When sun is pure gold: A home's value increases by 2.4 per cent for every hour of sunlight it gets
An hour of sunlight a day on a property can add 2.4 per cent to its value, according to a study by economics research group Motu.
More intensive development in cities can increase shading on existing properties and so far there have been no rigorous estimates of the cost.
The Motu authors of the report used more than 5000 house sales in Wellington to come up with their conclusions aboput the amount people are prepared to pay for sunlight when choosing a house or apartment.
The authors chose the core metropolitan area of Wellington because it is small, its economy and housing market have been stable, and it has several hills and valleys, resulting in large variability of sunlight within small neighbourhoods.
These neighbourhoods were affected by man-made features even for houses close to each other.
The average house was a 3.3 bedroom 84-year old home valued at $632,000.
Motu used the geographical coordinates of the property sales in Real Estate Institute data, and merged it with information about elevation, viewspan and direct sunlight exposure, using fine-resolution topographical models from the Wellington City Council.
"We can precisely determine the position of the sun in the sky once we know the location and altitude of an observer on earth and the time of year.
"Considering this information plus the topography, man-made features, calculated zenith angles and elevation, we then determined how much sun a given property receives throughout each day of the year, assuming a clear sky."
The average house in the sample received 8.7 hours of sunlight per day, on average, across the year.
But some houses received just 3.7 hours of sunlight across the year, while some received more than 11 hours.
"These results imply that, regardless of the suburbs where purchasers choose to locate, after controlling for neighbourhood characteristics and house attributes, people are still willing to pay a premium of around 2.4 per cent of the total house value.
"If a multi-storey development was going to block three hours of direct sunlight a day on two houses each valued at $1 million, the loss in value to the house owners is in the order of $144,000.
"Instead of regulating building heights or the site envelope for the new development, the developer could be required to reimburse each house owner $72,000."
"Developers could also use of this information in deciding how much to bid for land."
Motu concluded the value may be higher or lower depending on climate, topography, city size and incomes.
Motu could not find any published research that rigorously estimated the value of sunshine but there were related areas of research.
These studies generally found higher prices for apartments on upper storeys with greater access to sunshine.
However, the level in a building and and the outlook also affect other values such as quality of view and traffic noise.
Another variable affecting property values was climate, with some evidence that better climate which often produced higher sunshine hours also tended to be associated with higher values.
There was also the question of the effect of higher energy costs in cooler "urban canyons" - estimated to add 19 per cent to heating costs.
Many other studies also found a link with better health and sunshine, especially in relation to depression and mood disorders.
"If a relationship between sunshine and health exists, we can expect this to be reflected in the price paid for a house," the Motu report said.
The Motu authors included David Fleming, Arthur Grimes, Laurent LeBreton, David Mare and Peter Nunns.