create table building
(
   id         integer         not null,
   address      varchar(256)   not null,
   primary key (id)
);

create table buildingproperty
(
   buildingid   integer         not null,
   name      varchar(32)      not null,
   value      varchar(256)   not null,
   primary key(buildingid, name)
);

public class Building
{
   private int id;
   private String address;
   private Properties buildingproperties;

   // getters and setters

   public String getProperty(String name)
   {
      return buildingproperties.getProperty(name);
   }

   public String setProperty(String name, String value)
   {
      buildingproperties.setProperty(name, value);
   }
}

// this class make for mapping
public class BuildingProperty
{
   private int buildingid;
   private String name;
   private String value;

   // getters and setters
}

<hibernate-mapping>
   <class name="Building" table="building">
      <id name="id" type="int">
         <generator class="native"/>
      </id>
      <property name="address" type="java.lang.String" not-null="true"/>
      <map name="buildingproperties">
         <key column="id"/>
         <map-key column="name" type="java.lang.String"/>
         <element column="value" type="java.lang.String"/>
<!--
         <one-to-many class="BuildingProperty"/>
-->
      </map>
   </class>
   <class name="BuildingProperty" table="buildingproperty">
      <composite-id>
         <key-property name="buildingid" type="int"/>
         <key-property name="name" type="java.lang.String"/>
      </composite-id>
      <property name="value" type="java.lang.String" not-null="true"/>
   </class>
</hibernate-mapping>

public class Building
{
   private int id;
   private String address;
   private Map<String, String> buildingproperties;

   // getters and setters

   public String getProperty(String name)
   {
      return buildingproperties.get(name);
   }

   public String setProperty(String name, String value)
   {
      buildingproperties.put(name, value);
   }
}