Because you leave your windows at least partial open all day. The two most important things that come to mind are shading and internal thermal mass. Given you climate you could there might be possibilities of using water or solar chimneys. If you wanted to pm me with images/ location I might be able to give you more specific advice. Also rotating what rooms are used for what functions per season can help dependant upon the house/inhabitants.
Hi Tony, and welcome back Let's see ... My house has central ducting. It *could* be used for AC if I wanted. Years ago in fact it was also (in addition to heating) used for cooling by hooking up an external 'swamp' cooler. When the swamp cooler broke I never fixed it Home construction: Stucco on frame. Two stories. No basement, no attic. Roof is gravel on polyurethane. I don't know what a transom is. I think most of my focus should be on getting the home closer to the lowest night temperature. If the house started out in the high 60sF in the AM and then gained no more than 10F during the day I would have a brilliant solution. As it is, the house starts out at 72F air, rises quickly to 75F (I presume from equilibration with the home) and then peaks at 82F. This is June, which is fine; July and August however are hotter, and in particular the night cooling last year often left the AM air temp at 75F which makes for an uncomfortable end of day. We don't suffer; I would just like to improve the situation with none to minimal extra electric use.
Hi JoeS, and thanks for posting. The specific location is zip 87122. I am skeptical that adding thermal mass will help, since as it is I am unable to cool my home's present thermal mass down to anywhere close to ambient nadir at night. Does that make sense ? Water is interesting. I was actually mulling over possibilities of 'natural' evaporative cooling in the PM when we open up the house to ventilation. I look forward to hearing your ideas. The Chimney is interesting. I have one, but it has never been used. I should probably open it up, now that you mention it. Thanks!
We did a couple of things about 18 months back: replaced all windows with double panes having infrared blocking, and put another foot of insulation in the attic. Really stabilized our interior temps.
Seems you really want to maximise what you get out of what you have. So I would concentrate on plantings and shading. Horizontal exterior shades on south windows and vertical shades on e/w windows. Since you have a two story house are there any two story spots, if so an operable opening at the top could help draw out heat.
Exactly About 1/2 of my roof is "flat." I think I'll try spraying up a ~ 0.5 cm of water around 8pm to cool down the gravel on the roof. I have high hopes this will let the home come closer to my night ambient air nadir temperature. If I remember correctly the polyurethane insulation is about R6.
Here's what I was thinking with the central ductwork: You can use it to circulate air at night when you have all the windows open. Since the ductwork most likely services all rooms, you can efficiently move the air around thus ensuring the cooler outside is equally distributed. In theory, this should help cool the entire mass of the homemaking it harder to warm up in the morning. You really need to put up some shades on the East side. It sounds like you're getting tons of passive heating in the mornings. Transoms are "windows" above doors. Prior to forced air, you could open windows in each room, open all the transoms, and have airflow with all the doors closed.
I stopped using the ductwork for ventilation when I realized the blower uses 1 kW. My entire house uses about 3 kWh a day. I have some early AM light coming into the house coming into our NE and SE windows, but most of the windows are pretty well blocked. My main SE windows have external 95% shading from blinds. My guess, and it is a guess, is that most of AM temperature increase in the houses' air is from equilibration with the thermal mass of the house.
If your graph is accurate, it looks like your house is heating up between 8 and 8:45-9 even though the inside temp is higher than outside. Do you have graphing of the temps before 8am? I would repeat the suggestion from others that you are getting unwanted passive solar heating. If you can lessen that impact it should help quite a bit. What interior thermal mass do you have? If it never gets down to ambient temperature, there may be a way to correct for that?
What color is the roof gravel? Perhaps you can hang some shading mesh, like used for plants, on the roof to shade the gravel. The less heat the gravel picks up during the day, the less that it can radiate into the house.
Use nature to your advantage. Since you are in a dry climate it is much easier in the net. In the middle east they have been using "wind towers" for centuries. After shading the glass, open vents at the top of the house, and near the base. Add a mist of water (tiny little bits) at the lower opening. The evap of water will cool the incoming air, and the top vents (windows) will create a natural draft. Ideally a Coupola or omni directional vent structure on the roof, as high as possible helps. We spend so much energy (and money) air conditioning our buildings, when some simple but well tested design systems work nearly as well with almost zero energy input. If we allow the natural rules of convection and evaporation in our design, we could reduce our cooling loads considerably. The great irony, in much of the Middle east, they are building buildings with fake wind towers as a homage to tradition, but instead of actually using them, they simply use conventional A/C. go figure! Do a google search for Arab Wind towers and you might be impressed. http://www.ijens.org/105403-6868%20ijcee-ijens.pdf Solaripedia | Green Architecture & Building | Projects in Green Architecture & Building Among a couple, Icarus PS. If you d go with A\C, mini splits are far and away the most efficient and comparatively inexpensive. Small window shakers for single rooms are not too bad for small spaces, but portables, like the one pictured above are far and away the least efficient units you can possibly use! (not to mention, they are very much more expensive to buy on a BTU/BTU basis.)
Solar panels on the roof could shade the gravel, and give you enough extra power to run the furnace fan. One other low-tech wild and crazy idea is to build a wind tunnel. No, not one big enough to put your car in, but one that will bring cool air into your house. If you were to dig a trench in your yard, line it with big rocks in such a way to leave large air gaps, and then cover it over, you could have a steady flow of naturally-cooled air. A few screens in the right places should keep out the critters.
I hope that isn't the only roof insulation. Evaporative roof cooling could work, especially if you don't have any roof insulation. I have see people hook up a sprinkler system on their roof, could be an easy thing to test out. Hopeful you are not in a drought area.
Not quite that bad IIRC the polyurethane is sprayed on board, itself layered on I think a 2X6. Further below but above the room's ceiling is I think 6 - 8 inches of fibreglass insulation. In my area tar and gravel are much more common than polyurethane, so my roof has about R6 more than usual.
I designed my house per Passive Solar House of James Kachadorian. Biggest change is 25% of south-facing walls are windows that are shaded in summer and let in sunlight in winter (with no adjustment needed). I open a vent from my HVAC ductwork in summer, and open two windows at night. Close up the house in morning. Never need artificial cooling and my heat bills are tiny.
Thread revival yay. New guy makes a plug for what appears to be a solid text on this subject. Might as well give the standard plug: Or the TL;DR free summary/subset link https://people.wou.edu/~mcgladm/Geography%20470%20Energy/some%20required%20material/passive%20solar%20house/Passive%20Solar%20House.pdf == Having been to Taos NM I can say that anyone there with tiny heating bills is doing something right. It is not the most challenging place for cooling in summer Generally regarded as a ski resort for Texas. Who call it tay-os (rhymes with chaos). But I digress. == New home construction in US (by commercial builders) has never been linked to thermal efficiency AFAIK. Interfering with free marketplace is bad yes? But an open niche may exist for companies offering efficiency and lower long operating costs, in exchange for (not that much higher) construction costs. Rational governments* might offer incentives for that. The existence of Prius Chat (as a consequence of existence of Prius) suggests that this consumer market exists. Rational governments* I am not implying that any such exist but still...
I once saw an option where long pipes are laid underground and connected to the house, they provide cold during the day and heat during the night.
