Frequently Asked Questions

  

Sustainable “Green” Building

  

Question:     You say Earth Building is the Ultimate "Green" building material.  How do you justify that?

  

Answer:       If the entire life cycle analysis of buildings is studied that is the energy used to construct,

                   maintain and demolish a building and all the energy used operating the building then nothing

                   comes close to earth in terms of minimal energy consumption. Recent research shows earth

                   buildings in Australia using half the power, or operational energy of their neighbours

                   (Soebarto). 

                   The energy consumed in sourcing materials and in construction is the embodied energy.  The

                   embodied energy figures for raw earth are a small fraction of other materials. (see figures below).

  

                   Building Material                       Energy consumption (kWh/m3)

                   Cement (OPC)                                              2,640

                   Fired Brick (solid)                                          1,140

                   Chipboard                                                     1,100

                   Lime                                                                900

                   Plasterboard                                                     900

                   Concrete Block                                             600 - 800 

                   Fired Brick (perforated)                                      590

                   Calcium silicate brick                                         350

                   Natural sand/aggregate                                       45

                   Earth                                                               5 - 10

                   Straw                                                                4.5

                   

                   Data from various sources including Intermediate Technology Development Group and

                   the Centre for Alternative Technology.  Taken from Earth Building by Lawrence Keefe.

         

                   Also read our Earth Building page to see how earth building is appropriate, renewable,     

                   sustainable building technology.                    

           

Thermal Performance

  

Question:     People say homes built with earth walls are warm in winter and cool in summer.  Is it true     

                   earth homes are very comfortable?

  

Answer:       It is certainly my experience and that of people who also live in earth buildings. In fact all homes

                   built with heavyweight or mass walls have stable internal environments because the thermal

                   mass balances daily and even day to day fluctuations in temperature.  So in relation to climate, 

                   time of day and season earth walled homes offer a reasonable temperature inside compared with

                   outside without heating or cooling.  

                   

                   This comfort may not be perfect all year round though depending on your climate it may negate  

                   either the need for heating or cooling for most of the year and offer a predictable, even, gentle

                   radiant coolth or warmth from heavy mass wall surfaces.  This is called free running with

                   natural conditioning.

  

                   Furthermore thermal mass allows the building to balance and store any applied heating or

                   cooling energy and to maintain thermal comfort and efficiency with minimum air changes.

                    

Question:     So if I build an earth building it will be comfortable?

  

 Answer:       Yes, moderatelty to perfectly so.  Thermal Mass should be coupled with Appropriate Climate

                   Responsive Design Principles for the best results with the Autonomous Building

                   being the ultimate goal of the best design.  I would also recommend the use of thermal

                   mass walls internally not just for exterior walls.

  

Question:      Is there any scientific evidence to support the excellent performance of earth buildings?

  

Answer:        We will ignore trial and error and the observations and wisdom of billions of people from     

                    around the world over the past 11,000 years who developed and are living in local vernacular   

                    climate responsive earth buildings.   

                    Yes.  Recent Adelaide University research papers have revealed earth homes are using 

                    half the energy of their neighbours and this is the subject of further research. Research at 

                    Newcastle University with “Think Brick” has proved uninsulated cavity brick buildings (mass 

                    buildings) are out performing light well insulated buildings in energy efficiency.

  

Question:      So, mudbricks and earth walls, generally, must be great insulators? 

  

Answer:        This is what most people believe because earth buildings work so well.  The truth is that,

                    whilst earth buildings are thermally efficient, most earth walls are average insulators when         

                    tested with the same equipment and testing criteria as bulk and reflective insulation. 

                    It is well understood and hotly debated amognst insulation manufactures thar reflective and bulk

                    insulation have differing values in winter and summer.  What is not reconised in this country is

                    that mass has different values as well. The Effective "R" value of earth is different according to

                    solar orientation, exposure and colour for example (McHenry).  Mass, reflective and bulk    

                    insulation are completely different in the way they behave. Only mass has thermal inertia and

                    capacitance.

                    

                    Mudbrick walls 250 mm thick and Rammed earth walls 300mm thick have roughly the 

                    same “R” value as an uninsulated cavity double brick wall roughly R 0.5 (in Australia).         

                    However, earth walls and other mass walls have great “Y” values, admittance.  Admittance  

                    is about energy uptake and release over time.  Admittance is responsible for the thermal

                    flywheel affect that works to balance and maintain comfort in mass buildings.

  

Building on this information so please return to read about Earth Building, Techniques, Energy Efficiency, Testing, Compliance, Appropriate Climate Resonsive Design, Durability of Earth Walls, Cost, Fire Ratings, Density and "R" values and much more.

  

  

 

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