MAYBE a new light, NOT the whole house or even replace the circuit box.

The one with the grass cut neatly and landscaped, and with no couches on the porch :) .

If the walls themselves are not tight (almost a guarantee) look at putting gaskets behind switch/receptacle plates on external walls to stop drafts ... do the same with light fixtures if there is no effective vapour barrier to the attic.  

Traffic is light, and for the most part people that work weekends will be at work and people that are off/don't work will still be in bed/inside. 

As far as returns, are you willing to do any light rehab (carpets, paint) to get a discount to get those returns you're looking for? 

Skylights are an easy addition to my renovations; they provide plenty of natural light (i.e. kitchens, bathrooms).

As well as, landscaping, most exterior repairs (gutters, new fences, paint, etc) are covered.

Fully landscaped the backyard to add a fire pit and comfortable common space.

I'm trying to figure out other financing ideas and hoping someone here can shed some light.  

Replacing lighting and removing some of stuff.