There is a LOT of lip service on tv and in the media today about "home efficiency". How to design a home or building to be more efficient in heat and cooling, lighting, etc. And that is exactly what this is, lip service. They have not said one thing that is any different from what I have in my Architect and home design and energy books I have in my library from the 60's and 70's. They talk about long eaves, thermal mass, and passive cooling. yet it's impossible to buy such a home. Builders flat out refuse to build these homes because they cant get maximum profits. The typical cookie cutter home that everyone owns is a very bad design. No design to siting the home on the lot, nothing to take advantage of sunlight on the south side. I have even seen homes that have the bulk of their windows on the northern exposure. On top of that the massive lack of skylights in homes, poor thermal design, money spent on cabinets, real wool carpet, and marble counters instead of triple pane windows and real high efficiency HVAC.
But you are not stuck with the really poor engineering and design of your smaller home. Smaller homes take to improvements better than the 2900-8600sq foot mcMansion. The typical 1000sq foot bungalow will enjoy major efficiency improvements when insulation is improved. replacing all the windows with efficient ones is far cheaper for a larger gain. adding the new technology skylights on single level smaller homes is easier as fewer are needed, the roof to ceiling distance is less, and the roof pitch is typically lower. Starting with Skylights. The tube type skylight is very energy efficient and will bring a a LOT of light to a dark hallway or room. Smaller homes having less dark areas can make up a lot of light fill with 1 to 3 of these tube skylights. Doubling the insulation in the home would cost less than $1200.00 and save that much easily over a single season. and upgrading the windows, when you have only 10-15 of them instead of 20-30 windows is significantly less with a larger gain. Most smaller homes and older condos are built on a budget. Therefore any improvement in insulation and windows is typically a HUGE improvement.
without spending a HUGE amount of money you cant fix the short or non existent eaves or add in a thermal mass or add more windows to the south wall. but there ARE things you can do to improve your current home. Even apartment dwellers can do things to improve. Put up the clear window plastic is a very large improvement. More expensive is to have plexi-glass cut to fit in the window openings and using rubber seals, but still very effective. If you have south facing windows that are having a problem letting a lot of heat in during the summer, removable mirrorized window tint will make a huge difference in reflecting that light and heat back away from the inside of the home.