wholly within conservatories.
In addition, the façade can also now be made with strong, lightweight multiwall polycarbonate, frequently used for conservatory roofs and, increasingly, new buildings.

Benefits

These advances secure three major benefits:
1. New & existing buildings

This innovative design has vitally important applications for new buildings. Furthermore, an active system opens up the massive potential of retrofitting millions of existing houses or larger buildings, capable of reducing gigatonnes of carbon dioxide (CO₂) emissions.
2. Higher storeys
Wall areas available on storeys above ground level are also able to be converted, possibly doubling (or more) a project’s energy input and achieving substantial economies of scale.
3. Other heat uses
As a domestic living room is being heated, or after the desired temperature has been achieved,
solar
air
can also heat other cold rooms using the same primary circuit of recirculating internal air.
The energy efficiency and cost-effectiveness of the
solar
air
system are maximised through an innovative underground heat storage design integrated with the solar wall in this primary circuit.
Additionally, pre-heating domestic hot water can be undertaken at the same time or independently of space heating.
A secondary circuit, heating external air in the summer, is also possible for other applications e.g. Jacuzzis/swimming pools, greenhouses/outbuildings or drying food crops.

New buildings

With the rapidly increasing frequency of heat waves from accelerating global warming, there is a massive and escalating problem of overheating in buildings with large areas of south-facing glazing.
This is driving an exacerbating growth in energy intensive air-conditioning demand, which creates an extremely damaging feedback of greater CO₂ emissions causing even greater climate change.
A major approach being taken to stop this repeating in future construction projects is to specify highly expensive solar control glass (reflecting sunshine) in new building designs.
Rather than preventing renewable energy collection, it would be much more cost-effective and sustainable if new buildings reduced the areas of south facing glazing and maximised the areas of solar walls supplying
solar
air
systems.
Furthermore, highly beneficial underground heat stores would be substantially easier to install before new buildings are erected, with the buildings possibly being placed over them.
Builders and architects of new buildings (small/large or single/multiple) can gain technical guidance on incorporating a
solar
air
system by registering, please email: builders@solarair.me

Existing Buildings

Owners of houses and other existing buildings can order a design guide for installing and operating a
solar
air
system.
The guidance focuses on houses but the techniques described may also be applied to retrofitting larger buildings, for which additional information can be provided.
The design guide will help owners of houses and other existing buildings to maximise the energy efficiency and cost-effectiveness of their
solar
air
system.
Further, site-specific advice on individual projects will be available subsequently on request. This can provide:
  1. Personalised guidance on the site-specific plan most appropriate for your building.
  2. Additional assistance with a draft schedule of works for installation.
  3. Ongoing help over installations with joiners, glaziers, electricians and heating engineers, or doing it yourself.

Houses

Most houses have site-specific problems, like particularly cold rooms, possibly with condensation, usually on the north side of the building (or the south side in the southern hemisphere).
If this is the case and it is examined at the design stage of a
solar
air
system, it may be possible to resolve this - and substantially increase the usable size of your house.
Supplying warm
solar
air
to a colder area of the house can be undertaken either when the living room is being heated or after it has achieved comfort temperature.
Compared to living rooms with south, east or west facing windows, cold north facing rooms will benefit even more from daily
solar
air
and evening use of heat stores.
In hot weather, the
solar
air
system can even be used for cooling the house!

Cheaper

Depending on the installation, a solar air system is likely to cost well under £200 per square metre (m²).
The façade could possibly cost less than £100/m², particularly if you do it yourself, and the fans and other equipment have been designed to be inexpensive.
Adding highly beneficial heat storage will increase the investment slightly but make the overall project much more energy efficient and cost-effective.
A
solar
air
installation will therefore probably be a fraction of the price of a domestic scale heat pump, which often cost as much as £10k.
Solar
air
systems should be much cheaper to run as well because heat pumps need a lot of electricity to operate.
Air source heat pumps, especially, require much more power in winter because their efficiency - coefficient of performance (CoP) - falls substantially in cold air, compared to that of more expensive ground source heat pumps.
At least a quarter and probably over a third of space heating demand using a heat pump will be met by peak tariff electricity. In comparison, the
solar
air
fans should use less than 100W in combination.
A conventional 4kWp photovoltaic (PV) installation, particularly with a lithium battery, will also probably be several times more expensive than a
solar
air
system and much less cost-effective.

Greener

In Europe, North America and other cool, temperate climate countries using space heating, power-hungry heat pumps could increase low carbon electricity demand by terawatts.
However, even in these earlier industrialised nations, responsible for most historical CO₂ emissions, there is still not enough low carbon electrical generating capacity growth to meet the urgent targets for the replacement of fossil fuel power.
Furthermore, the necessary strengthening of electricity transmission networks could delay the much-needed massive increase in renewable electricity supply for a decade.
In contrast, the Intergovernmental Panel on Climate Change (IPCC) has repeatedly stated that greenhouse gas emissions need to almost halve by just 2030 for global heating to stay below the dangerous threshold of 1.5˚C.
Meanwhile, global CO₂ emissions have continued to rise and steadily increasing atmospheric concentrations barely show any reducing effect of the covid pandemic economic recession.
Of all the energy sources available for space heating, particularly unsustainable wood burners/woodchip boilers, power-hungry heat pumps and energy-intensive blue or green hydrogen (producing NOx pollution), solar air is probably the lowest carbon approach.
To achieve net zero carbon though, residual greenhouse gas emissions from the life cycles of all low carbon technologies need to be sequestered with carbon negative processes.
The material inputs to the
solar
air
system can be mitigated by carbon dioxide removal (CDR), through e.g. the Carbon Negative Initiative

How do I convert my house for
solar
air
?

Step 1

Please email survey@solarair.me with photographs of your south-facing wall (two if southeast and southwest) of both the external and internal faces, with the orientation as well as the width and height dimensions (in metres).
A
solar
air
system can also (or instead) be installed on east or west facing walls if these have smaller window areas. These are widely available on gable end walls in largely south facing houses.
If you have east or west facing walls with smaller window areas, please also send photographs of these, with orientation and dimensions.
Please also give details of the wall structure - if it is built of stone, solid brick, brick cavity, brick-faced timber frame, concrete, etc. - and if/where there is any insulation.
Where the solar wall potential is limited, a
solar
air
system may also be made with a separate solar energy collector over a heat store or adjacent to it, possibly using an existing masonry wall on a nearby outbuilding
If you are considering using an existing masonry wall on a nearby outbuilding, instead or in addition, please send photographs of this with the distance, orientation and the width and height dimensions.
It is important too to explain how you heat your living room - continuously with solid fuel (e.g. coal or wood) or intermittently on a timeclock with gas or oil.

Step 2

You will then receive a quick, free assessment confirming if a
solar
air
space heating project is viable for your house.

Step 3

If you then order a design guide, for just £1/m² of building floor area (minimum £100), in addition to installation and operation advice, you will also receive guidance on how to maximise the benefits of your
solar
air
system and wider energy/CO₂ saving.
The design guide also includes architectural drawings for the façade detailing, with templates applicable for at least eighteen framing and glazing options for converting your solar wall.
Additionally, alternative designs of heat stores are incorporated, as well as links for specified materials and technologies essential for maximising energy efficiency and cost-effectiveness.
As an introductory offer, with your
solar
air
design guide a draft schedule of works is also included FREE.

Members' feedback and collaboration

All
solar
air
system owners are requested to send photographs of their completed installation and record their experiences with registered installers, builders and architects on the Members’ webpage.
It would be deeply appreciated if they could also confirm if they would be willing to show the system to others considering a project, or media interested in the programme.
Any additional suggestions would be warmly received, whether recommendations for improving parts of the design or the use of social media, or proposals from potential supporters or collaborators.

Registered installers

Potential installers interested in being included in a register to be sent to building owners considering
solar
air
systems should please email installers@solarair.me

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