ProductList in layered navigation

ProductList.php

<?php
    //...
    public function setCollection($collection){
            //...

                $collection->joinAttribute('hohlkammern', 'catalog_product/hohlkammern', 'entity_id', null, 'right');
                $collection->joinAttribute('hohlkammern_alt', 'catalog_product/hohlkammern_alt', 'entity_id', null, 'right');
                $collection->joinAttribute('ausreissteg', 'catalog_product/ausreissteg', 'entity_id', null, 'right');
                $whereStatement = "
                    at_hohlkammern.value = {$hohlkammern}
                    or at_hohlkammern_alt.value = {$value}
                    or (at_hohlkammern.value = {$hohlkammernPlusOne} and at_ausreissteg.value = 1)
                    or (at_hohlkammern_alt.value = {$valuePlusOne} and at_ausreissteg.value = 1)
                ";
                $collection->getSelect()->where($whereStatement);
            //...
    }