WITH an apocalyptic sense of humour, Angelinos quip they have four seasons—wildfires, downpours, mudslides and earthquakes. The first three usually occur during autumn and winter; the last whenever the fractured rocks beneath the Los Angeles basin decide it's time to release some megatons of pent-up energy.

Actually, because the region is bounded by a frigid ocean on one side and a baking desert on the other, while the sky above is cloudless for over 300 days a year, the temperature varies more dramatically than is generally appreciated. So much so, indeed, that once every month or two your correspondent has to reprogram his home's heating, ventilating and air-conditioning (HVAC) system to adjust for the change in temperature and humidity.

It is a fiddly process, involving some three dozen keystrokes for each of the controllers in the house. The digital controllers used were considered state of the art when the 45-year-old dwelling was torn apart and rebuilt eight years ago. Temperatures can be set for waking time, leaving time, return time and bed time. The settings can be over-ridden temporarily with a couple of keystrokes, and different cycles can be set for different days of the week. The controllers adjust automatically for daylight-saving time, but need to be reprogrammed whenever the system is flipped from heating mode to air-conditioning.

Really, the controllers are digital only in the sense that they have liquid-crystal displays and send their signals as electrical pulses down wires to a pair of HVAC systems at opposite ends of the house. The temperature in the boiler has to be set manually and is usually left untouched all year round. At least it is a Japanese on-demand heater rather than a storage tank.

Apart from the thermostats in the controllers, there are no other sensors inside or outside the building. As a result, there is no feedback to tell the HVAC or boiler to raise or lower the settings according to ambient conditions—nor, indeed, to tell it whether the building is actually occupied. In other words, your correspondent's home is a typical dumb house, ripe for some form of intelligent control.

In conservation terms, the house has been built to the highest commercial standards for insulation. Even without energy-hogging appliances like washing machines and dishwashers being used only at the most optimal times of the day, annual electricity consumption is still a modest 2.4 kilowatt-hours a square foot—about 25% less than the average American home. Ultra-low energy houses, like the Passivhaus standard developed in Germany, manage with an annual 1.5 kilowatt-hours a square foot or less. So, plenty of savings remain to be had.

To get them, though, means knowing a whole lot more about the pattern of energy use than is disclosed in a utilities bill for the previous month (or two, in your correspondent's case). A study done in Florida a decade ago looked at the energy consumption of ten identical houses fitted with the same electrical appliances and equipment. Despite the similarities, there was a huge variation in consumption—with the most energy-intensive home consuming 2.6 times more than the least. In other words, the occupant's behaviour is a crucial factor governing the use of energy. So, anything that changes the way users behave should reap appreciable savings—for utilities as well as consumers.

The so-called “smart grid” attempts to do this by offering customers cheap rates in exchange for letting the utility turn down their thermostats remotely when demand for electricity on the grid peaks. Forgoing a shirt-sleeve environment for one needing a sweater in the winter or a T-shirt in the summer could save the local power company having to switch on thirsty gas-turbines and other peak-lopping generators.

But survey work done by Parks Associates, a market-research company based in Dallas, Texas, suggests that only 15-20% of consumers are willing to sign up for such “time-of-use” or “demand response” programmes. And 35% of customers say they would not allow the utility to control thermostats in their homes at any price. Intriguingly, though, the survey also shows that over 80% of households would pay up to $100 for cost-saving equipment if it chopped at least 10% off their monthly electricity bills.

That is roughly what a residential energy-monitoring system can do. Such equipment measures the power drawn from the grid using a transformer/transducer device clipped on the electricity meter or breaker box. The instantaneous values are sent to a wall-mounted display via the powerline or a wireless connection. The display gives the number of kilowatts being drawn at that moment plus the projected consumption in kilowatt-hours as well as dollars and cents. Some energy-monitoring systems even display consumption patterns from previous months, along with projected monthly electricity costs, monthly peak demand, and the household's share of the greenhouse gases being emitted.

Studies show that providing real-time feedback to customers on the amount of electricity they are using—along with its projected cost—prompts them to cut consumption by as much as 15%. If they had even better information, they would presumably save even more.

For instance, most energy-monitoring systems on the market today provide just the household's overall consumption, and they do so only for electricity. In many places, gas accounts for up to half the energy used domestically. The few really smart energy-monitoring systems that can break the overall consumption pattern down by the kind of appliances using it are not cheap, but they allow consumers to save even more money—by running things like dishwashers and washing machines during the night when electricity rates are lowest.

Having a lot more information about a home's energy consumption than is revealed in a brief monthly statement is all to the good. But having constantly to make decisions about lifestyle according to rules laid down by a local utility can be tedious, to say the least. That is why your correspondent will be queuing up for a radically different type of home energy-management system when it goes on sale next month.

What is special about the approach adopted by PassivSystems, a small company based in Newbury, England, is that it goes way beyond smart meters and focuses strictly on the consumer's needs rather the utility's. “Everyone wants lower energy costs, but few people have enough time in the day to become their home's energy manager,” says Colin Calder, the firm's founder. “Simply giving people more information about energy consumption is not the solution.”

The heart of Mr Calder's system is an intelligent wireless hub which interrogates sensors attached to the HVAC system, the boiler and the various electrical appliances around the home. It monitors their activity and relays the information to an account that the user can see via a personal computer or smart-phone. On being set up, the system learns the user's preferences for four different situations: when the occupants are home; when they have gone to sleep; when they are out for a short while; and when they are on holiday.

Knowing the various times they like to take a shower, the system preheats just enough water at the appropriate time to meet each person's needs. When people go to bed, the system senses which rooms can have their heating or cooling powered down. At the touch of a pre-programmed button, appliances not being used can be switched off and those on standby given just enough juice to keep their memories alive. Forget to push the button before leaving for work, and you can do so remotely by phone.

Trials suggest an intelligent system like this should be able to reduce energy bills by up to 28%. With the hub, controller and various sensors expected to cost around $450 and the installation much the same, your correspondent expects to recover his costs within three years. In the process, his home could become almost as green as those pricey “passive houses” the Europeans build.