http://www.green-technology.org/green_technology_magazine/index.php

I describe the Green in Software Engineering as : Efficiency in using IT resources such as efficiency in power consumption, efficiency in space allocation(size of software and hardware), efficiency in memory capacity, availability, usability and storage of data and information, efficiency in  using time schedulling (such as parallel task in software development (RUP,rapid, agile, extreme )-- process model) related with improving human capital for software development in our environment. I think the latest development in Green Software Engineering will related with human capability (machine or system that can understand and give solution based on the 'PATTERN' resulted  from human being) and to support environment sustainability for all activities, and the Sustainability in Software engineering  still related with "TRUST" from the users, and the  common issues still in Security, Privacy, Private data, guaranty of free of error?, updates and patching. This issues must be sustained(improve, fixed, strengthen, reduce the error-failure mean time, improve data protection, etc)in sotware engineering way.

http://www.green-software-engineering.de/en/project.html

See the following papers

Towards greening a campus grid: Free cooling during unsociable hours: https://www.researchgate.net/publication/261400027_Towards_greening_a_campus_grid_Free_cooling_during_unsociable_hours?ev=prf_pub

Towards an architecture for integrated Gas District Cooling with Data Center control to reduce CO2 emission:  https://www.researchgate.net/publication/261523695_Towards_an_architecture_for_integrated_Gas_District_Cooling_with_Data_Center_control_to_reduce_CO2_emission?ev=prf_pub

Conference Paper Towards greening a campus grid: Free cooling during unsociable hours

Conference Paper Towards an architecture for integrated Gas District Cooling ...

While power and efficient architectures are important, I would also recommend looking into the impacts of software maintainability as part of "green" engineering. Building long-lasting software that is efficiently maintainable is too often overlooked.

Check out the IEEE Software Special Issue on Green Software, April 2014.

You might also want to have a look at Software Engineering for Sustainability (SE4S) at UC Irvine.

http://se4s.ics.uci.edu

Also, you might want to have a look at the (much broader) proceedings from the just-finished ICT for Sustainability (ICT4S) conference. The proceedings from the previous (2013) conference can also easily be found online.

http://www.atlantis-press.com/php/pub.php?publication=ict4s-14

The traditional concerns of research in computing - speed, memory efficiency, better cache performance,  lower data transmission size, fault tolerance, software maintainability, etc. - all these can actually be linked to "Green Computing" or "Green Software". So how much of a field on its own actually is Green Computing?

Most papers that deal with Green Computing are to do with: data center's power efficiency,  improving battery requirement of mobile applications.  My own research group has some dealing with Green Computing in the context of grid computing in the tropics, with the aim of distributing jobs to a distributed grid while reducing air-conditioning requirement. So, my thinking is that Green Computing can be a field on its own, but within very specific contexts - Big data center, grid computing, and mobile computing.

Just some thoughts...

some possibly useful discussions:

http://www.cs.cmu.edu/news/green-computing

http://www.ece.cmu.edu/news/calendar/2013/10/agarwal.html

http://www.cmu.edu/gdi/Research/pc-disposal.pdf

http://www.cmu.edu/gdi/comprec/

http://wpweb2.tepper.cmu.edu/ceic/seminarsDetails.asp?id=60 

You could check this workshop, that we are organizing: http://www.iwsm-mensura.org/2014/workshop/megsus14

That is a great question. I would seek out research groups. Seems UC Irvine has some interest, eg: https://www.researchgate.net/publication/255949741_What_does_Sustainability_mean_in_and_for_Software_Engineering

Conference Paper What does Sustainability mean in and for Software Engineering?

the research directions are energy efficient software,measure for green sw ,implementing green sw through requirements