human
Compute the sum of all building units.
gpt
```sparql
PREFIX :     <http://example.org/ontology#>
PREFIX rdf:  <http://www.w3.org/1999/02/22-rdf-syntax-ns#>

SELECT (SUM(?units) AS ?totalUnits)
WHERE {
  ?b rdf:type :Building ;
     :hasNumberOfUnits ?units .
}
```