Larger buildings

Knattholmen Campsite - Commercial building

HYSS customer, Norway
Knattholmen Campsite - Commercial building


Knattholmen Campsite is located in Vestfold about 8 km east of Sandefjord by the idyllic Tønsbergfjorden. The camp has been in operation since 1923 and is owned by Vestfold and Telemark YMCA-YWCA. None of the buildings remains from that era, but the oldest cabin standing here are from 1937, tells Chairman Tore Nicolaisen. We have been developing steadily over the last 30 years and the latest building was inaugurated in April this year. We have now 16 buildings with a total of 4500 m² for the entire campsite. We run school camps 20 weeks a year with a total of 2000 students who mostly come from inner parts of Eastern Norway, tells Tore, but we also have participants from Svalbard. We have visitors all year round, but naturally less activities in the period from November to February. We have an average of about 150 visitors a week, he says further, ranging from Christian camps for children, youth and adults, school groups, marching bands, scout troops, confirmation camps and private events.



Such large building lots requires a lot of energy for heating. We were really quite early to make use of geothermal energy for heating, tells Tore. We drilled five energy wells and installed ground source heat pumps back in 2001/2002. We were utilizing this geothermal heat for heating the administration building. Nevertheless in 2015 we had  a total power consumption of 455,000 kWh for the entire resort. This represents a significant operating cost for us. In addition there is also an environmental accounting in this. We have throughout our operation attempted to reduce our emissions in order to conserve the environment and climate, says Tore.



Having many children and youths as visitors every week requires a lot of hot water for showering. It takes a lot of energy to heat up this much water. During periods of extremely high occupancy we had additionally trouble producing enough hot water. This was when the idea of utilizing solar heat began to take shape. Our regular plumber had installed a solar heating facility for another client and he told us about this. Then we started our investigation and quickly found Free Energy’s website. After reading about Free Energy's unique hybrid solution which combine solar and geothermal heating there was never really any doubt that this was an ideal solution for us, says Tore.



Since we already had four energy wells we wanted to continue, Free Energy's HYSS system could be combined with solar collectors utilizing solar energy along with geothermal heat. Along with the installer and Free Energy we needed dimensioning a facility which could satisfy our demands. Calculations were made and the choice fell on HYSS. Solar collectors are now mounted on 3 buildings. 12x2msolar collectors are mounted on two buildings, while the last one got 10x2m2 mounted. Altogether there are 68m2 solar collectors at the campsite which are elegantly embedded in the roof and made concealed in a best possible way. They produce all the hot water we use for approximately 65% of our internat capacity. Additionally there are 4 energy wells drilled for contributing to the heating. The combination of solar and geothermal energy has been a huge success, tells Tore.



The facility is installed by VVS Rørlegger’n i Tønsberg AS. They are responsible for the technical part if anything should happen, but so far everything has worked according to plan. The facility requires minimal maintenance and solar heat and energy wells are in principle perpetual. We monitor and adjusts the system ourselves. We had good assistance from from Free Energy with training in the system application, which by the way is updated automatically via internet. Brilliant and super easy seem Tore. We've provisionally only been in operation since April this year, but the HYSS facility has really performed as expected. Today, July 7, it is bright sun with us and the facility displays measured temperature at the solar collectors at incredible 1200C, but we actually measured 600C also at the end of March, says a satisfied Tore. At the beginning we checked the temperature several times a day to see the facility’s performance, but now we check every week, Tore laughs. We are also required to log what the system delivers in order to receive the financial funding we were granted from ENOVA



Our HYSS facility, including installation, has a cost of NOK 2,2 millions, tells Tore. From this we have funding commitments from ENOVA of NOK 709,000,-. We’ve received 80% of this, while remaining 20% will be paid when submitting the final report with logged performance from HYSS. We expect to save about NOK 100,000 - in annual energy costs, says an optimistic Tore.



With the HYSS facility in operation, we are practically self-sufficient with hot water and heating for approximately 65% of the internat capacity here at Knattholmen. A vital point for us is in fact to promote and market ourselves as a green campsite. Although it is very important to save energy costs it is also important to visualize the environmental account for the facility. Our CO2 accounts look very pleasant after the inception with HYSS.


Anyone who visits us, especially camps students, get a tour of the facility with an explanation of how we utilize both solar and geothermal energy for heating and hot water. Everyone thinks this is both useful and educational, and it is important to inform and teach the next generation about this, tells Tore. We're very proud of our facility and what we have accomplished.


Others have also shown great interest in our HYSS facility and the installer has at several occasions brought costumers, both municipalities and others for a guided tour and introduction to how we utilize solar and geothermal heating in this unique hybrid solution. Even NRK have been visiting and made a TV report which can be viewed at NRK Vestfoldsendingen, concludes a satisfied Tore Nicolaisen.




Facts about the facility:

Type of house / Facility

Campsite, 16 buildings, 3 w/solar collectors


1937, expanded significantly over the past 30 years, latest building completed 2016


ca. 1100 m2 heated by HYSS

Annual visitors:

ca 6 000


Sandefjord municipality

Roof pitch:

200 and ca 30o (gable roof) - Facing south

Heat distribution:

Waterborne heating in floor of the new building, radiators in existing buildings

Facility outgoing heat:

40 0C (Floor)/ 550C (Radiators)

Indoor temperature:


Previous heating:

Ground heat, air-air heat pump and electric (Consumption 2015: ca 455 000 kWh)


4 new boreholes made for HYSS, 2x160m, 1x220m og 1x240m

HYSS heat pump:

3 pcs á 12 kW

Area solar collectors:

34 pcs á 2 m2, tot. 68 m2

Facility SCOP:

5,2 for both heating and hot water

Facility startup:


Reduced CO2 emission:

3 201 kg (since inception up to 07.13.2016)


VVS Rørlegger’n Tønsberg AS

Image gallery