WT4026/36 Blog

  Passive Design The Movement of the Sun The sun rises (morning) in the east and sets (evening) in the west. The sun is approximately due south at noon. The sun is higher in the sky in the summer then in the winter. Summer days are long; winter days are short. Solar Heat Gain Solar gain, also known as solar heat gain, is the term used to describe the increase in temperature in a space or material that results from solar radiation. The amount of solar gain increases with the strength of the sun and the ability of the material to absorb the radiation. Dark-coloured, rough-textured objects absorb solar energy, holding the heat. Light-coloured, shiny objects do not absorb the heat as good as dark rough objects, but they reflect the light far better meaning your room will become a lot brighter. Optimising Solar Gain in the Home Homes designed to optimise solar gain have 3 features: A façade that faces South. Lots of glazing in the south-facing façade. An interior layout that positions t...

    Passive Design Heat Gains Solar Heat Gain is the heat energy we get from the sun which will enter our homes through the windows. Internal heat gains is the heat we gain from things inside the home like body heat, cooking, anything at all within the building that produces heat, including small amounts like from a hair dryer for example. Heat Losses Heat is lost from the building through conduction through the buildings external surfaces, known as transmission losses, which we calculated previously in our U-Values. The other way it is lost is through air, the air inside is heated and when we lose this hot air we lose the heat, this can be lost through ventilation. Our Goal is to achieve a balance between these Gains and losses, like seen below. Space Heat Demand In the above image you can see in order to bring the building into balance an additional source of heat is required, demonstrated by the radiator. This additional heat requirement is referred to as our space heat dem...

    Passive Design Solar Energy The blue bar in the above sketch represents Solar panels which I will use to heat my water supply. Thermodynamic solar panels are reliable heating system. Providing year round water temperatures of 52°. Cheaper overall running costs. Environmentally friendly option. In theory,  thermodynamic panels  should  work  in all weather conditions, unlike solar PV or solar thermal systems.  The  panels  should still produce hot water in windy, wet or cold weather.  If positioned in the right place, they can benefit from some solar gain, but the  panels  are designed to  work  without it. Most systems come with a 5-10 year warranty but they last much longer up to  25 years .  Moreover, they require little to no maintenance, so the only expense you'll have to worry about is the installation cost.  Solar thermal panels can help you save up to 600 kg of carbon dioxide emissions in a y...

    Passive Design Heat Energy Average indoor temperature is 20° Average outdoor temperature is 10° The heat from inside the home is trying to escape to the cooler area which is outside. To prevent this happening we have to fully insulate our homes, but some level of heat energy will always escape through thermal conductivity. Thermal Conductivity thermal conductivity is the measure of the rate at which heat energy is conducted through a material. measured in watts per meter kelvin. when talking about thermal conductivity we are talking about a sample cubic meter of the material. The building regulations provide us with the thermal conductivity of common materials, seen below. Thermal resistance Thermal resistance is the term used to describe a materials ability to resist or prevent the flow of heat. the thermal resistance of each material depends on its thickness and the rate at which it can conduct heat. Surfaces resistances In construction studies we use standard values for...