Heat Pumps collect heat from the environment (e.g. air/ground/water) and are ideal for the Irish climate.
They are an excellent energy source for underfloor heating in particular.
Heat pumps use a small amount of electricity to upgrade the heat gathered from the environment to a usable level indoors. Installation costs are similar to those of a conventional heating system but running costs are much lower.
How it works
The earth’s surface acts as a huge solar collector, absorbing radiation from the sun. In this country the ground maintains a constant temperature between 11oC and 13oC, several metres below the surface. Heat pumps take advantage of this by transferring the heat stored in the earth or in ground water to buildings in winter and the opposite in summer for cooling. Through compression, heat pumps can ‘pump up’ heat at low temperature and release it at a higher temperature so that it may be used again. A heat pump looks similar and can perform the same functions as a conventional gas or oil boiler, i.e. space heating and sanitary hot water production. For every unit of electricity used to operate the heat pump, up to four units of heat are generated. Therefore for every unit of electricity used to pump the heat, 3-4 units of heat are produced. Ground source heat pumps use a 'closed loop' system of water/anti-freeze to collect the soil heat. Air/water heat pumps collect heat from the outside air. Generally, air temperatures are moderate in Ireland but due to natural frosting of the air heat exchanger during heat collection, it is necessary that these pumps use a small amount of energy to defrost. This leads to a marginal decrease in performance which is offset by a low installation cost. Water/water heat pumps use water from a well/river directly as a heat source. These are generally 'open loop' collectors, i.e. the water is passed through and discarded, unlike the 'closed loop systems'.
Installation in the Home
The system has three main components: a series of pipes in the ground, a heat pump and a heat distribution system. Lengths of plastic pipes are buried in the ground, either in a borehole or a horizontal trench near the building to be heated or cooled. Fluid, normally water with anti-freeze, absorbs or emits heat to the soil, depending on whether the ambient air is colder or warmer than the soil. In winter, the heat pump removes the heat from the fluid, upgrades it to a higher temperature for use in the building, typically in under-floor heating. A distribution system is needed to transfer the heat extracted from the ground by the heat pump.The heat is often in the form of hot water and is distributed around the dwelling by radiators or a low temperature underfloor heating system.
Payback and Maintenance
The initial capital costs of installing a geothermal heat pump system is usually higher than other conventional central heating systems. A large proportion of the outlay will be for the purchase and installation of the ground collector. The system is among the most energy efficient and cost effective heating and cooling systems available.
Typically, 3-4 units of heat are generated for every unit of electricity used by the heat pump to deliver it, and the payback is typically about 8-10 years. The life expectancy of the system is around 20 years. Once installed a heat pump requires very little maintenance and anyone installing a heat pump should speak with their installer regarding a maintenance agreement. Heat pumps operate optimally when a system design approach is taken. It is important that the heat collector and heat distribution systems are correctly sized/installed.
Using wood fuel instead of peat, coal and gas to heat our homes is a sustainable choice, and makes a positive contribution to the environment.
Wood is ‘CO2 neutral’, the amount of CO2 wood releases during burning is equal to that which is absorbed during growth. In contrast, burning fossil fuels releases the global warming gas carbon dioxide, as well as other damaging pollutants.
Wood fuel also takes just 5-20 years to grow, whereas peat and coal were formed over hundreds of thousands of years.
Modern, highly efficient stoves and boilers make wood fuel a practical and sustainable option for today’s lifestyle.
Choosing a wood stove : when and why, what type? Wood stoves - general A stove, in general terms, is a heating appliance that is designed to give heat directly to it’s immediate surroundings, i.e. the room in which it is installed. All stoves have a transparent front which releases approximately 20% of the heat produced to the room in the form of radiant heat. Radiant heat is also the type of heat we receive from an open fire. A room heating (or dry) stove will distribute the remaining eighty percent of the heat to the room via a hot air fan at the top of the stove, whereas a stove with a back boiler (or wet stove) will use the remaining eighty percent of the heat for heating radiators and hot water. Wood pellet stoves Wood pellet stoves offer convenience by way of automatic pellet ignition and a built-in fuel store at the rear of the stove. This store or “hopper” generally ranges in size from thirty to sixty kg approximately, which is enough for one to two days running during a heating season, depending on the stove size. It is important that you source a quality supply of wood pellets for a reasonable price. For a wood pellet stove you generally require less pellets per year in comparison to a full wood pellet boiler, and so buying in bag form might be more suitable, especially as you will need to bring the pellets into the room to fill the hopper full of pellets. Wood pellets must be kept dry (approx. 10% moisture content), and bagged pellets offer this advantage straight off the shelf. Remember also though, that bagged pellets cost more than pellets delivery in bulk (approximately forty to forty five percent more expensive per kg). Look for the wood fuel quality mark (WFQA) , or equivalent, for peace of mind regarding wood pellet quality. Wood log stoves If you have a steady source of wood logs available, then a wood stove might be a suitable option to investigate. Wood log stoves are slightly more labour-intensive their wood pellet counterparts as the firebox must be manually filled and manually ignited when required.
Solar panel refers either to a photovoltaics (PV) module, a solar hot water panel, or to a set of solar photovoltaicsmodules electrically connected and mounted on a supporting structure. Solar panels can save you up to 70% on hot water costs, while upgrading your heating can save you up to 50% on fuel costs.
THERE ARE TWO MAIN TYPES AVAILABLE:
Flat Plate Collectors: Building-mounted flat plate collectors can be positioned both "in-roof" and on-roof due to their structure (heavy, rigid, robust box-like structure). The efficiencies of flat plate collectors make them very suitable for domestic installations or for installations where very high temperatures aren't required. They are often considered to be more optically appealing due to their flat surfaces, but this is a matter of personal choice.
Evacuated Tube Collectors: Building-mounted evacuated tube collectors can only be mounted on-roof due to their lightweight structure, which is most commonly individual tubes monted on a frame. On average, an evacuated tube collector will provide approximately 20% more yield per m2 of aperture area than flat plates, which means that less installed area is required for similar heat outputs. High efficiencies from low radiation and high temperatures (very useful where high temperatures are needed in process/industry)
There are other categories of solar collectors which you might encounter, and most of them fall within the flat plate or evacuated tube categories above. Efficiencies vary from collector to collector and the main effect that the efficiency will have is on the amount of installed area required, i.e. the more efficient the collector the less installed area required.