public class Result
    {
        private int id;

        public virtual int Id
        {
            get { return id; }
            set { id = value; }
        }

        /// <summary>
        /// A mapping of runners -> timespans of their individual time usage
        /// </summary>
        private IDictionary<Runner, TimeSpan> _individualTimeSpent;

        public virtual IDictionary<Runner, TimeSpan> IndividualTimeSpent
        {
            get { return _individualTimeSpent; }
            set { _individualTimeSpent = value; }
        }
    }

<class name="Result" table="Result">
   
    <!-- Id -->
    <id name="Id">
      <column name="Id" sql-type="int"/>
      <generator class="increment" />
    </id>

    <map name="IndividualTimeSpent">
      <key column="ResultId" />
      <index-many-to-many
        column="KeyId"
        class="Project.Model.Runner, Project" />
      <element column="ValueTimeSpent" type="TimeSpan"/>
    </map>
   
  </class>

ICriteria criteria = GetCriteria();
criteria = criteria.Add(Expression.Eq("IndividualTimeSpent.Runner.Firstname", name));