Saturday, 14 July 2012

Sustainable Retrofit Essay

This is definitely just for archival purposes... here is the essay which went with the previously posted assignment. Oh man, I'd really like to rewrite this now... this was the last part of the assignment I did, so I was a bit pushed for time... still, I think this could have been a wee bit better, although I was happy with the final grade.

Also, this was more of a paper explaining the project rather than an essay-essay type essay, if you get what I mean... :P


The existing home has been retrofitted for a typical family with two adults and two children. It uses passive systems to make it resource autonomous, and aims to expand the ecological base and increase the public estate. These changes should improve the home’s natural support systems and the life quality of its occupants, as well as reverse the on-going impacts of past systems design.

Prior to its retrofit, the existing building required a connection to a centralised grid for electricity and waste management, and used fossil fuels for heating and cooling. This was not net-positive, and it is important that housing should provide thermal comfort through natural means, such as solar access, wind protection and natural ventilation. (Robert Moore, 124)[1] Therefore, the use of passive systems has been incorporated into the existing design to make it resource autonomous and to give back to nature more than the building has taken. This goes further than what is currently considered as ‘sustainable’ development, which has so far only aimed at reducing the impacts of conventional design.

Convection, conduction and radiation of heat have been considered when implementing passive systems into the existing design. The size of the windows on the front façade has been increased to allow more sunlight to enter the building. They have been fitted with vinyl-clad and aluminium-clad exterior frames, which are currently seen as a good balance between low-maintenance aluminium frames that have high-embodied energy, and wooden frames which are high-maintenance.  The solar chimneys make use of natural convection to cool the home with cross ventilation. Warm air rises through the house and is replaced by cool air at the base of the house. The solar chimneys have been painted black to cause the chimney area to be hotter. Moreover, the air rushing in and out of the solar chimneys aids natural winds in working the urban wind turbines.  These, along with the photovoltaic panels on the roof and front façade of the building, provide energy to power any electrical appliances the occupants may wish to use. This means that the building will no longer require a connection to the centralised electrical grid.

Similarly, the use of trombe walls, thermal masses and effective insulation mean that no fossil fuels or electricity will be required to heat the building.  Trombe walls are a cheap way of heating large spaces. On the northern façade of the building recycled glass has been placed 15mm away from the walls to create a trombe wall. This traps the heat provided by sunlight hitting the glass because heat is re-radiated by long-wave radiation, which cannot pass through glass. Vents at the top create a convective current, which provides warm air when needed. Trombe walls have also been used on the interior of the building. A dense material is placed near to the skylights above the bathroom and laundry. This acts as a thermal mass, storing heat collected and recirculating it later, when needed. Moreover, trombe walls can be designed to have other functions as well; the trombe wall in the bedroom and office area serves the double function of acting as a thermal mass and as a shelf. This is a more effective use of space and also more resource efficient, as the shelves are constructed out of recycled bricks. This means that the trombe wall will have less embodied energy than if it was constructed out of new materials. The combining of these systems means that fossil fuel and energy is saved, since you don’t need to heat and cool the building; it does it itself.

Moreover, water tanks can act as thermal masses. The exterior water tank also acts similarly: putting a water tank against a wall causes it to act as a thermal mass, therefore as insulation. It also collects rainwater, both falling from the sky and any that is not absorbed by the greened roof; this water is channelled into this water tank and the vertical plant boxes on the green wall beside it. These boxes then filter the water before it is collected in the pond beneath the kitchen window. Similarly, the water tank in the sunroom, not only provides water for drip irrigation, which can save 90% of water and delivers the right amount of water to the base of plants, to the interior green wall; it also stores heat collected in the sunroom. These thermal masses, combined with effective insulation, prevent heat from escaping the building.

It is important that the occupants do have some control of their heating, however.  Dehumidifiers in the bathroom and ceiling fans use electricity generated by the photovoltaic cells, urban wind turbines and kinetic energy converting children’s swing set to cool and ventilate the building. They can also let more heat into the building as easily as opening the sun room door. This means that while most of the buildings systems do not rely on an occupant to control them, it still gives the occupants chances to regulate their own thermal comfort.

The comfort of the occupants is also increased through their access to greenery. Not only do people have biophilia; a need to be around nature, plants improves air quality by sequestering CO2 gases, emitting O2, and filtering particulate matter in the air. Studies have shown that living near plants can reduce stress levels by 20-40% and severe violence by 54%. This means that the occupants of the building, as well as anyone who spends time near the site, will be healthier and happier. Greenery is also implemented in ways that will make the occupants feel more noticeably comfortable. Custom made chairs have hydroponic plants growing out of their backs, which receive water from pipes that travel up through the chair. The pressure of the water travelling through the chair will create a pleasant massaging effect for whoever is seated in it.

Furthermore, plant life can also filter water and treat waste. Dissolved substances like nitrogen and phosphorus can enter out water if not treated by plants. Being treated later may be too late. Planter boxes placed vertically above one another create green walls that filter any overflow from the gutters. Holes at the bottom of the planter boxes allow water to seep through to the next box, where the water will both benefit the greenery planted there and be filtered by the time it reaches the bottom. There it falls into the pond created there and reflects sunlight into the rooms. Toxins from kitchen grey water are filtered out in the aquaponic box on front of the window before being pumped up to the top of the roof to be used as the water source for the greened roof’s drip irrigation. The composting toilet treats black water and can create good worm farms and nutrient-filled soil for the garden. It includes a separate urine collection, so that the urine can be used for the garden and poo for the compost. However, when the urine is broken down into ammonia by the bacterium micrococcus urea, this can cause smells. Therefore a small inline fan established draughts down the pedestal and removes odours. Similarly, a flowerbed is planted around the living machine used to treat from both the home and the next-door hospital. This decreases smells and, together with the fishpond at the end of the living machine, creates an attractive landscaping feature. These decentralised systems mean that the home no longer needs to be connected to the central grid which is beneficial because centralised chemical water treatments lead to ever more resistant microbes and pathogens with an increased risk of disease. This can be very costly.

Moreover, green walls and roofs can also act as insulation and cool structures as well as reduce storm water run-off Greened walls and roofs act as a protective, insulating layer on the building and provide natural, evaporative cooling. As warm air above hard surfaces rises it is replaced by cooler air from above the vegetated roofs, creating an urban ‘sea breeze’. (Osmond, 101)[2] They also filter and cool down the water that slowly runs off. This, similar to the line of tree pits which follows the perimeter of the site, delays and reduces storm water. This is a positive development since only some of 15-20% of incident rainfall evaporates on impervious surfaces, whereas the rest is lost to storm water drains. Green roofs retain a significant proportion, 40-70% of rainwater, depending on the season, soil depth and slope. This also partially restores the natural water cycle and means that flooding and property damage in cities can be reduced.

Urban food production and habitat restoration is also possible with greened roofs and walls.  Since the Industrial Revolution, the trend to separate cities from their sources of nutrition has spatially and psychologically distanced urban dwellers from the land. Yet herbs and vegetables can be grown on the greened roof and walls of the building, as well as the vegetable patch in the garden. This also creates a social benefit for the family, who can work in the garden together, as well as explore the play garden. Moreover, displaced wildlife can use these greened walls and roof as a vegetative patch. Layers and edges create biodiversity, which is a principle of permaculture. Greened roofs and walls can also redeem the feeling of natural seasons. Essentially, the greening on the roof and walls mitigates high-density development and creates positive impacts.

Therefore, the existing building has been retrofitted to be net-positive. It is resource autonomous as it creates it’s own electricity, heats and cools itself and treats its own waste.  The greened walls, roof and landscaping increase social and natural capital and benefit the home and surrounding area in a number of ways, meaning that it is more resource efficient. Human health and happiness is improved as well as ecosystem services. The home has net positive developments; it expands the ecological base and the public estate.

[1] Robert Moore. "Box 14 Adaptable Housing." Design for Sustainability: A Sourcebook of Integrated, Eco-logical Solutions. By Janis Birkeland. London: Earthscan Publications, 2002. 123. Print.
[2] Osmond, Paul. "5.2 The Sustainable Landscape." Design for Sustainability: A Sourcebook of Integrated, Eco-logical Solutions. By Janis Birkeland. London: Earthscan Publications, 2002. 101. Print.

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