Heating and low carbon technologies

According to the NHBC publication 'Homes for the 21st century' construction process consist of 4 levels.

First three processes was discussed on the previous posts. The following stage after all the planning, fabric, overheating, ventilation etc problems have been considered, is heating and low carbon technologies. The purpose of this last section is to reduce the energy savings on heating the space and water. Thus, the better house is insulated the lower demand for heating energy will be required. Also, according to the UK Government's set targets, the CO2 emission needs to be reduced as well. Hence, to complete both requirements low carbon technologies should be installed when building new dwellings or refurbishing the old ones. 

These tables shows the consumption of hot water and time water is heated per hour in a single dwelling. It leads to the conclusion that the largest demand of water is between 7am to 11am and 4pm to 8pm. This, also, means that on those hours the biggest amount of energy will be required to heat the water and it will take longer to heat the cold water over and over again. The same with the space: the bigger the space, the more energy and time will be required to heat it.  However, all  new build and refurbished homes could benefit from the use of low temperature water systems fed by heat pumps or condensing boilers which supply heat more efficiency, renewable solar energy,

underfloor heating systems which heats the space faster, etc.

Condensing boiler

The main working principle is to heat the water with the energy which is emitted as the hot gasses goes through a heat exchanger and cools and condenses them. This, also, reduce the heat loss.

However boiler works efficiently only if the flow and return temperature is kept below 55C. Thus, it is a good back up heating system combined with other.

Solar water heating (solar thermal) system

It consist of solar panel (collectors) which might be mounted on the pitch roof or be fixed to the frame on a flat roof, hot water cylindeer, pump and controller. The solar panels collect the heat from the sun which is passed to the fluid inside the collectors. Then  it is pumped to  the hot water cylinder, where the cold water is heated up and pumped to the taps. This system is the most effective in summer period when it is possible to heat about 90% of hot water use. However, the boiler still be needed to back up system.

Heat pumps

Ground source heat pumps

Heat from the ground is extracted from the underground by pumping water mixed with anti-freeze through it. Then the temperature of the fluid is increased by the heat pump and the water is passed to provide home heating (usually underfloor heating or radiators) or hot water (boiler).  

Ground source heat pump is quite expensive and it requires excavation and a good knowledge of the site ground condition to install. Pipe work laid out horizontally about 1.5m below the surface or vertically in boreholes between 20 - 150m.

Air source heat pump

The pumps are placecd outside to collect the the heat prom the air. Then, the air pump increase the temperature and pass the heat to radiators or underfloor heating system. 

Both heat pumps need energy to run, however it is still energy efficient as pumps use less energy and emit less CO2 into atmosphere to produce heat than it would be provided by burning fuel.

There is many other new technologies and energy efficiency strategies from which sustainable homes could benefit such as solar panels, rainwater harvesting system, wind turbines etc. Sometimes it may look expensive and difficult to install and maintain it, but if the manufacturer instructions is followed and automatic control system is used the results should be seen in a short period (reduction of energy use and bills).

Case study

Greenwatt Way development has number of features focused on energy strategy to meet the Code level 6 for sustainable houses. This includes, MVHR system; rainwater harvesting and grey water recycling systems to provide water for toilet flush, irrigation and car washing; solar panels which provides renewable electricity for homes; air source heat pumps, ground sours heat pumps, biomass boiler, which all three of them works independently to demonstrate it can work separately and generate enough heat to fit the zero carbon standards; smart metering, etc. 

References:

'Greenwatt way' [Online] Availabe at: http://www.thisisconcrete.co.uk/home_page/case_studies/greenwatt_way.aspx [Accessed at 17th of November, 2013]

‘Greenwatt Way. A zero carbon homes newbuild case study’, 2011. Energy saving trust.

 ‘Greenwatt way’ [Online] Available at: http://www.house-builder.co.uk/documents/WILFORD-Chris.pdf [Accessed at 17th of November, 2013]

‘Greenwatt way’ [Online] Available at: http://blog.emap.com/footprint/2011/10/13/a-visit-to-prps-greenwatt-way/ [Accessed at 18^th of November, 2013]

Energy saving trust, 2011. ‘Here comes the sun: a field trial of solar water heating systems’. 
Energy saving trust, 2010. 'Getting warmer: a field trial of heating pumps'

Solar Energy UK, 2013

Few weeks ago I started my second year in Architectural Technology course in Birmingham City University and the first project was about sustainable houses. After I heard the assignment brief I knew that one of my key point will be solar energy.  Such uncharacteristically sunny summer left a great impression, I think, not only for me but for most people who had a thought to go a bit ‘green’ and use renewable solar energy in their house as well. Sadly the Solar Energy exhibition was after my project deadline. However, I still couldn’t miss the opportunity to gain more knowledge about renewable energy as I am sure it will be closely related with my future career.

The exhibition took place in the Birmingham NEC arena on 10th of October, where I and my colleague were greeted by welcoming staff. To admit my knowledge about solar panels was not very impressive. Nevertheless, after few hours we had spent there and all the leaflets I read (and took home) I could say that now solar panels are a little bit more familiar to me.

Solar Panel

I found out that there are so many different types and styles of solar panels and to pick the right one is not as easy as it might seem. There are a lot of criteria such us, location, roof type, direction the roof is facing, use of energy: solar water heating or solar electricity etc. Also, there were talking about solar farms, its profits for the owners and how to fix, secure and clean the solar panels.

Inventor

Even though the solar panels are not such an old invention but its technology is improving so fast that it is a bit hard to keep up with it. Today was the first time I have heard about Solar Thermal Tube Panel (more info here), about the appliances for monitoring and managing PV work (some had such an elegant and great design that I felt necessity to get one, unfortunately, first I need to get PV) etc. SMA company attract my attention with Sunny View the device to track the plant data which shows not only how much energy it made, money you saved, weather forecast but also number of trees which would be necessary to avoid the same amount of CO2, it converts the amount of greenhouse gasses avoided into a car trip around the world and more.

Solar power borehole pump

To sum up, I think the exhibition was really successful. The show hall was quite busy even though we visit it on the last day. I am happy I haven’t missed the chance to gain more knowledge about solar energy.