How Do Heat Pumps Work

Post occupancy: is your building really so green?

Nowadays buildings with natural ventilation, biomass boilers or ground source heat pumps are standard stuff. Understandably, most people assume that low-carbon build methods and tougher energy regulations mean buildings use far less energy than ones built a few years ago. But do these buildings use less energy? Does natural ventilation work when you are relying on people or complicated mechanical systems to open and close the windows? Are those anecdotal stories about biomass boilers continually breaking down true? Are ground source heat pump systems too complex for their own good? The reality is that only a handful of people know the answers, meaning most are designing low-energy buildings in a vacuum. Monitoring buildings for post-occupancy energy use is time-consuming and expensive. And if the money is found and the results aren’t flattering, then the results are unlikely to get past the building owner out into the public domain.

Now Building can shed some light onto this difficult issue. We have teamed up with the Carbon Trust and BSRIA to bring you the true story of how well low-energy buildings really perform. The Carbon Trust administered the government’s low carbon building programme, which funded a range of low-carbon technologies. It also advised on a range of energy efficiency measures. The buildings that benefited from this programme have been monitored for a minimum of a year after completion by consultants including Aecom and Arup. BSRIA’s Rod Bunn, who was behind the PROBE series of post-occupancy evaluations in the nineties, has waded through boxes of raw data and number-crunched it into shape. In the first of two features we look at two new build, low-energy office buildings to see what Bunn found.

This office in Aberystwyth is typical of many recent good practice low-carbon buildings. It is mixed mode, meaning it is naturally ventilated with backup mechanical ventilation and cooling for very hot days or when the building gets stuffy in winter. Elsewhere it utilises energy-efficient lighting with solar thermal panels for hot water and there is a wind turbine too. The aspiration for this building was carbon emissions of less than 50kgCO office is occupied by Ceredigion council and has a BREEAM “excellent” rating. It consists of a three-storey and a four-storey wing sitting on either side of a central, full height atrium. Most of the building is open plan offices with some cellular accommodation on the ground floor.

How air source heat pumps work

An air source heat pump works by extracting heat from the outside air in the very same way a fridge does.  The only difference is that it uses an external heat exchanger to heat the refrigerant. As heat naturally flows from a warmer place to a cooler place, heat pumps use refrigerant that constant evaporates and condenses in a closed circuit.  This closed circuit is controlled by valves and a compressor in order to reverse this natural process. They can be used to heat the radiators and under floor heating systems as well as the water in your home. Heat pumps are not completely green as they use electricity to run, however the heat that is extracted is constantly being renewed naturally.  Compared to other electrical heating options heat pumps use less electrical energy than the energy they create, so they are still a greener option. Using an air source heat pump can lower your fuel bill, reduce your carbon footprint and there is no need for fuel delivery.  You will be providing space heating and hot water. If you're interested in having an air source heat pump installed in your home you need to find a place to store it.  They go outside your house and can be fitted to a wall or can be self standing.  Your home should be well insulated as they work better at low temperatures, keeping a constant temperature.  With homes that are not properly insulated, this heat will not be enough keep your home warm, plus any heat generated will be lost. The costs for installing can be quite expensive.  Between £6000 and £10,000 is about average currently.  They are becoming more and more popular in the UK and have been in other established EU countries for some time. There is plenty of information about heat pumps on the energy saving trust website.  Plus many central heating companies are now turning towards renewable energy and are installing these and other green systems. So-called source heat pump, is a kind of sea water as the heat source is designed and configured for heat pump heating systems and devices, is a different heat pump configurations, only the selected use of different heat exchange. The so-called special, just for the water quality of different materials with different (anti-corrosion) heat exchanger (evaporator and Condenser ), Etc.. If by now you have been known to the "water pump" the concept of classification Channel Recommendation: PHNIX-Fennikezi Cup 2008 Ten selection feature air conditioning and refrigeration Channel Recommended: 2008 year-end inventory of HVAC industry Abstract: Currently, ground water source Heat Pump Air-conditioning system, often a deep well of water supply to meet the required two or more of water heat pump unit. However, in actual operation found that most of the time heat pump part load operation, while the deep well pump has been running at full capacity Early summer in May, is to be congratulated McQuay season, following the McQuay air-cooled module efficiency at the national level unit MAC-XE series of shock after the listing, but also a "benchmark" products - Modular Air Source Heat Pump MHA sparkling water unit listed. As people's living standard rising, hot water production has become an important daily living conditions.

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