Does aircraft noise affect house prices?

Economists have studied this for decades. The usual method compares the sale prices of similar homes that differ in how much aircraft noise they get, and works out how much of the price difference the noise explains. The results agree on the direction, a discount, and disagree a lot on the size.

What the reviews of many studies found

Two reviews that pooled the results of earlier studies give the figures most often quoted.

• Nelson (2004) combined 20 studies of airports in the US and Canada. The discount came out at between 0.5% and 0.6% of a home's value for each extra decibel of noise. In practice, a home in a 75 dB zone sold for about 10% to 12% less than a comparable home in a 55 dB zone. The country and the way each study was set up made some difference to the result; most other factors made little.
• Schipper, Nijkamp and Rietveld (1998) pooled 30 estimates from 19 studies. The estimates really did differ, and the differences could be explained by when each study was done, how wealthy the homes in it were and how the study was built.

"Per decibel" here means per decibel of an average noise level, the kind drawn on official noise maps, such as DNL in the US. It is not the peak level of a single plane. Our guide to Lden, DNL and Lnight explains those averages.

Studies around individual airports

Studies of single airports show how wide the range is:

When flight paths or runways change

The clearest evidence comes from changes, because the same homes can be compared before and after.

• Zurich. Restrictions from neighbouring Germany forced an unexpected change in Zurich's flight rules, moving noise onto new areas. Boes and Nüesch (2011) found that rents fell by about 0.5% for each extra decibel. They also found that studies comparing different places at one moment tend to overstate the discount, and that the effect is unlikely to be the same at every noise level. A follow-up by Almer, Boes and Nüesch found that rents took about two years to settle, with a lasting discount where the noise increased and a premium where it fell.
• Berlin Brandenburg. When the planned flight paths for the new airport were published, asking prices fell in the areas under them: by 9.6% on average within 3 km of a planned path, by 11.8% to 12.8% where planes would be below 1,000 m, and by 8.3% where they would be higher (Mense and Kholodilin, 2014).
• Frankfurt. A new runway was announced in December 2007 and opened in October 2011, bringing more noise to parts of southern Frankfurt. Winke (2017) found very little effect on asking prices for flats after the announcement, and a fall of about 1.7% for each extra decibel once the planes actually arrived.

The pattern is that prices move when the noise becomes certain: when routes are published, or when the planes start flying.

Why the estimates vary so much

Being near an airport has value too. Airports bring jobs and easy travel. Around Atlanta, and around Manchester in an earlier study, homes closer to the airport sold for more once noise was allowed for. The net effect on a house near an airport can therefore be smaller than the noise discount on its own.

Buyers do not always know. Near Raleigh-Durham airport, a rule requiring sellers to disclose airport noise lowered the prices of the noisiest homes by 2.9% (Pope, 2008). The noise had not changed; what buyers knew had. The study concluded that published information about airport noise may not be fully taken into account by all buyers. In England, the seller's property information form asks about disputes and complaints concerning the property or a property nearby, but has no question about aircraft noise; our guide to whether sellers have to disclose aircraft noise covers the rules elsewhere.

Averages are not what people hear. Most studies measure noise with the averages on official maps. The Melbourne study found prices followed flight numbers and distance instead. Our guide to counting loud planes instead of average noise explains the difference.

Markets differ. The reviews found that the country, the period and the wealth of the area all show up in the results. A figure from one airport is not a forecast for another.

What this means if you are buying

We don't value houses, and none of this tells you what a particular house is worth. For that, ask a local agent or surveyor who knows the streets under the flight paths. What the research does suggest:

• A price reflects the noise buyers know about. If most buyers view on quiet days, the loud days may not be in the price.
• Changes move prices. Published plans for a new runway or new routes have been followed by falls under the new paths, so check the airport's consultations and plans before you commit.
• The effect takes time to settle, about two years in the Zurich study.

The practical step is to know the noise at the address before you agree a price. Our main guide on how to check aircraft noise before buying a house covers how.