No storm windows--happily (or sadly for lovers of seasons!) we're in Northern California, where the climate is pretty temperate. (To wit: we've been able to just lean a board over the opening where the window once was for the past week...) At this point we've ruled out insulated glass and are down to deciding between laminated glass and just sticking with single-paned. (We learned that insulated glass will look quite different because the muntins need to be shallower to accommodate the thicker glass; this is apparently less of an issue with the laminated glass because it's thinner.) Still not sure we will get enough benefit from the laminated glass to be worth the extra cost, so it may just come down to the final estimates, which I hope to have today--but still welcome any other thoughts! This post was edited by artemis78 on Mon, Mar 17, 14 at 14:34

We had a similar decision to make except that the casements were to open into a screened porch and we were concerned that while on the porch, people might run into them. We have double hung windows with grills on the top half all throughtout our home but I didn't want my sink centered on a middle piece of wood between two casements. Was just something I didn't personally like for our kitchen. We then saw a similar window to what is in my most recent post which has sliders where the side casements usually are and a large picture window in the middle. WE LOVE IT because it gives us unobstructed view, still has the venting options, screens are on the outside and we felt that having the option of the grills on the side windows, helped it to look more traditional like the rest of the windows in our home....our window is one of the best choices we made - we just love it! I copied my link to my pictures below....you'll see it in the 4th pic down over the sink. Here is a link that might be useful: imlebby's kitchen

My 1926 house has a mix that is orginial to the house (love wavy glass). The living room, breakfast nook and dining room all have casement. The kitchen, bathroom and bedrooms have double hung (and the other bathroom has frosted glass slats that open and close). So I don't see casements as modern nor do I see a mix as necessarily a problem. That said if the whole rest of your house has double hung, I would probably go with that. In my house there's a kind of logic to the differences--"public" spaces at the front of the house have casement, "private" spaces at the back have double hung. Just one different seems like it might stand out more in a not so great way.

The main things you should consider before buying a portable air conditioner or a ductless system include: https://www.air-conditioning-heating.org/ Security - No matter how it's installed, a window air conditioner reduces the security of your home. While it's significantly safer to install one in an upstairs window, you are still making it easier for burglars to gain entry to your home. With a ductless system, Mitsubishi Electric contractors only need to drill small holes in outdoor walls. Suction lines, refrigerant lines and power cables are drawn through it to link outdoor and indoor units. You can rest assured that the security of your home won't be compromised in any way. Convenience - When you use a window unit, you sacrifice an entire window. The room receives less natural light, and you no longer have the option of opening the window to let in fresh air. You can avoid this problem by opting for a ductless system instead. This option allows you to stay cool and comfortable without having to give up an entire window. Flexibility - While a window AC unit can effectively cool a single room, it can't do much else. Advanced models sometimes have extra features like multiple fan speeds and digital displays. Some even have remote controls. Many ductless systems have remote controls too, though, and they have additional perks that you won't find with window units. Most notably, mini split systems can be set up for zoned climate control, which means that you can adjust temperatures in specific rooms. These systems are known as multi-split systems. As an added bonus, indoor and outdoor units can be positioned in a variety of ways to achieve optimal comfort, efficiency and aesthetic appeal. Efficiency - In terms of energy efficiency, ductless systems are the hands-down winners. Some window units are ENERGY STAR rated, but they still don't come close to achieving the kinds of SEER ratings you'll find with mini split systems. Comfort - Window units often seem to have no happy medium. They make rooms too hot or too cold. Mitsubishi ductless systems have specialized sensors that detect small changes in temperature and adjust their speeds accordingly. They are able to do this because they have inverter compressors that are capable of operating at various speeds. What's even better is that ductless systems can also provide heat. The most innovative models feature reversible heat pumps that can add warm air from outside just as easily as they can remove warm air from inside. All of this is achieved with a minimal amount of electricity, so energy bills remain reasonable. Noise - Most window AC units are noisy. Some models are better than others, but you're not going to find one that is completely unnoticeable. Ductless systems make noise too, but they operate a lot more quietly. If noise is a big concern for you, you'll be much happier with a ductless system. Price - You may be wondering "How much do mini split systems cost?" and may be dismayed to learn that they are much more expensive than window units. However, they also last for years and use a lot less electricity. They deliver superior comfort for a lot less money over time, so you should be able to recoup the upfront cost without any trouble.