Here is a T'ai Chi  'warm up '  that I have adapted into a partner work exercise. It can be done  in pairs and once people get  to know how it works it can be expanded to 3 people or 4 as shown above.
It is a great exercise to develop awareness of the energy moving between and around people as they practice. Even watching the video one can get a sense of the flow of energy.

Exercises like this one that are simple and repetitive are a good way into the feel of T'ai Chi energy.
 There is so much going on in the T'ai Chi form , so many twists and
 turns , so much coordination that the mind is kept very busy and people  are usually unaware of the flow of energy in and around their body.

Energy awareness is also easier to develop in partner work  ( my opinion ) because of it's nature , what I mean is, when there at least 2 people involved there is a way more energy, not only that but once the partners become attuned to the exercise  and  to each other a resonance often occurs which further  amplifies the energy.

The conscious awareness of energy while practicing the form happens once one is very familiar with the postures and can widen ones focus to include more subtle feelings that up to that point were subconscious.
As with the partner work the form  energy is easier to access in a group
 ( once one has some experience and can practice in a relaxed way ) again this is due to the amplification of the energy and resonance within the group.

The energy was always there , the energy begins to move as soon as one begins the first posture.  The teacher can feel this energy in the room , as can others who have learned enough to be open and relaxed.
All a beginner needs is patience and plenty practice of the form and they too will become  aware of this wonderful  energy flow.