The purchasing process is composed of several elements:

1. Deciding what to purchase,
2. Deciding who to purchase from
3. Negotiating an exchange rate, and
4. Exchanging resources for goods or services.

Purchase Specification

Whether buying on very short demand or developing a tight performance specification, the first move to a purchase is to define the product or service required. Several factors are examined including quality, cost, availability, familiarity with the supplier, etc. Ultimately, the decision to buy is based on how well the purchased item or service meets with expectations. The description of expectations is called a purchase specification. The specification can be developed for a ready-made item or for yet-to-be-designed items.
A specification may include the parameters for delivery, such as routine periodic shipments or on an as-needed basis. The purchase often includes shipping and handling.

Identifying a Green Purchase

A product designed around a single attribute such as recycled content, energy efficiency, or bio-based materials may not "make the grade" as a green purchase. To do so, an evaluation based on multiple, diverse attributes such as chemical composition, toxicity, and biodegradability needs to occur. One way to make a green purchase is to utilize tools that identify and label materials as "green". But if you do not have access to such a tool, a simplified method would be to look at product or service characteristics with an eye to issues identified before, i.e., pollution prevention, resource efficiency, and life cycle perspectives as suggested in the following table:

Product/Service Characteristics	Pollution Prevention	Life Cycle	Resource Efficiency
Material composition	Non-toxic, biodegradable, bio-based	Recycled, reusable, renewable resource	Consumes less water or energy, recycled content
Transport	Produced locally, non-petroleum fueled transport	Administrative or logistical costs	Fewer shipments, shipped by rail or boat, larger quantities, backhaul
Manufacturing	Utilizes best practices, continuous improvement	Environmental Management System, improved compliance	Reduced material waste
Packaging	None or reusable	Requires no special handling	Thinner packaging, recycled content
Product Use	Repairable, reusable, upgradeable, safe, non-polluting	Long life, durable, reusable	Low energy demand, easy to use efficiently
End of Life	Re-useable, fewer incidents	Disposal without long term liability	Fuel blend, less disposed

The supplier should be able to help you find sufficient information for making an informed decision, but as always, caveat emptor, or "buyer beware." Organizations do indeed exist that pay close attention to these issues, as evidenced by the development of corporate environmental reporting programs like the CERES Principles. But others can be less rigorous in their efforts, even fraudulent. The Federal Trade Commission has developed guides to aid the supplier in determining how to substantiate their claims, and a fact sheet to help the purchaser determine the validity of the claims.

Making the purchase

Once the item/service being purchased has been identified in the previous step, purchase specification, a purchasing manager must identify from who to purchase. Purchases can be made between individuals, organizations, or collectives of these.

An appropriate rate of exchange is set and negotiated. The rate is executed through a direct purchase or is documented more formally through a negotiated agreement, or contract.

Finally, an exchange of resources occurs. Typically a fee is set and paid with a purchase order, on credit, with currency, or through electronic means. Other payments, such as bartering, are less common, but still a possibility.