The Valuer General Office (VGO) values land in accordance with the provisions of the Valuation of Land Act 1978. The GRV is the yearly income the property would be expected to generate if rented. The rental value for a house is influence by factors like age, construction, size, car shelters and pools. By analysing property rents against these individual attributes and characteristics it is possible to assess a valuation for all properties, whether they are rented or not.