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--- efficiency_now:sufficiency [2022/03/31 14:16] – yaling.hsiao@passiv.de
+++ efficiency_now:sufficiency [2022/08/24 14:05] (current) – [Heating with a fan heater] wfeist
@@ Line 19: / Line 19: @@
 ==== Thermal comfort in the room ====
-Did you know that the internal temperature considered comfortable or "bearable" depends significantly on the clothing occupants are wearing! A sweater acts as an extra layer of thermal insulation for the body. The temperature required for optimal thermal comfort when wearing a sweater is approximately 3 degrees Celcius lower than that with just a long-sleeved shirt. Lowering the average heating temperature by three degrees can save 18 to 30 % heating energy. The percentage of energy saved by decreasing the thermostat is even higher in better-insulated buildings; however, the absolute values are so small that the difference plays a less significant role.
+Did you know that the internal temperature considered comfortable or "bearable" depends significantly on the clothing occupants are wearing? A sweater acts as an extra layer of thermal insulation for the body. The temperature required for optimal thermal comfort when wearing a sweater is approximately 3 degrees Celcius (5.4 Fahrenheit) lower than that with just a long-sleeved shirt. Lowering the average heating temperature by this can save 18 to 30 % heating energy. The percentage of energy saved by decreasing the thermostat is even higher in better-insulated buildings; however, in the case of the latter, the absolute values are so small that the difference plays a subordinate role.
 ==== Temporary reduction ====
@@ Line 25: / Line 25: @@
 If the set temperature is reduced only temporarily, e.g. when leaving the building or at night, then the internal temperature, especially of the building components and furnishings, only decreases gradually from time of reduction onwards. This reduces unnecessary energy use when the building is unoccupied, or the occupants are unlikely to notice the internal temperature change (e.g. are asleep). However, the heat output is initially much higher when switching on the heating after the setback because the building components must first be heated up again. Nevertheless, an energy-saving remains, but this is smaller than is often assumed. Even in already well-insulated buildings, this kind of "night setback" still saves energy, even if it's less than in uninsulated buildings, simply because the temperatures drop less due to lower heat losses through the building envelope. Compared to continuous heating, the savings from consistent night setbacks can amount to around 5% (in a Passive House building) and up to 20% (in an uninsulated existing building); on average, this would be an almost 8% saving across the Central European building stock.
-A note for those living in multi-family buildings: out of regard for neighbours, the room temperature should not be below 15°C in Germany. The indoor air humidity should also be regularly checked and, in case of uncertainty, measured1). If it is higher than 55%, the moisture should be reduced by employing ventilation.
+A note for those living in multi-family buildings: out of regard for neighbours, the room temperature should not be below 15°C in Germany. The indoor air humidity should also be regularly checked and, in case of uncertainty, measured((low-cost electronic hygrometers are readily available today.)). If it is higher than 55%, the moisture should be reduced by employing ventilation.
-); low-cost electronic Thermo hygrometers are readily available today.
 ==== Partial heating ====
@@ Line 47: / Line 46: @@
   * The electric power is converted 1:1 into heat with the direct electrical heating systems. Again, this causes a series of undesirable consequences:
   * Cost! The electricity prices for general household use nowadays are regularly much higher than the heat from commonly used heating systems: Even though oil and gas prices are high, the kilowatt-hour price from traditional heating is always lower than that of electricity. Households that regularly use fan heaters or other similar equipment will notice this in the electricity bill. Besides, the heating consumption in old buildings is much higher than average household electricity use. For this reason, as long as the traditional heating is working, we do not recommend using a fan heater.
-  * **Seriously fails the goal!** If the goal is to 'save gas' or limit CO2 emissions, then the user in most countries with significant heating needs will achieve the opposite 2). Especially in winter, when everyone uses a heating system, the electricity demand is higher, so there is usually no surplus from renewable energy 3). With the current renewable-energy limitations, fossil-fuel-based power generation is needed during this period. In the best conditions, this can achieve maximum efficiency of 55%. Each modern furnace using gas requires less fuel. With the fan heater, thus we consume even more gas and produce more CO2 than conventional heating. This situation might change with renewable energy, especially wind energy, in the future, but this will still need many years to be achieved.
+  * **Seriously fails the goal!** If the goal is to 'save gas' or limit CO2 emissions, then the user in most countries with significant heating needs will achieve the opposite. Especially in winter, when everyone uses a heating system, the electricity demand is higher, so there is usually no surplus from renewable energy. With the current renewable-energy limitations, fossil-fuel-based power generation is needed during this period. In the best conditions, this can achieve maximum efficiency of 55%. Each modern furnace using gas requires less fuel. With the fan heater, thus we consume even more gas and produce more CO2 than conventional heating. This situation might change with renewable energy, especially wind energy, in the future, but this will still need many years to be achieved.
 **The emergency - when the heating system fails**
-The traditional fan heater can reach 2 kilowatts (maximum). In an old building, a (small) single room may need to be heated using such equipment (when the doors 4) remain closed). This only works when all residents in that district don't have the same electricity demand. Otherwise, the electricity consumption in these areas will increase severely. This is the situation we don't want. Having several fan heaters in use simultaneously in the same building will quickly reach the limit of the electricity network's limit (not to mention the family's financial limit). In a supply crisis (e.g. for oil or gas), municipalities and energy companies will inform constituents and customers when and where fan heaters may be used, as well as how and by whom. They'll employ limited periods for energy use in different buildings and districts to do this. If this already unpopular approach doesn't work, it could cause even more significant problems with the electricity network.
-Thus, electric space heating should use a **heat pump system**, which only uses about one-third of the electricity to provide the same level of heat. This will also curb overall CO2 emissions. At least when the electricity isn't generated by coal.
+A traditional fan heater can reach 2 kilowatts (maximum). In an old building, a (small) single room may be heated using such equipment (when the doors remain closed). This only works when all residents in that district don't have the same idea. Otherwise, the electricity consumption in these areas will increase severely. This is the situation we don't want. Having several fan heaters in use simultaneously in the same district will quickly reach the limit of the electricity network's limit (not to mention the family's financial limit). In a supply crisis (e.g. for oil or gas), municipalities and energy companies will inform constituents and customers when and where fan heaters may be used, as well as how and by whom. They'll employ limited periods for energy use in different buildings and districts to do this. If this already unpopular approach doesn't work, this could cause even more significant problems with the electricity network.
+Thus, electric space heating should use a **heat pump system**, which only uses about one-third of the electricity to provide the same level of heat. This will also curb overall CO<sub>2</sub> emissions. At least when the electricity isn't generated using coal.
 ==== Literature ====