A thermal engineer needs to design a thermal storage unit for domestic application.

She determines that the total heat required for a full day of operation is $5\mathrm{.}5kWh.$

She identified two novel options: PCM storage unit and thermochemical storage based on zeolites$/$water$.$

The typical ambient temperature, water mains temperature, and operating storage temperature are $18C,9C,$ and $61C.$

The selected PCM is a bio$-$ester characterised by specific heat capacity $($solid$)$ of $2,210$ J$/($kg K$),$ specific heat capacity $($liquid$)$ of $),$ specific melting enthalpy of $240,000\frac{J}{kgK},$ melting temperature of $35C,$ and density of $821k\frac{g}{m^3}.$

The thermochemical storage has been tested and guarantees a volumetric thermal energy storage density of $143kW\frac{h}{m^3}.$

Indicate which technology requires less volume.

Report with $2$ significant figures the decrease $[\%]$ of volume achieved