19-0710 v3.X Handprinting for the Water Petal


Although we have registered under version 3.1, we are looking at choosing the Water Petal conditions of version 4.0, as we understand we can pick and choose (this was mentioned at the LF19 unConference).
For version 4.0 of LBC we see we are allowed to handprint for the Water Petal.
Can we handprint by using excess greywater (greywater will be used to flush toilets in [our project]) to flush toilets in neighbouring buildings? The buildings are owned by the client, and are within the university campus. By doing this we will be offsetting treated potable water consumption in those two buildings and therefore the city also.
It is a tight urban site with 5 metres of cross fall and subsoil conditions are poor. There is therefore no area for a dispersal field of the required size.


To clarify, projects registered under 3.1 may opt to upgrade all of the Imperatives within a Petal to 4.0; they cannot "pick and choose" by individual Imperative.

Note that because some Imperatives appear under different Petals in 4.0 than they did in 3.1, depending on the Petal, it may be necessary to pursue additionalImperatives outside the current 4.0 Petal. This is not the case for the Water Petal, but teams should refer to the graphic in this article that explains further.

Under the 4.0 Water Petal, handprinting is allowed for treatment of grey and black water if on-site treatment is not possible. The Institute acknowledges that the project will reuse greywater to flush toilets on the project, but that there may be additional volume which, because of the site geology, cannot be infiltrated onsite. The team can therefore use the handprinting approach to send the excess grey water to a neighboring building for use in toilet flushing, taking into account the following:

- assuming that the neighboring building receiving the grey water is connected to sewer, the project will also need to offset the additional burden on sewer via efficiency measures in other campus buildings. The certifying project needs to result in net zero added inputs to sewer.
- if pursuing the Energy Petal, the certifying project’s energy balance will need to account for any energy used to deliver the grey water offsite and any other energy used to accomplish the handprinting that would not have been required if handprinting were not implemented. Note that energy from construction of any infrastructure for handprinting must also be accounted for when calculating total embodied carbon emissions for I08 Net Positive Carbon.

As an alternative compliance pathway, the team would be permitted to remain under the 3.1 Water Petal and use the scale jumping approach to send grey water to the neighboring site for use to reduce consumption of potable water, including toilet flushing as proposed. Any excess greywater after distribution for beneficial use may be infiltrated on the neighboring site.

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