I have an idea for a gadget that I think every home could benefit from and that could also help provide valuable data to research organisations like the CSIRO.
Right now Sydney is bracing for what is predicted to be the hottest February day on record. Meanwhile we, like every generation before us, live in a house with no air-conditioning. Luckily the Greeny Flat has a number of significant advantages over most of the houses those previous generations grew up in. We have the benefit of understanding Passive Solar Design and how it works to keep a house cool in summer as well as warm in winter. We have an excellent site that is well protected from hot westerly winds and from the late afternoon sun. The Greeny Flat is correctly orientated to allow our roof overhang to shade the north wall and to minimise the amount of wall area exposed to the hot sun from the west. Our windows are also carefully placed to reduce heat gain from the afternoon sun and all our windows have insulating blinds to help keep heat out during the day. The Greeny Flat is clad in a light-weight material that cools down quickly once the sun is off it. It is properly air-sealed and insulated and has sufficient thermal mass to absorb any excess heat during the day and is designed for good cross-ventilation to cool it down at night. And, most importantly, we understand how to operate the Greeny Flat in such a way as to get the best performance from all of the above features.
This is a key point because even the very best Passive Solar house can be too hot in summer and too cold in winter if it is not operated correctly. In the future this will probably be taken care of by automatic devices that do things like open and close windows and blinds at the appropriate time. These things already exist however we are not that advanced. We are still living by the old adage… ‘Passive House, Active Owner’. This means there are certain things we need to do to keep our home as comfortable as possible and reduce our energy use and running costs.
In summer we have to open the house at night to encourage cross ventilation and to cool down the thermal mass and then close all the windows and blinds during the day to keep the heat out and the cool in. The trick is knowing when to open and close the house. To help us with that decision we are constantly referring to two things, one is an online weather forecast (this allows us to know in advance if extreme weather is coming so we can be prepared)
and the other is our own weather monitoring station and in particular the readings for the current indoor and outdoor temperature.
If the weather forecast tells us that it’s going to be a hot day we start watching the temperature readings early in the morning and the MOMENT the outdoor temperature climbs higher than the indoor temperature we close the windows and doors, draw the blinds and turn off any exhaust fans (because when you blow cool air out of a house you also suck hot air in from outside). In the evening we do the opposite, we watch the weather monitor and as soon as it’s cooler outside than inside we open all the doors and windows to start cooling the house back down.
In winter we keep the windows and doors closed all the time and just open the blinds when the sun is shining and close them when it isn’t. But we watch the indoor humidity level closely because this tells us when we need to run our ventilation system in order to reduce humidity and maintain good indoor air quality. In spring and autumn we keep an eye on the temperatures. If the house feels cold and it’s warmer outside, we’ll open it up and vice versa. So you can see that we refer to our weather monitor every day of the year (and many times a day) to help us decide how best to operate the house.
The other screen we constantly refer to is our energy monitor. This tells us when we have excess solar power and helps us decide when to run appliances or do things like plug in our electric car. (Unfortunately the UK company that made the ‘Wattson Meter’ has gone out of business but there are other good options like ‘Efergy‘ and ‘Smappee‘)
So my idea is for a home monitoring system that combines all of the above. In other words it will display the weather forecast plus the current indoor and outdoor temperature/humidity plus the current energy usage and production. This is the vital information that everyone needs in order to be able to operate their home in the most sensible and efficient way possible. In fact I think it should be mandatory for every home to have this information displayed in a prominent location where it can be seen at all times. It might look something like this only attractively designed.
To further assist homeowners with the efficient running of their house it could be programmed to speak to them and tell them things like, ‘The outdoor temperature just dropped below the indoor temperature, this would be a good time to open up the house and let it cool down’, or ‘Your solar system is making a lot of extra energy right now, this would be a great time to plug in the car’. Of course, in the future this gadget might connect directly to automatic windows and blinds, plus all the appliances in the house, plus the car charger, etc and tell them to operate themselves. But for now it could give helpful advice. It could also be programmed to learn about the particular home and the habits of the residents in order to offer the most useful advice. And now and then it might offer some random piece of wisdom like, ‘Did you know that hanging clothes on the line rather than putting them in the dryer could save you $127 a year?‘. I’m sure you get the idea.
The final benefit of this gadget is that, since it would need to be connected to the internet in order to display the latest weather forecast, it could also send a constant stream of useful data on your home’s energy use/production and the indoor and outdoor climate conditions to a trusted research organisation such as Australia’s CSIRO. If enough homes had this gadget installed it would provide a wealth of information about the way people use their homes, how comfortable they are and how improvements to the home can affect occupant comfort and running costs.
I plan to pitch this idea to the CSIRO as well as to companies that already produce energy monitoring equipment. If anyone reading this has any thoughts about who I should contact or ways I could improve the idea, I’d love to hear from you. Meanwhile, at the very least, get yourself a cheap indoor/outdoor temperature and humidity monitor (I think Bunnings sells them for about twenty bucks) and an energy monitor. I think you’ll find them very useful and helpful.
(p.s. Please note that our strategy of closing the house completely during summer days and opening it up at night works well because our house, and in particular our roof, is very well insulated. In a home with poor ceiling insulation or an unventilated attic it is quite possible that closing the house during the day might cause it to get unbearably hot by late afternoon. Also, different climates require different strategies… what works for us here in the Southern Highlands of NSW might not work at all for someone living in Brisbane for example. You have to figure out how to operate your own house in the best way to suit your climate, your site and your lifestyle. I just hope it involves more than just turning on the air-conditioner.)