Introduction

A tenement building containing 34 apartments was built by conventional means with purpose to reduce the requirement of bought energy by half.

Objectives and target audience

The aim of the project was to build a tenement building with half the requirement of bought energy for heating, building electricity and household electricity.  LKF set the target 95 kWh/m2 bought energy for Jöns Ols.

Financial Resources and Partners involved

The Swedish Energy Agency financed the follow-up and the evaluation of the project.  The Swedish Environmental Protection Agency financed part of the measures and calculations of the project through a local investment program.  Although most of the financial backing was brought about by LKF.  The measures installed cost LKF approximately 90 k€ more then an ordinary building.  Jöns Ols cost 16,4 promille/m2 to build, when compared to an ordinary building.

Process

Jöns Ols is constructed as follows:
-    Conventional building technique with concrete foundation.
-    Thermal bridges is eliminated in all connection as leakage of air.
-    An exhaust air ventilation system was installed.
-    The heat to the radiators is supplied by a heat pump and from district heating when required.  Each apartment can control the temperature.
-    Heat and hot water is measured individually for each apartment and is charged separately accordingly.
-    Heat from the wastewater is recycled via a heat exchanger.
-    A solar collector system with district heating as complement is used for producing hot water.
-    The electrical equipment included i.e. fans and pumps are all energy efficient.

Results

2 years after Jöns Ols were completed the bought energy was measured to 84 kWh/m2, which therefore can conclude that the objective was achieved.  LKF achieved an excess of more than half the bought energy need compared to similar buildings at was also at a very low cost.

Critical Success Factors / Challenges

Success factors are:
-    Good energy and profit calculations
-    The energy measurements have a waiting period of one year before the relevant  results can be recorded.  This is due to the construction moisture that is required to
-    That the correct method to calculate the cost of necessary investments was used.  The pay off method is not recommended as it does not take into account the whole life span of the building.  Use LCC method instead.

Conclusions:
-    The heat pump is very profitable.
-    The solar collector system is not profitable due to it’s design, therefore suggestions could be thought about to improve the design.
-    The wastewater heat exchanger may be just profitable.  The use from the exchanger may be energy wise but could be overrated.
-    The system of measuring the temperature of heat and hot water usage individually in each apartment is not profitable.  Only measuring hot water individually would be profitable.