Being smart with energy means slowing the meters
Tactical planning for being energy-miserly are in our Plan section; our task here is to share our beliefs and the standards we set for ourselves in this design process.
We'll break this up into the same jumps here that we use in the Plans section, but the emphasis here is less about the nuts and bolts planning, more about the underlying philosophies.
No existing lighting technology outperforms LED lighting for energy efficiency.
We could just switch to LED bulbs in traditional sockets but available bulbs have life expectancies of 10,000-25,000 hours while LED fixtures have life expectancies of 50,000-100,000 hours. Bulbs are, well, bulbs, and have to fit into things designed to fit bulbs; LED emitters can be built into rods, ribbons or thin panels, allowing much more design flexibility. And fixtures allow us to escape the stalactites and stalagmites of traditional lighting (which we regard as visually intrusive) without limiting our choices to less welcoming industrial or commercial lighting.
In terms of energy principles, lighting engenders this one:
No lights, no lumens when no one is there.
In other words, lighting doesn't belong in empty rooms. So a control system has to (for lighting and other purposes) place a high priority on reliable occupancy/vacancy settings.
Also, lighting shouldn't be binary - only on or off - it should be able to adapt its brightness and perhaps other attributes to the needs of the moment. That means recognizing not just the time of day, and not just the level of ambient light from natural sources, but also what activities are being pursued so that lighting levels may be set appropriately for those activities.
In short: don't be wasteful, don't be inappropriate, don't be ugly and do be very long-lived.
Our first principle for reducing energy in creating hot water is to not create it, at least not until we need it; that calls for a tankless hot water heater (preferably gas because of its greater cost efficiency). The second is to not maintain it, which means eliminating both gallons of hot water circulating in the pipes and, again, a tank at the hot water heater.
The third is to do everything possible to reduce the amount of energy needed to preheat the incoming water supply up to the target temperature. One way is to create a buffer tank so the incoming well water can be stored at close to room temperature. One way is to use a heat exchanger to capture heat from the shower drain and add a few more degrees to the incoming water supply to the hot water heater. Another is to use a condensing tankless hot water heater so incoming water is piped past the flue, allowing otherwise simply exhausted excess heat from the heater to also boost the incoming water temperature a bit.
There is also a chain of consequence that impacts the longevity and efficiency of any hot water heater involving scale in the source water. Some sort of washing water (meaning whole-house, not just drinking water) treatment system, in addition to anything else it may do, must put a priority on eliminating scale. Scale-free, a condensing tankless hot water heater has a shot of running 40 years without requiring any major repairs or replacement; otherwise, no way.
The design of this house gives us two options for the bonus room, which has both a lavatory and, outside it, a utility sink. A small electric water heater under the utility sink could efficiently serve both, especially if its power is only on during times when somebody is in that space. Alternately, with hot water feeding through well-insulated spaces, it may arrive hot enough soon enough to make a connection with the main water heater acceptable, while also considering the option of separately insulating the pipes.
Will one HVAC system be enough or will it make more sense to install a second, smaller system for the bonus room? The bonus room space includes several smaller enclosed rooms, meaning duct feeds are necessary there. The main house will also do better with a ducted system.
HVAC technology has advanced considerably in recent years. Where older systems were simply on or off in each mode, highly efficient new systems now run at variable speeds, depending on the load facing them, and with enough intelligence to tend to run at a fraction of full power. There are now also gas-electric hybrid systems.
While the AC part of HVAC, air conditioning, serves well for dehumidification, steam injection humidifiers can help complete the job of providing comfortable and appropriate levels of humidity, allowing some relaxation of temperature-alone HVAC contributions. Clever usage of ceiling fans and fireplaces, when appropriately controlled, also join the more-comfort team.
Smart vent controls can also help balance the temperature distribution across a house, reducing flow to rooms that more readily heat or cool so energy doesn't get wasted on overkill. With occupancy/vacancy sensing integration into their control system, it's possible to relax the settings in vacant rooms even more, and increase the degree of that relaxation as vacancies extend to longer periods.
We must also husband humidity, air freshness (with an eye on not allowing carbon dioxide “doldrum” effects), air pressure and noise.
One more principle plays a major role: don't give heating or cooling away, don't surrender it, don't let it get away. The house itself plays a role through tight insulation, but the same principle should also extend to the air delivery system - the ductwork. sealing joints with tight taping plays a role, but even bigger savings are possible through double-wall insulated ducts.
Like lighting, HVAC energy shouldn't go to places where it doesn't benefit people.
Kitchens are a focal point for energy use.
Natural gas, again, offers both cost and control efficiencies for cooking and baking.
Some cooking, for various reasons, may require electricity, but the balance is in the total usage, not in the momentary usage. An electric griddle feature, for example, may end up (depending on the preferences of the occupants) only being used for a few hours a year.
Gas is not a reasonable alternative for toasters , coffeemakers or microwaves; we should note that modern microwaves offer improved efficiency and a lot more intelligence in their cooking skills (though we have yet to find a toaster we love) and, again, tend to run for only minutes at a time.
Higher efficiency selections in refrigeration and dishwashing and garbage disposals are available, as are quieter models.
Vent hoods can be made a bit more efficient by getting them to read the temperature of a cooktop and turn themselves on and off, meaning no extra running time if switched on earlier than needed or switched off later than necessary.
The energy story in the laundry room lies mainly in the selection of equipment. HE (high efficiency) washers and dryers are engaging advanced features (steam comes to mind) for more dexterous handling of their respective chores.
Load capacities should be appropriate to the needs of the occupants; it makes as little sense to always run bigger, heavier drums as it does to have so small a capacity as to require running extra loads.
Gas for drying offers better energy economy than electricity.
Note another chain of consequence here worth addressing: in a house that adjusts itself to occupied versus vacant locations, there are some efficiencies to be gained by reducing the indoor travel necessary while doing the laundry. A slightly larger laundry room that can include handier facilities for storing baskets and expendables, for hanging or folding finished items and, essentially, for letting more get done there with less running around can provide savings in both fuel and human energy.
While we tend to view a swimming pool as an energy and money sink (no pun intended), pools can be important to the enjoyment of a property, so we need to consider some of the energy elements.
Pumping water to keep it filtered, heating water to keep it comfortable, running automated cleaning equipment and lighting the pool ... this short list seems to cover most of its energy requirements.
In our Plan section you'll see a way to use trapped heat above the roof to warm up the pool water.
LED fixtures, whether surrounding the pool or underwater, offer an answer for energy efficiency in lighting.
If and when we commit to a pool, we'll need to investigate the energy profiles of the newest pumping and cleaning gear; until then, we can only plead ignorance.
We probably feel about insulation much the way we feel about sensors for automation: just once is never enough.
While the SIP walls of the house offer outstanding insulation, we still believe the siding outside should also have an insulation backing.
While the insulated concrete forms that create the crawl space under the house offer remarkably good insulation, we still believe in using spray polyurethane closed-cell foam to insulate between it and the flooring, plus engineered wood in the joists to cut down on thermal bridging, foam on the attic ceiling, heat-shedding on the roof and so on.. No matter how many panes of which glass and gas combo form each window, we still want thermal breaks within the window frames to keep outside temperatures from transiting the frame.
The principle here is simply that insulation stops energy loss and no single measure is complete.
And the more we stop, the more we save.
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