TREVI index was launched in January 2005 to meet the demand of a growing number of players on the Belgian residential real estate market wishing to have a wide real estate index calculated on a regular basis and based on clear criteria.

TREVI index is based on the sales price of a sample of 7,500 real estate properties listed during the quarter preceding its publication. TREVI index is therefore a barometer of the evolution of residential real estate prices established quarterly on a representative sample of properties spread throughout Belgium. Real estate is on the move! TREVI index assesses its evolution quarter after quarter!

Our sample is supplied every quarter by collecting real estate ads coming from both our partners present throughout the Belgian territory, as well as properties put up for sale by our colleagues, notaries and private individuals.

* since 1 January 1st, 2006, TREVI index has been published quarterly 

Trevi Index, Sources & Methods

1. Observe the residential real-estate market

It is not easy to build databases that record the transactions prices of Belgian residential real-estate structures. In the plurality of available sources, few are those that simultaneously:

  • Are based on a sufficiently representative sample
  • Offer high-performance information collection systems
  • Provide comprehensive information about the features of the exchanged properties
  • And provide data allowing to understand the recent reality of the markets 


2. Sources available to set up a barometer

In order to identify the available statistical sources allowing to understand the residential real estate market, it is interesting to break down the history of the housing transfer in four phases, consisting of the sale of the property, the signature of the sales agreement, the signature of the notarial deed, and finally the registration of the transfer in the registers of cadastral administration (Chart 1)

Processus de mise en vente d’un bien

Through its original system of collecting information related to the prices and characteristics of properties, TREVI Group masters the first two stages of the sales process.

Studies carried out on the basis of notarial deeds come at the third stage of the transfer process: at the time of signing the notarial deed. Three to four months have already elapsed for a property whose sale was followed by an effective transaction, so that a significant part of the information has lost its freshness.

Almost one year after putting a property up for sale, the sales process is completed with the registration of the transfer in the administration records.

In the plurality of available sources, TREVI index is based on data making possible the analysis of recent trends in the Belgian real estate market. This index is presented in quarter t related to the markets observed during the quarter t-1 on a large sample.


3. Geographic coverage and sample size  

Information collected by TREVI Group is related to 7,500 property offers spread all over Belgium in order to guarantee a good geographical coverage. This large sample aims at limiting the quality effect that could be a source of bias in the development of the index.

The assumption of a certain homogeneity of the properties available on the market over the years and the use of a large volume of data, implicitly limit the bias of the quality factor and outliers.

TREVI index is based on an observation of the prices of each market segment per Belgian province.