GROUP 5 - SPACE AND DOMESTIC HOT WATER (DHW) HEATING

- Biomass
- Geo thermal
- Sea thermal
- Solar thermal
- Transparent insulation
- Heat pump
- Fuel cell/hydrogen

Hot water, electricity or hydrogen is termed an energy carrier. They ”carry” energy, but the energy must be produced from an energy source. The energy source can be hydropower, coal, oil,solar, wind etc.

Hot water as energy carrier (radiators, underfloor heating etc) has often been recommended because it provides flexibility as to choice of energy source.

However, what is typical of the energy efficient dwelling concepts described in this web site is that they have a reduced energy need and the space heating need could in many cases be so negligent that it is difficult to defend the large expenses for the infrastructure needed if the need for transporting energy is extremely small.

Well designed energy efficient dwellings have hardly any need for an extensive heat distribution system like underfloor heating (infrastructure), except possibly in the bathroom for comfort and to dry out wet areas.

Well designed energy efficient dwellings have also eliminated cold drop (??) and draught and willprobablky receive a good price in the second hand market. This is also a reflection on the fact that such dwellings also have less technical gadgets that can go wrong.

Bioenergi

In many countries there is a tradition for using biomass like firewood. If the wood burnt a year is similar to the new growth of wood, firewood is CO2 neutral. Particles and smells are however still problems that are not eliminated in densely populated areas. People with respiratory system illnesses like astma and allergies have ahard time. It is hence only recommended to use logfiring that are burning the wood well which is the case with most of the new ovens.

Using pellets is another option. Pellets are dried and compressed woodchips that can be burnt I both large burners/boilers I large buildings connected to a water based heating system or in smaller units in pelletovens in individual apartments.

As a heating source ina low energy bulding a good pellet burner has only a few userdays. Overheating will hence occur in periods of such low heat demand if the oven with its fairly high capacity in spite of this is fired.

Geothermal

There are two types of geothermal energy.

One involves huge investments as it includes drilling far into the ground to reach warm layers. This is normally only done in large building developments.

The other is heat pump based, involves less investment and can be used in smaller housing schemes. It involves the mounting of cables under the turf (200-400m2 is normal for todays North European housing standard for one detached house). The heat pump uses the fairly stable 4 degrees C year round temperature at a depth of 0.6 to 1.5 metres. Sucha system could cover approximately 60% of the annual energy need fro space heating and DHW. Whether such a solution with its after all coinsiderable investment and extensive works is of interest in a low energy need building, is questionable.

Sea thermal

Oceans or lakes also have a stable temperature of minimum 4 degrees C throughout the year at a certain depth. This is again a good source for optimum operation temperatures in a heat pump.

The distance from the building to the source (water) should not be more than 100 metres to defend the costs. Again : buildings with very low thermal energy needs might not be able to justufy the delivery of small energy volumes from a costly investment.

Passive solar thermal

Passive heating from sunshine through the windows contributes towards heating any building. Simultanously, a challenge is shading when the direct sunrays create glare or overheating. In Northern Europe buildings with windows towards the sun (all directions except North) needs to buy 20 % less energy for heating annually compared to a building that have large windows facing North. This gain can however easily again be lost if the overheating challenge results in use of cooling systems. So the two contradictory issues (heating and coooling) must be well balanced.

Active solar thermal

Active solar thermal means heat that is moved by pump or fan from a roof- or wall integrated solar thermal system that uses air or water as a solar absorber medium. Solar warmed water or warmed air can be used either fro space heating or DHW.
In cool climates the space heating postion is normally the largest, but as buildings get more and more energy efficient this is turned upside down as the annual DHW component can become as big as the space heating need.
A typical solar energy supply (usable energy) from a solar system is in the region 200 – 400 kWh / m2 collector / year.

Transparent insulation

Plastic looking non-transparent element insulating well and works based on the greenhouse principle. Some products have a honeycomb structure. Transparent insulation gets warm on the inside as the sun shines, but the heat does not leak out again. It could be applicable as a supplier of low temperature heat or preheating of DHW. Architecturally the expression can be challenging, There are only a few products on the market.

(Vanskelig gjennomsiktig plastlignende men samtidig godt isolert element som fungerer etter drivhusprinsippet. Det blir varmt på innsiden uten at varmen lekker ut. Noen produkter har honneycomb struktur. Bare få produkter på markedet. Få er utprøvd i Norge. Interessant for lavtemperatur oppvarming av bygg samt bruksvann forvarming. Spennende arkitektonisk uttrykk – plastlignende men ikke gjennomsiktig. Som værhud brukes noen ganger glass ytterst.)

Heat pump

Several products available, in some countries a heat pump boom has been experienced. Experience with its use is that if the heat pump was suppoed to deliver heat in th eheating season and is also used as a new way of cooling in the summer, the energy/environmenat effect of installing it is reduced.

a. Air/air:

Noise can be a problem for bith the user and the neighbours in regions where one is not used to such machinere or air condition noise. Conflicts arise.
Indoor noise is low but unusual for those new to air condition.
Heating of dwellings by air / air heat pump is most applicable if there is an open plan. If that is not so, a lot of ducts will be needed and brings up the cost.

b. Air/water:

For DHW or space heating

c. Water- or geo heat pump

Plus 4 degees C minimum is normal at a certain deoth of lakes, sea and soil and a good source.

b. Grey water heat pump

Extracting het from warm waste water can be of interest provided the investment is not too high.

Fuel cell/hydrogen

Hydrogen is one of the interesting energy carriers in th future, provided the energy neede is renewable.

For more information go to the internet and search for sites of relevance using keywords like : heat pump manufacturers, solar energy heating system manufacturers, bio energy system manufacturers, hydrogen or fuel cell manufacturers, try all the relevant manufacturer associations with key words as above. Then add your country or region behind the search word if you prefer local products.