Alternative delivery methods are classified into two methods of construction, they are, (a) Design/build method and (b) Design bid- build method.

The traditional bid-build method consists of the overall owner of the project, then it is further connected to a resident engineer who does the day to day oversight of the construction. This further leads to the designer, the construction manager (this is the adviser during construction) and the general contractor these people can also be called the sub contractors.

In this kind of method, advertisement is done to promote their products, there are open bids for who should or can take ownership of the project. The lowest bidder gets the job.

Advantages of bid- build method include;

1. It is a familiar delivery method.
2. It has a simpler process to manage
3. It is a fully designed scope for both design and construction
4. Both the design team and the contractor are accountable to the owner

Disadvantages of bid-build method

1. Linear process equals longer schedule.
   
2. There is no control over contractor selection.
3. No design or cost input from contractor
4. It can create adversarial relationships

For the design/ build method, a single entity provides for both the design and construction of the project. The owner contracts the architect/engineering firm at the same time as the contractor, as a team. The design is not complete without procurement of design. This usually requires plans to be at 25-30% completion, and is a non-linear process in which design and construction overlap

Advantages of design/build method

1. Single point of accountability for design and construction.
2. Enables fast-track delivery because   construction begins before design is   complete.
3. Project cost defined early in the process.

Disadvantages of design/build method

1. Design-Build firm controls contingency
   
2. Not suited for small projects
3. Requires additional design effort
4. Change management may be expensive.

Green buildings are buildings/ structures that have a lot of resource efficiency. They are environmentally responsible when it comes to how long the structures last. Green buildings can also be called green construction or sustainable buildings. The resource efficiency spans from the construction to the demolition of the buildings. Constructing a green building requires massive cooperation between the design team, the architects, the engineers, and the client at all stages of the construction project. A common objective for the construction of green buildings is that green buildings are mainly designed to reduce the overall impact of the built environment on human health and the natural environment. This is done by doing the following;

• Usage of  energy, water, and other resources very effectively and efficiently.
• Maintaining good health of occupants and improving the productivity of employees.
• Reduction of waste, pollution.

Benefits of Green Buildings

Green buildings impact greatly on human health. They also impact enormously on the economy and environmental well being.

Some of the environmental benefits include:

• It enhances and protects biodiversity and ecosystems.
• It improves air and water quality.
• It reduces waste streams.
• It conserves and restore natural resources.

Some of the economic benefits are:

Some of the social benefits include:

• It enhances occupant comfort and health.
• It heightens aesthetic qualities.
• It minimizes strain on local infrastructure.
• It improves overall quality of life.

The image above is the anatomy of a green building, in more details.