1. As with kWh for energy, you can indicate materials quantities by kilograms , and compare for instance buildings. But what about the quality of materials? And how to evaluate energy performance with their materials impacts? The Questions is how to overcome imperfections of current ways of assessment:
A By avoiding use of weighting factors, to combine different resource impacts
B Not to relate to a ( bad) benchmark, but by indicating the (distance to the) ideal situation where both energy and materials impacts are compensated within the time of use
C to evaluate the whole resource chain, not starting from accidently availability of resource stocks, like fossil fuels.
2. Where do the resources come from in any system? If they come from inside the system, eventually you will run out of resources. If you get them from your neighbors, they will run out faster. The only free resource outside of the system is the sun, sending out radiation into the system that can be captured and converted into food, energy and materials. In order to do this, you need land area to produce a certain quantity and quality over a period of time. That’s the basis for the MAXergy approach and the Embodied Land calculation model.*
3. The principle of MAXergy is to relate all the resources to the amount of solar input needed to generate these resources via the land area needed to capture and convert the solar radiation into useful resources. In other words, to maximize exergy in a system and to prevent the loss of exergy (increasing entropy). The resources used from within the system are therefore required to be restored again within the lifetime of their use. To do this, land area needs to be reserved so that the future availability of the resources is guaranteed. The amount of land area involved is referred to as Embodied Land.
4. For a building it adds up to:
The amount of land occupied over a certain period of time needed to install solar panels that generate the required energy (x m2 year)
The amount of land used for growing crops that are used in building materials like wood, hemp, flax, bamboo, etc (y m2-year)
The Embodied Energy to process the materials and the land area to generate this required energy.
The use of minerals and metals are compensated by calculating the energy, in land and time, to reproduce/restore the mineral/metal from a dispersed sink like seawater
Example 2 MAXergy house
The 4th house to be constructed in the District of Tomorrow, will be optimized by MAXergy and Embodied Land calculations. The total embodied land for this building, per m2 floor , is 5,62 ha-year. If we take only the fraction of renewable materials ( 82% of the building) the EL per m2 floor is 0,08 ha-year . The Embodied Land for the embodied energy in the materials, per m2 floor, is 0,000929 ha-year or, 9,29 m2-year . The operational energy is 0,000053 ha-year , or 0,53 m2-year ( half a m2 solar panel per m2 floor) : If the lifetime of the building is 50 year, it could be divided by 50, to be reproduced over 50 years. Except Operational energy: which is permanent needed: it shows that after ~ 18 years operational energy equals embodied energy in land use. **
Example 1 comparing beams. A basic way to use Maxergy is to compare for instance the use of a wooden beam versus a steel beam (this way only materials impact are evaluated, no operational energy). The table shows: primary land use for harvesting material , the land use related to process energy(embodied energy), based on multi crystalline solar PV panels, and the land use for generating energy to restore the iron use. Note that the cycle in both cases is a closed cycle: the depletion of wood is compensated by the primary land use for regrowing, the depletion of steel is compensated by the energy for the return route via seawater. ( It s in fact a valuing factor for depletion of resources , usually ignored) It also shows in fact all materials are renewable, only the route differs: natural or by human ( =natural…) interference
* there is also a little bit of gravity you can use sometimes in hilly areas).
** these calculations are made by version 0.9. Which had not included the impact of PV panel production, both for operational energy as for embodied energy in construction materials, this is added in version 1.0 and increases the outcomes. (to be published soon)
More background in:
Rovers R. 2009, Material-neutral building: Closed Cycle Accounting for building Construction, paper SASBE conference, Delft, The Netherlands 2009
Rovers R. Et all, 2010, 0-material building: space time analyses, Sustainable Building 2010 conference Maastricht
Rovers R. et all, 2011 , Designing for only energy: suboptimisation. PLEA conference 2011 Louvain la neuve, Belgium
Rovers R. , 2012 , Evaluation of 0-materials house design , PLEA conference 2012, Lima, Peru.