Improving the efficiency of your home, Series 2, heating, cooling, (hot) water
One of the ways to slow the advance of climate change is to reduce your personal carbon consumption. While we can’t efficiently navigate our way to climate neutrality, we can save ourselves time by slowing the rate of carbon emissions and conservation, as negawatts are often the cheapest available form of clean energy (and the least polluting). Even if you need to replace less energy, it is cheaper to do so (if you cut your energy consumption in half, only half the renewables are needed to make it sustainable).
Our houses can appear monolithic – they need heat and / or cooling, they use water and heated hot water, they use electricity, and they need lighting and plumbing. But the structure plus our actions can change the amount of carbon produced by several orders of magnitude. Two equivalent houses next to each other can have 5 to 20 times the difference in carbon pollution produced in everyday use. A 100+ year old leaky house with inefficient appliances and a high electricity consumption that produces tens of tons of CO2 per year can be next to a Passivhaus or Net Zero house, which has very low or no CO2 emissions at all. And there is a huge continuum between these extremes. Many existing homes that are inefficient can be upgraded to varying degrees to reduce their ecological footprint.
This will be a four-part series:
Series one: Insulation and air sealing
Series two: Heating / cooling and (hot) water
Series three: Plug charges
Series four: Build for Net Zero or better
Standard disclaimers apply, all advice is for informational purposes only, CleanTechnica is not responsible for any damage caused by inaccurate information or the tracking of any information provided; consult professional expertise before creating it each adjustments to your home, all information is subject to change as our knowledge evolves, and the coffee can be hot.
This article series focuses on detached and semi-detached houses, but many of the concepts are applicable to all building types.
Solar hot water: These devices capture heat from the sun and use it to heat your water. These are usually very expensive to purchase and install, have a long lifespan and are very expensive technically very efficient.
Solar hot water has a long history and is only available in tank form. The solar heated water is often heated by the sun and then fed to one of the water heating systems already discussed to heat it completely, or sometimes it means that two or more tanks are involved. This can save 0-100% of heating costs, as if you were using hot water during the day or in the evening, it might not need secondary heating at all, but at night it can cool down enough to need some warming up for the morning showers. The changing economy of solar hot water has led to analyzes that suggest solar panels and a heat pump tank are more profitable due to the crash in the prices of photovoltaic panels over the past decade. The daily amount and temperature of the generated hot water also varies per day and season, with summer producing the highest output and winter the lowest.
If you’re considering solar hot water, run the numbers for both types, as prices vary by region. Find an expert who can compare conventional solar hot water with a solar panel / heat pump boiler.
An exception to the poor economy of conventional solar hot water are pool solar water heaters, which can be more cost effective than natural gas pool heaters if they are a bit more fickle, again depending on the intensity and number of hours of sunlight changing throughout the year , and assuming you are not using your pool during cold winters. Run the numbers.
All hot water tanks experience heat loss from the tank walls over time as the perfect insulator has yet to be invented. However, modern efficiency standards have resulted in more efficient tanks with better insulation. Many countries conduct water heater efficiency tests and publish the results, so refer to these when making a choice between units when replacing your water heater. These typically measure a standardized case usage that takes into account burner efficiency and losses in the tank wall.
Also, most water tanks are made of metal, so it is advisable to replace anode rods regularly for a long service life. This prevents the tank from rusting and eventually leaking. You can check the owner’s manual or contact the manufacturer to determine how often they recommend replacing the anode.
The temperature you choose to heat the water also affects its efficiency. Thanks to the laws of thermodynamics, the greater the temperature difference, the faster it becomes equal. So the lower the temperature you set the tank to (all models must have an adjustable thermostat), the less waste heat you will throw away. That said, you’ll want to use a setting of at least 60 ° C (140 ° F) to avoid Legionella bacteria that can harm people. If you’re looking to upgrade to a larger tank, a higher temperature on your current tank can mimic a larger tank, but using only hot water at the tap is more likely to burn yourself unless you use a temperature control valve installed. . But this solution causes more energy loss. Ideally, you should try to use less hot water using the steps from the last few parts of this series.
If possible, make sure all your hot water pipes are covered with insulating tube envelope, available at most home improvement stores. There are several types, although some niche types may need to be specially ordered. Try to find the cloth with the highest R-value, even if you have to order it. Wrap all exposed hot water pipes (allowing for any caveats of a drain pipe), but if you buried pipes in walls, it is often not realistic to remove drywall or plaster / batten to insulate the hidden hot water pipes. However, if you ever get the opportunity to access those pipes, make sure to retrofit the pipe wrap.
An underrated source of water loss is the water wasted by turning on the tap and waiting for the water to heat up. This often measures 1-10 liters (0.25-2.5 gallons) every time you turn on the tap to get hot water, depending on how far the tap is from the hot water tank as the further away and the thicker the supply line the more water is wasted. You can measure how much water you are losing each time you do this with a measuring cup or small bucket. Every faucet in your home has a different loss volume, so measure them all. You can try to reduce this waste by reducing the number of times you ask for hot water each day and you can also try using the wasted water such as watering plants, soaking cooking pots, filling any humidifiers you do get used, and so on. Drinking this water may not be wise, as your tank contains many metals that are not found in cold water.
If you are using hot water, leave the pipes between the tank and the faucet full of heated water. For example, say you run 2L (0.5G) of water to get hot water – 2L (0.5G) to wash your hands. As a result, there is now 2L (0.5G) of heated water in the pipes between the tap and the hot water tank. This meant that 6L (1.5G) of water was heated for 2L (0.5G) of water use. Extremely inefficient. There is no practical way to avoid this waste, although it will warm your home a bit in colder months. You can wrap the pipes with foam tubing that will keep the water warm for a while and hopefully, if the next hot water puff is coming soon, you won’t have to wait for hot water to waste.
Hot water recirculators are available that keep the water in the pipes warm at all times, but these can be incredible energy wasters as they often reheat the same water over and over again. 24/7 / 365.25. They are best avoided unless you can install a model that only recirculates the water once when you are about to turn on the faucet.
Finally, a very small additional tank at the tap is an option. This eliminates the wait for hot water wastage, but not the remainder from the tank to the tap. These are usually electric only, meaning a relatively high cost and often require additional wiring, not to mention the space taken up by the extra tank.
The best ways to keep these energy losses to a minimum are to reduce the number of times you need hot water, combine uses when possible and, if possible, use shorter runs when replacing a tank. Sometimes there is a better filling location that creates a shorter route to frequently used cranes. It may also be possible to use smaller diameter hot water pipes, although gaining access to inner wall pipes is often prohibitively expensive.
In short, everything mentioned in this series of articles is a starting point. While every effort has been made to ensure the accuracy and completeness of the information provided, this cannot be guaranteed. Therefore, don’t think of it as gospel, but as background knowledge for speaking with professional (s) you should consult to analyze and recommend upgrades for your home.
Resources are available in most countries to help you with this, and there is plenty of low hanging fruit in the pursuit of high efficiency heating, cooling and (hot) water.
Read the whole series:
Part One – Oil and propane heating
Part two – Natural gas and wood heating
Part Three – Geothermal and electricity based heat
Fourth part – Air conditioning and geothermal cooling
Part Five – Considerations for HVAC efficiency
Part six – Water saving – baths, meals, dishes
Part Seven – Water saving – Wash laundry, toilets and hands
Part Eight – Other water applications and types of hot water heating
Part Nine – Solar Hot Water and Additional Hot Water Considerations (this article)
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