FacetWP – order by display value numerically

<?php

// Add the following to your (child) theme's functions.php

add_filter( 'facetwp_facet_orderby', function( $orderby, $facet ) {
    if ( 'size_women' == $facet['name'] ) {
        $orderby = 'f.facet_display_value+0 ASC';
    }
    return $orderby;
}, 10, 2 );