Editing Coefficient of performance (section)

==Improving the COP==
As the formula shows, the COP of a heat pump system can be improved by reducing the temperature gap <math>(\Delta T = T_\text{hot} - T_\text{cold}) </math> at which the system works. For a heating system this would mean two things:

# Reducing the output temperature to around {{convert|30|C|F}} which requires piped floor, wall or ceiling heating, or oversized water to air heaters. 
# Increasing the input temperature (e.g. by using an oversized ground source or by access to a solar-assisted thermal bank<ref>{{Cite web|url=http://www.icax.co.uk/ThermalBanks.html|title=Thermal Banks store heat between seasons {{!}} Seasonal Heat Storage {{!}} Rechargeable Heat Battery {{!}} Energy Storage {{!}} Thermogeology {{!}} UTES {{!}} Solar recharge of heat batteries|website=www.icax.co.uk|access-date=2019-04-08}}</ref> ). 

Accurately determining [[thermal conductivity]] will allow for much more precise ground loop<ref>{{Cite web|url=http://www.carbonzeroco.com/field-services/soil-thermal-conductivity-testing/|title=Soil Thermal Conductivity Testing|website=Carbon Zero Consulting|language=en-US|access-date=2019-04-08}}</ref> or borehole sizing,<ref>{{Cite web|url=http://www.carbonzeroco.com/ground-source-heat-pumps/ground-source-heating-cooling/|title=GSHC Viability and Design|website=Carbon Zero Consulting|language=en-US|access-date=2019-04-08}}</ref> resulting in higher return temperatures and a more efficient system.  For an air cooler, the COP could be improved by using ground water as an input instead of air, and by reducing the temperature drop on the output side by increasing the air flow. For both systems, also increasing the size of pipes and air canals would help to reduce noise and the energy consumption of pumps (and ventilators) by decreasing the speed of the fluid, which in turn lowers the [[Reynolds number]] and hence the turbulence (and noise) and the head loss (see [[hydraulic head]]). The heat pump itself can be improved by increasing the size of the internal [[Heat exchanger|heat exchangers]], which in turn increases the [[Heat pump#Performance|efficiency]] (and the cost) relative to the power of the compressor, and also by reducing the system's internal temperature gap over the compressor. Obviously, this latter measure makes some heat pumps unsuitable to produce high temperatures, which means that a separate machine is needed for producing, e.g., hot tap water.

The COP of absorption chillers can be improved by adding a second or third stage. Double and triple effect chillers are significantly more efficient than single effect chillers, and can surpass a COP of 1. They require higher pressure and higher temperature steam, but this is still a relatively small 10 pounds of steam per hour per ton of cooling.<ref>Department of Energy Advanced Manufacturing office. Paper DOE/GO-102012-3413. January 2012</ref>