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The report is about a low carbon building dwelling by two residents.The area where the house is going to be built is inside Brighton's University campus of art, in Grand Parade street. Average seasonal temperature, seasonal and daily solar radiation, are going to be calculated because they influence the energy consumption (Lancashire & Pitts, 2011). It is mandatory, in order to avoid large costs of installation, to understand the site layout and make decisions early to have a major effect on total energy efficiency. In this survey the construction area is surrounded by high buildings in all orientations except from south where is the main area of interest because we are going to install photovoltaic panels and solar thermal collectors. The aim and the objective of this study is to build a house with low carbon emissions that leads to less energy consumption and more energy efficiency. Fossil fuels must be limited to minus. Visiting eco-houses and studying resources referring to low carbon buildings, ''earthship'' buildings and in general eco-structures helped to understand and interpret the definition of a green house.
2. Definition of a low carbon house and its interaction with the local environment
Heat and hot water for houses and workplaces is created from renewable energy sources within site boundaries. A building fabric achieves a step change reduction in the need for heat and power, making it possible to harvest a high percentage of passive energy. Enough electricity is generated from renewable sources within the site boundaries to match the annual electrical demand for the entire live work community. Overall annual CO2 emissions to atmosphere are zero; biomass is considered to be carbon neutral (Hewitt & Telfer, 2007). There are key areas that been measured as it concerns the site, the environment and the surrounding where the sustainable building is going to be construct. Air quality and ventilation are important for the indoor environment and can have a negative impulse into HVAC (heating, ventilation and air conditioning). Polluted areas near the house (such as a landfill) can damage the indoor air quality by introducing contaminants. Thermal comfort affects the tenants and the indoor environmental quality (IEQ). The local environment has minimum impact on thermal comfort. Acoustics and noise are also an important aspect in determining good indoor environmental quality (IEQ). Satisfactory Lighting levels are compulsory for the building residents and vary according to the design purpose of the room. The local environment can have trees, buildings or other obstacles which affects solar radiation to enter and diffuse properly into the building. Visual perception is another area that influences how a residence perceives the IEQ. The project architect will have to deal upon that crucial area (ASHRAE, 2006).
Brighton's climate is oceanic like most of the southern Britain. Summer is normally pleasant, maybe some heat waves with temperature around 30 degrees. The highest temperatures are in July and August with an average of 17 degrees. Winters tend to be like most of the southern England; though through easterly outbreaks, snow is common. January, February and December occur the lowest temperatures with an average of 5 degrees. The maximum sunshine is from May until August for 7 hours a day in average. Rainfall's pick (approximately 21 days a month raining) is from November till January with values from 8cm to 11cm.
3. Building materials
Usage of low effect materials in building, passive solar design for space heating, energy efficiency and renewable energy sources for daily electrical and hot water demand, and water conservation measures including rainwater harvesting for water supply and onsite wastewater treatment and recycling, using plants to filter out impurities (Hewitt & Telfer, 2007).One of the primary aims in the construction of a low carbon building is to reduce the energy which is embodied to the materials. This idea is using a wide range of waste materials such as reclaimed timber and masonry to used car tyres, recycled glass bottles and tin cans. The house is a timber frame construction where all the structural members are going to be of timber.
Walls are having wool insulation. The external walls, which are extremely important in terms of total building loss and so energy efficiency, will have a stud depth of 140mm( strength graded softwood) in order to supply a good insulation and stud spacing between 400mm and 600mm.Wool insulation by moderately flexible quilts or batts of mineral have been used for timber frame external walls. For a better passive solar heat is recommended to increase thermal mass to external walls. This can be succeeded by supplying with extra mass the internal linings by adding layers of plasterboard or denser boards (need more space) to the southern rooms. Mineral wool in internal walls will provide sound insulation as well as thermal. Similar to external walls, thermal mass will be increased by adding layers of plasterboard or denser boards in rooms southern orientated. Party walls are provide sound insulation and also act as thermal insulation by decreasing heat loss to the partly cooled party wall cavity.
The type of roof that is going to be installed is a "warm deck inverted flat roof with insulation above the waterproof finish" (Lancashire & Pitts, 2011). U-values are between 0.20 and 0.15 W/m²K. A waterproof membrane is the roof finish. A ventilation system is not required since the membrane works as a vapour control layer (Lancashire & Pitts, 2011). A rooftop garden; eco-roof, will be constructed with a variety of plants such as hearty wildflowers and shallow-rooting grasses. Ground cover can thrive in a relevant shallow soil with the advantage of little maintenance. (Wark & Wark, 2003).
Ventilation and airflow are needed for consedation control and fresh air. The ventilation system must be adequate but not thorough to prevent extensive heat loss. Entrances should be placed away from prevailed winds and in consequently a draught lobby is an extra protection against heat loss. Windows specifications include a slot ventilator in the top sash for a draught free ventilation in the winter (Lancashire & Pitts, 2011).Windows will be triple glazed in order to maintain more heat inside the house with a U-value about 0.65 W/m²K. Triple glazing is extensively used in countries with a cold climate and passive houses with ultra-low energy standards.
4. Renewable energy sources and monthly supply profiles
Green houses are using natural phenomena for their advantage, as the wind or the rain, to fluently achieve its goals. Solar radiation stands as one of the best accessible renewable energy resources thus PV power production is characterized by little power density which is associated with the radiation from the sun and low conversion efficiency. An efficiency close to 15% can be provided by an affordable technology (Cristaldi, et al., 2012).
4.1 PV panels
Photovoltaic panels are going to be installed on the roof of the building for space heating. The best angle for maximum energy efficiency is 30° to 45° south orientated. Panels for having ideal performance have to be cleaned and not to be overshadowed (e.g. by trees).In United Kingdom due to rainfall, is beneficial to tilt the panels at 15° or more. The PV panels construction model will be by Monocrystaline cells from a single crystal of silicon. As it concerns the appearance, will have a plane texture and the thickness of the silicone's slice will be visible. For protection cells must be mounted by a rigid frame. This type of cells is the most efficient for our construction but the most expensive too. The system that is going to be installed is 2kW, with 12 PV panels to an approximately 16.4 m² area. Inside the house walls, electric radiators will be mounted for space heating. The solar energy will be converted into electrical for the radiators to operate. The panels will generate close to 1800 kWH per year producing about the 60% of the electricity demand. Beginning of November to the end of February the average electricity production is going to be between 35kWH and 90 kWH. Additionally from March until October the values are expected to be between 100kWH and 230 kWH. During the year, there will be days where is mandatory to export unused electricity to the grid (The solar trade association , 2012). Cloudy days the electricity will be generated from the grid.
4.2 Solar thermal collectors
Moreover, vaillant solar thermal panels will be mounted to the roof, southerly orientated with a slope between 35 to 40 degrees horizontally. They can exploit the sun's power in both direct and diffused sunlight. They can fit well with a solar coil cylinder.These panels will generate approximately 1200 kWH annually. They meet the demand for a 55% of hot water demand in a year thus the other 45% will be generated by a secondary boiler days with low solar emission. As in photovoltaic panels, the average monthly values are low between 30kWH and 80kWH from November to March in addition to higher values from April till October ranging between 80kWH and 160kWH.
4.3 Green roof
The building will have a green roof as an environmental friendly and sustainable construction practice. Green roof helps by absorbing rainwater, providing better insulation, reducing heating and cooling. The main disadvantage is the primary cost of the construction, waterproofing systems and root barriers.
Regarding the lighting of the house, LED lamps will be installed. They are highly more energy efficient than those with fluorescent, halogen and incandescent. During the day, the light which produce depends on the amount of solar radiation diffuses around the house; more radiation the better.
5. Energy demand profiles
For a couple, the energy demand profile annually is approximately 7500 kWh. Most of the energy is necessary for space heating and water heating. Electric appliances in the house, such as oven, washing machine, personal computers, television and more, require less energy in total. In the winter months (December, January and February) energy consumption is the highest of the year as a large amount of electricity is mandatory due to low temperatures and lack of sunshine. The house has a very good insulation and ventilation leading to an energy saver profile which requires less energy to operate. From April until mid-October almost, average temperature and sunshine is better and consequently energy demand is relatively decreasing. The residents of the house should reduce the energy consumption and as a result the carbon emissions. The energy must be used in an efficient way and obtain the energy demand through the renewable energy sources of the building.
6. Energy balance, discussion and conclusion
Energy can escape the building's boundaries, where it is used. That is an energy loss. The necessity for space heating is the result of heat loss; an energy loss. To reduce the heat loss is required a good insulation that means appropriate building materials for constructing the walls, the windows, the doors and the roof. Heat can be gained by the solar radiation which infiltrates the window panes or by internal heat sources such as electricity supplies. This energy is well been transferred into the house. (Feist, 2006).The construction of the low carbon building in Grand Parade tried not to compromise economic, ecological and social priorities. Local materials are been used, like timber and renewable sources have been attached on the roof such as PV panels and solar thermal panels. Interior lightning of the building made by LED lamps to reduce cost and electricity demand. "United Kingdom has committed to reduce carbon dioxide emissions by 60 % before 2050 in order to help tackle global warming" (BBC, 2007). The construction of low carbon buildings is now becoming a necessity.
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