Hi Hershel, >>To clarify, such 'on-demand' water heaters are available worldwide on both electricity or gas. Yup. I knew that. Heck, I even saw one on an episode of "This Old House". ;-) But the only ones I have seen 'in person' were in specialized applications like the beast of an RV Elfur's brother bought or marine applications on bigger boats than mine. >>Anyhow, these on-demand systems are FAR more energy efficient than a tank. Yup. Knew that too. However, I also know that these fancy boogers are *not* "the norm" for new or old housing here in the US of A. Maybe I was a bit too concise in my guess at answering the question "Why aren't these the norm in the US?" My guess is (still) that the reason these are not more common in the US is because our fuel costs are so much lower than other parts of the world. These fancy water heaters are, over here, about three times the purchase price of the inefficient tank style water heaters. (Roughly $1200 versus roughly $400.) If these fancy boogers save me $4 a month, that's ... uh, 200 months, ... carry the two ... that's over 16 years to reach breakeven! The fuel costs have to be pretty significant in order to make up that price difference through operating costs in a reasonable amount of time. My guess is that's not the case in the US and that's why we don't see too many of these fancy water heater things over here except in 'boutique' applications. >>Regarding "building green", a friend of mine shared this with me: http://galleryrobinson.com/tmp/buildinggreen.php Cool link! Neat stuff! *MY* experience ... (caps to indicate that this is certainly _not_ an area where I have read or researched extensively [I'm not an expert and I don't play one on TV either!]) ... this is just my personal experience and observations. My experience is that in the US, while a hell of a lot of these products are available, very very few are actually used to any appreciable extent. I don't think many of these technologies would be considered "mainstream" over here. Solar window screens? Yup, mainstream in Houston -- but probably non-existent in Minneapolis. Solar roof thingies? Might be mainstream in Sedona -- but have you seen the price of housing in Sedona? Yikes! For 'normal' housing, nope, I don't think they are mainstream anywhere in the US. I don't think there is any city in the US (or California even) where an entry level 'starter' house makes extensive use of any of these 'green' technologies. In the US these are mostly toys for the affluent - not mainstream applications. Those permalight light bulbs were pretty cool ... But I have 4 recessed light cans in my kitchen. For the price of four of these (at $65-$75 a pop) fancy lightbulbs I can afford to operate and replace a hell of a lot of incandescent bulbs. [Dude! I'm having trouble selling my wife on the $4 squiggle bulbs to improve efficiency. A $70 light bulb? <shakes head /> Man, I'm not *even* gonna tell her about that. No sale. >>AS far as phone-rigged door intercoms, those are available today. Cool! Glad you found those - didn't see anyone reply when you asked earlier. (I haven't seen them ... but I haven't been looking for them either. Maybe the crappy whole house intercom/radio thingies that were overinstalled over here in the past have left folks other than me with a bad taste in their mouths and hurt the market for these.) Peace out, RonL.