I am fortunate to live in a dry, high desert climate that lends itself to cooling the home at night with ventilation by wind and fan. I have spent a lot of time trying to optimize night time cooling while decreasing heat gain during the day. It is an ongoing effort. I still leave windows partially open during the day for air quality, although only on the side of the house opposite wind direction as a klunky way to have adequate air exchange during the day but no more than needed since the outside air is hot. June has been hotter than usual during the day, but nights reach nadirs of low 60s F. To my annoyment, the wind picks up in late afternoon and pretty much dies at night. The house has reached a pattern of sorts for now, that is plotted below: The in-house temperature rise duing the day interests me the most. Even though the temperature gradient between in-house and outside rises as the day wears on, the temperature increase rate is greatest in the AM hours. I think two factors are at play: First, the house temp as opposed to the in-home air temperature is likely hotter, and my first few hours of the day are an equilibrium asserting itself. The thermostat may measure 71, but the house is actually 2-3 degrees hotter. Median outside temperature is about the same as median in-house air. I really think I should be able to improve the median in-house air temp to at least 3 degrees lower although I'll declare success at 5 degrees. After all, I supplement cooling at night with fans and tinker with the windows! Second, most of the sunshine that enters the house is during the hours from 7 - noon. I have no idea how to convert the heat entering as sunshine into temperature since it depends on the heat capacity of the house, but every bit matters and the areas where I still have too much sunlight are in queue to be blocked. Advice and anecdotal experience welcome!
I've got a three storey home that lends itself quite nicely to the 'old prairie trick' of opening up the house at night, and closing it during the heat of the day. The chimney effect also works well, and the double-hung windows are great for controlling airflow. I find the house stays considerably cooler in the heat of Summer when I'm up early to let in the cool morning air. When the weather's the hottest, all the windows and doors are closed for the afternoon hours, and opened again in the cool of the evening. I find the house stays cooler by keeping the warm air out, although there's quite a temperature difference between floors. Shade also makes a huge difference, both external to the house, in the form of trees, and internal, in the form of curtains and blinds. Any type of thermal mass will absorb heat during the day and release it at night, so letting the sun shine on your tile floor all day will of course only make it hotter. Getting that mass to soak up the heat from the house instead will make the air temperature cooler, and it feels great to walk on cool tile in bare feet.
Hyo Have you succeeded in dropping the houses air median temperature below outside ambient ? An average of (low+high)/2 is a pretty good appoximation. I have tried closing doors and windows during the day but the house gets stuffy and humid quickly. I find I prefer warmer with some airflow and more pleasant air quality. Do you have a trick I am missing ?
Hi SageBrush. I haven't recorded any measurements, nor even taken any temperatures, so the scientific aspect of my efforts is a complete bust. Around here, there are only a couple of months at best where there's any such thing as 'too hot', and even then, it's a relative term. (Some members of the family are more willing than others to adjust their own temperature through clothing choices.) Still, it's amazing what can be achieved simply by opening and closing windows at the right time. It gets stuffy, but we're used to that for about half the year anyway, when it's too cold to leave the windows open, so a few hours on any given day isn't a hardship in comparison. I love the first warm days of Spring when we can finally air the place out, and am always reluctant to turn the heat back on in the Fall. So, maybe the 'trick' is simply putting up with it, though of course the climates of Vancouver and New Mexico are quite different.
Exactly that is done. I used to have an industrial fan that created quite a bit more airflow, but it is awfully loud. I'll probably buy another for july/august, albeit with quite a few reservations.
I've found an electric fan helpful in blowing cool air into a room at floor level, thereby pushing the warmer air out, but on a whole-house basis, the air seems to move through well enough on its own. With the top part of the upper windows lowered, and the basement door open, the breeze is strong enough that we have to block open an internal door or two.
There are quiet fans, they are a little more money. The other option is get central A/C but get a LEED certified solar to offset the energy costs. LEED | U.S. Green Building Council
In HVAC they call it SEER rating. I only know this cause I installed the AC unit on my home a few years ago. The home was plumbed for AC when it was built in 2000. Finally installed the unit. It's cool by the beach so AC is not that necessary except a few times a year. Some units are more expensive up front but more efficient to operate. The catch is some units are very quiet other loud. If you go to Lowes just ask for a quiet fan. That may be the least expensive start I was hoping you were interested in the central AC and install energy efficient windows, insulating and solar project. The LEED web site is informative. I may be worth while to have a consultant review your home and make a professional recommendation. It may e as simple as a shade tree to block direct sun light on the home to something more complex. Again I'm not an expert just read a little hear and there
SEER is an efficiency rating for heat transfer -- COP adjusted for 4 seasons, if you will. Fan efficiency is pretty much dependent on a decent motor, although I keep hoping that blade design aero technology will make it into residential fans LOL.
AC is very efficient now a days. Specifically not sure if you can meet your guidelines. Many years ago before I was married and purchased a house I rented an apartment. I got 2 window AC units. They are very reasonable and not much elec to run them. One small unit in the bedroom and a larger unit in the living room. Cooled the house when I needed it. Use your current system but if you need the extra cooling you got the window units. When you get older you want to protect yourself from heat stroke. Nice to have the units there just flip the on switch. Here is an example Window A/C Unit Install at Lowe's Thoughts?
Your Like me. I waited 5 years or more before I got the AC installed. We had a heat wave over 100 degrees for a week. My wife put the screws to me about being penny wise and pound foolish. Ordered the AC that year. The Elec bill went up less than $10 a month if that. It's there if we need it. Comfort is priceless. What's your comfort worth? You should at least have a cool room for health reasons. I can say it does clean out the pollen. Helps with the allergies.
What is humidity level? If the place is very dry (desert), then 80° F can be very comfortable. A heavy brick, concrete or other type of wall can accumulate a lot of energy and heat from one side of the wall to come to the other side can take up to 12 hours. The walls cool from both sides during the night and heats considerably more from the outside during a day. Heat from the inside (cooking, fresh air ...) is also not that small factor. The night is probably too short to cool the walls completely to the outside temperature, so the moment you close the house the temperature will go up faster than you would think and will reach or go above the wall temp. Buy a cheap IR temperature meter and measure temperature of the walls from the inside, you may find a spot that heats up faster than others, maybe you can improve that spot. What is the structure of the wall? When you write "passive home" in my area means a house with 30 cm of light insulation and verry thin walls, those houses don't do very good in hot climate, but they need little to no energy in the winter freezing temps.
Quite so. If June was my hottest month I'd be very happy, but July and August are some 5 degrees warmer. LOL
Hey Sage. Did you once use forced air cooling? Are there existing ducts? Also, if you don't mind, can you tell us more about your house? I haven't seen anything about a basement. Are there central hallways? Would it be worth it to you to put in transoms above some of the doors? One thing that doesn't come up very often around here is that I work in the industrial building automation industry: think HVAC for skyscrapers, college campuses, and hospitals, to name a few. But the concepts of heat transfer and human comfort apply at almost any scale. Being environmentally-bent and looking to minimize overall carbon footprints, I like to focus on non-mechanical comfort efforts. To this end, I applaud your efforts. Let's make sure we focus on the basic concept that "one does not make cold insomuch as one removes ambient heat." You have to transfer the existing heat to another medium: pump in a cold fluid through a pipe to absorb and pull out heat, let ice melt which absorbs heat and becomes water, or simply supply cold air to achieve an equilibrium. Without mechanical means to re-chill the fluid in the pipe or re-freeze the ice, you cannot lower the temp in your house to below outside temps; you have no means to trap the heat and move to somewhere else (preferably outside where it belongs). The best you can do is to vent the heat at night (which you are doing) and avoid the heat during the day (7:00 - Noon). My advice is to look at homes in the East and in the South-East. The older homes were built prior to mechanical HVAC and incorporate the best strategies in air movement.
