Comparing Milk Packaging Options for Monmouthshire Primary Schools

18th June 2020

WRAP Cymru worked with Monmouthshire County Council to review their choice of switching from single-use plastic milk bottles to re-usable glass milk bottles.

Key Facts
Switching from single-use plastic milk bottles to re-usable glass milk bottles eliminated plastic waste and reduced milk waste;
Less milk wasted meant less milk ordered, which resulted in cost-savings of 39% for the local authority;
The switch is also estimated to have resulted in a 25% reduction in greenhouse gas emissions.

Summary

Environmental impacts are increasingly important in procuring school milk services and must be considered alongside the contract cost and other procurement criteria.

WRAP Cymru worked with Monmouthshire County Council to review their choice of switching from single-use plastic milk bottles to re-usable glass milk bottles.  

As part of the review, an alternative option was also investigated – a pergal system, which allows for the bulk storage of milk in a container that fits in a refrigerated dispenser.

A model was built to estimate the carbon and cost impacts associated with each of the three milk containers.  Findings revealed that both glass milk bottles and the pergal system offered reduced carbon emissions and lower overall costs.

Background

WRAP Cymru reviewed the current provision of milk to Monmouthshire primary school pupils, where a local dairy supplies the milk in re-usable glass bottles.  Once delivered to the schools, staff decant the milk into polycarbonate beakers as required, which are then washed and re-used.  Empty glass bottles are returned to the same local dairy, where they are also washed and re-used several times. 

Previously, each pupil received an individual plastic bottle with a straw, which could not be re-used and did not allow for portion control to minimise wasted milk.

An alternative option is a pergal system, which allows for the bulk storage of milk in a container that fits in a refrigerated dispenser.  Milk is delivered in a large carton, made of a cardboard outer layer and plastic inner skin, and is decanted into re-usable beakers.

Evaluation and Findings

A model was built to estimate the carbon emissions and full costs of each milk container and delivery system.

Weights of materials, transportation distances and energy use were modelled for production, transport, washing and end-of-life. UK government greenhouse gas conversion factors were applied to these model variables to estimate the carbon emissions of each system.

Costs were calculated for the milk, delivery, consumables (beakers and straws), beaker-washing, school staff time and waste management.

The carbon footprint of each option was estimated. It was found that both glass milk bottles and the pergal system had lower carbon footprints than plastic milk bottles in terms of production, recycling and disposal.

Milk Miles

It was established that ‘milk miles’ can tip the balance in determining the most sustainable option.  Findings revealed that carbon emissions from transport were relatively low due to the supplier being within 20 miles of the schools. However, if distances in the glass bottle system were to increase from 60 to 135 miles, for example, it would no longer be more carbon efficient than single-use plastic bottles.  Another local authority in Wales – Pembrokeshire County Council - found that a milk contract using re-usable glass bottles produced the highest carbon emissions of all options, as the supplier had to transport the bottles 250 miles to be washed and re-filled.

Waste and Littering

The milk bottle type also has implications for waste and subsequent carbon impact.

Re-usable glass bottles and pergals produce less by-products, and glass bottles compare particularly well against the priorities of the Waste Hierarchy: reduce, re-use and recycle.

In respect of littering, it was found that single-use plastic bottles are most prone to this if milk is consumed outside of the classroom.

Conclusions

The review highlighted the complexities of choosing an option that meets client, cost and environmental requirements.

With so many factors for consideration, there is no one-size-fits-all solution. However, it was found that for Monmouthshire County Council, their decision to switch from plastic to glass bottles for the provision of milk to primary school pupils was both economically and environmentally advantageous. The following benefits were realised:

  • plastic waste was eliminated;
  • less milk was wasted due to portion control;
  • 23% less milk needed to be ordered, thus reducing contract costs by 39%; and
  • greenhouse gas emissions were considerably reduced by an estimated 25%.