Residential Zero Carbon Dwelling Houses Project Study

"BedZED 2007" by Tom Chance from Peckham - flickr: BedZED. Licensed under CC BY 2.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:BedZED_2007.jpg#/media/File:BedZED_2007.jpg

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Sustainable Development of 60 Residential Zero Carbon Dwelling Houses Wardmill Industrial Estate, Arbroath, Angus, Scotland, UK 2014

TOPICS: Site History, Site Detail-Location and Site Plan, The Current Policy and Strategies, Aims and Objectives, Similar Examplary Projects, Design Principles - Design Guides, Design Solutions-Renewable Energy

Abstract:

The aim of this report is to design and illustrate sustainable, zero carbon housing development through using Passive House Principles and related design solutions for the Wardmill Industrial Estate, Arbroath.

Initially, the report examines the site detail in relation to the Angus Local Plan Review. The key issues facing the site will be revealed and the specified improvement strategies for this particular area will be discussed, including explanations of the area short history and ownership. The major site and area appraisals due to its specific points and identity will be investigated.

Afterwards, the report continues site plan, notional site section, floor plans and elevations of selected buildings. The diagrams and figures are included in the report and software programmes Ecotech, AutoCAD, Sketch-up are used to establish required illustrations. The primary principles of each design will be checked its availability for this particular area according to its approximate cost comparison, the manufacturers, return of the investment and the relevance to the low-energy, zero carbon or passive house methods.

At the final stage, the design solutions at the site will be shown and supported with figures, diagrams and visual illustrations.

Please note that, only the topics above added to this page.

HISTORY - Housing Development:

In the late 18th and 19th centuries, Arbroath has developed dramatically with the textile and general engineering advancement. By the increase in mills and industry workers, houses were constructed for the incoming workers. The material of local Old Red Sandstone used for the buildings in the ancient city. However, imported materials also were used in the housing units. For example, the form of grey stone roofing slates was brought from Carmyllie Quarries. (Angus Council Cultural Service, 1998, p1) Furthermore, Arbroath has great advantage to benefit from quarries for housing development on the basis of transportation of construction materials such as aggregate and limestone. There can be noted that the possible sustainable housing design solutions can be created inclusion by usage of local materials around Arbroath. This will reduce considerably transportation distance, as well as in relation to the CO2 emission caused by material transportation will be decreased. At the same time, the construction process will be operated faster and more economical.

The ancient vernacular character of houses can be seen near the harbour in Boatyard (Figure 2) and Oldshorehead (Figure 3). The number of outside stairs and stone-slated roofs are the remaining parts of old years implementations of dwelling units. There is one example of secular building which possibly the oldest architecture of the town is Newgate house. (Figure 4) The local red sandstone masonry work was covered all exterior sides of this building which was restored in the beginning of the 19th the centuries by Angus Housing Association. During the same years, as different from the harbour structure, ashlar facings, decorative guttering and stylish, elegant air was the identity of the Hill Terrace. (Figure 5)

CHARACTERISTICS SITE

This site is situated at the north site of Arbroath. The existing Dens Road Industrial Estate and this site are sharing the land property for industrial development purposes. The main area of the site subject to development covers a rectangular shape of approximately 140m x 100 m.

The site is substantially surrounded with existing tree shelter belt from south to the north at east face. There are two main connections going to the city. First is the Wardmill Road on the west side and another is the Andrew Welsh Way on the east side. The site is also neighbour to the housing developments which are located at the east and at the south site. These dwelling units consist of terrace housing and detached housing type, which indicates the adoption and acceptance of variety of architecture around the site.

The site from the north is covered with a long pathway which is diverted to two ways. Adjacent pathway at the west-north boundary of the site ends next to the bridge. At the east-south pathway is linked to the Andrew Welsh Way. Beyond the site environmental developments, the existing green area and the pedestrian pathway offer great walking and cycling opportunity for the occupants of this site. In addition, the existing trees and bushes will improve the site appearance and will keep the site separated from other lands in a natural way.

provided by Google Earth

provided by Google Earth

SITE DETAIL - LOCATION AND SITE PLAN

OWNERSHIP

The Angus Local Plan Review (adopted by Angus Council on 2009) including Policy SC9 is searching for the delivery of affordable housing. Accordance with the Policy SC9, the affordable housing should contribute against Arbroath 20% Low Cost Home Ownership (LCHO) Housing. (Angus Council Affordable Housing Policy Implementation Guide, 2009, p1) In this regard, the proposed sustainable and affordable housing development with 62 housing units in 1.48 ha area placement will meet the affordable housing requirement.

THE CURRENT POLICY AND STRATEGIES

Recent years, as the awareness and knowledge increases about carbon emission and its impacts, the policies, target strategies and action plans in this relation have become more important. The solution is substantially centred around achieving the sustainability in every area of life. Accordingly, buildings are the large part of the solution. The Scottish Building Regulations (2013, p359) recognize the Climate Change (Scotland) Act 2009 legislative agenda in order to eliminate the greenhouse gas (GHG) in Scotland. The initial target of the Act is reducing emission (compared to 1990) %42 by 2020. And, in the long term, %80 cut in emission is the target of Scotland by 2050. Addressing this major concern will require bold decisions. And one of the challenges is in the construction sector, which is the major contributor to the C02 emissions. (Scottish Building Regulations, 2013, p359) Buildings consume nearly %40 of global energy and cause %30 of global C02 emissions. (Clark, D.H., 2013, p16) Accordingly, the UK Government has set out a target for the new housing developments after 2016 must be zero carbon. (Dunster, B., Simmons, C. and Gilbert, B., 2008, pxv) In this regard, the way of energy generation and the efficient utilization of energy in buildings takes a primary role against achievement of set out targets. The building performance with increased energy efficiency methods as well as adoption of renewable energy solutions are the greatest fundamentals of Scotland’s approach to overcome climate change. (Scottish Building Regulations, 2013, p359) However, legislation is not only the driver towards energy and CO2 reduction in buildings, the fast advancement in Green Building Councils around the world and the environmental volunteer assessment methods such as BREEAM, LEED and Greenstar acknowledge the necessity of taking action. (Clark, D.H., 2013, p17)

In relation to the sustainability, not only energy factor, but also the major principles social, economic and environmental factors have to be considered. The ecological development: “water conservation, the protection or enhancement of site biodiversity, the use of low impact construction materials, facilities for recycling, provision for public transport, cycling and walking” and other facilities should be considered as practically possible. (Dunster, B., Simmons, C. and Gilbert, B., 2008, p5) As a result, such development in the Wardmill Estate land will propose a high code for sustainable homes and Average energy efficiency (SAP) rating. On the other hand it will “develop opportunities that continue the physical and economic regeneration of the town” set by the Angus Local Plan Review (2009, p110) as one of the issues facing Arbroath today.

Aims:

The main aims can be put forward for this proposed development:

A holistic and comprehensive approach for a sustainable community of houses that will be the benchmark for following similar developments around the site in relation to the zero carbon and passive house principles.
To meet the high quality house standards within the affordable housing typology scale.
Evaluation of the land potential energy due to renewable sources in particular solar and wind power, and adaptation these unlimited sources to the main heating system or electricity network.
To achieve high life standards as well as creating valuable social community, but also providing low energy cost and economical solutions to the homeowners within the boundary.

Objectives:

There are a number of principles and standards are evaluated through the exemplary Code 6 homes around the UK and Europe. The major principles behind these houses are illustrated in order to indicate the applied implementations and principles in this proposed sustainable housing development.

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Accordia Housing, Cambridge:

The huge diversity of people has been reached by the mix of community, providing houses, apartments and duplexes in a range of 1 bedroom up to 5 bedroom for mixed tenure. Accordia offers 30% affordable mixed-tenure equally divides between for rent and low cost housing for sale. With a focus on affordable housing and the variety of dwellings has been considered at the design stage of the proposed housing development. The diversity of dwellings has arranged mainly between 2 and 3 bedrooms. However, as an option from 1 to 4 bedroom dwelling will be offered. The compactness and density allowance will be lighter in the proposed area in accordance with the Accordia density is 54 dwellings per hectare(dph) whereas, the proposed area density is 42 dph. The dwelling density in proposed site will allow more free green spaces and individual comfort area for home owners compared to the Accordia. The significant methodology in creating public spaces, pedestrian routes and also environmental strategies has been considered as Accordia observed. The existing green belt consisting of old trees and bushes around the boundary especially at north side will be remained same. To keep the existing biodiversity, the existence of green area has primary importance.

In addition, the presence of natural green area will increase the environmental prosperity of the site. It will create a natural borderline among other housing developments. The similar dwelling typology is implied to the proposed site as in the Accordia. By this way, the major principles are adopted from Acordia such as buildings with gardens, small width of roads, cycling and walking pathways, community and garden spaces between dwellings. These economical approaches to the site will deliver social and environmental places. For example, the existing way at west site will be assessed as pathway and will lead directly to the green space which will create a green appearance rather than grey housing blocks. On the north side, the road width kept 6 meters from one face to another face of dwelling. Therefore, the house owners encourage not to park outside rather than a parking area similar to Acordia housing typology.

BedZED, London:

As Dunster, B., Simmons, C. and Gilbert, B. indicatedBedZed London was the UK’s largest mixed use, carbon-neutral, high-density development which sets new standards in sustainable building when constructed for the Peabody Trust in 2002.”The diversity of the energy supply with the purpose of generating energy from renewable sources at maximum level as the land offers but also the effective use of the supplied energy at minimum surplus. The system is run by biomass, combined heat and power (CHP) with the addition of photovoltaics (PV) and natural wind powered ventilation in this exemplary site. This pioneering development in London can be adapted at a smaller scale to the proposed site as practicably possible. For instance, a CHP unit on the site will provide the heat and electricity supply, but when the peak times occur during the year, the secondary heating management, such as district heating (DH) or additional boiler will be useful to deliver the required energy. (The system development will be discussed in the design solutions section.)

Another important principle in Bedzed housing development is about terraced homes design and orientation. This type of method will be applied to the proposed site. The terraced flats are in east-west orientation will maximize the solar gain throughout the year. The front façade of the terraced flats will be

placed with wide windows. The open area will be used as a sunspace. This part of the dwelling will perform as a “buffer” that will reduce the effect of temperature changes in an adequate level throughout the year.

The main dwelling parts, particularly roof, wall, window and floor elements are highly important mainly for thermal mass, energy conservation. The wall and ceiling thickness is taken 400 mm and floor thickness is designed as 300 mm in the proposed site as motivated from Bedzed housing development. The most part of this increased part filled with insulation that will reduce the transmittance and increase the U-value. By this way, the SAP required levels will be also highly satisfied.

"BedZED 2007" by Tom Chance from Peckham - flickr: BedZED. Licensed under CC BY 2.0 via Wikimedia Commons - https://commons.wikimedia.org/wiki/File:BedZED_2007.jpg#/media/File:BedZED_2007.jpg

Clay Fields, Suffolk:

The Clay Fields housing development was important to show the sustainable housing can be constructed in a reasonable budget. As a result, the product including only supply costed nearly £135 per m³. This development consists of 26 sustainable and affordable dwellings in Suffolk. As a sustainable feature implementations; green sedum roof, natural materials, rainwater harvesting, insulation and glazing, waste and recycling are applied. In addition, the application of lime renders to the gable ends in this development will be considered. While, the application is economical, it provides capturing carbon from the air, helps airtightness and resilience by using recyclable material.

The important parameter will be taken into account in relation to the biomass boiler and its utilization. The biofuel boiler with 150-180 kW output powered by wood pellets for 26 dwellings has been deployed in this area. It is understood that the biomass boiler with its delivered capacity saves a great amount of carbon emissions, in contrast it was too big for this scheme and economically not viable as expected. At this point, the optimum demand for energy in the

proposed area for around 60 dwellings should be taken into account rather than design method according to the maximum demand of energy of this area. Furthermore, however, the biomass boiler has become not economical, the cost of the district heating system in this housing development was around £230 000 and the proportion of £100 000 cost has been received as a grant from the Carbon Trust Accordingly, the incentives and tariffs should be followed properly, which will enable renewable energy technologies affordable in housing schemes since the issue of clean energy generation is a global concern.

The roof plan and design enable all housing units take advantage of the sun either as solar power in return electricity, especially in summer or solar gain in return natural heating in the house especially in winter. The design roof angle has been taken from one side angle 30 and another 60 in a proposed sustainable building which has a quite similar cross-section against Clay Fields housing development. (Figure 17)

Home Zone Terraced Housing, Canning, London:

The urban housing in Canning town costed £6.7 million comprises 55 mixed tenure units within a new shared space within the boundary of gross internal area 5250 m2. This development had a substantially limited area compared to the proposed site. But, the wide windows design and brick material use shows the identity of these dwellings. The planning inside of the apartments and the flats is quite conventional. Sergison Bates approach to the cul-de-sac culture in Canning Town, 2009)

Freiburg Vauban, Germany

The main objective of this scheme was to implement a city region in a “co-operative, participatory way which meets ecological, social, economical and cultural requirements.” The most distinctive side of the project is the contribution of the people who are developing the region. The main objectives of the project put forward in a comprehensive approach. They give the same importance to the quality and performance of the buildings as well as the community development within the boundary.

Before the scheme has been set out, the city council gave a time frame to the co-housing-groups to solve all the questions about the scheme. By this way, the share of involvement of groups to the scheme creates a belonging position towards to the project. For example, in this respect, the question about delivering the low energy standard for all houses and central co-generation plant has been solved by CHP with wood chips and design of passive houses and advanced energy methods. The CHP unit powered by %80 wood-chips and %20 natural gas connected to a district’s heating grid. And thermal solar collectors in some buildings help to the energy supply. Through efficient energy supply and insulation methods , %80 CO2 reduction has been achieved in this scheme.

DESIGN PRINCIPLES AND DESIGN GUIDES

The number of key design figures were made in order to meet the housing associations' target strategies towards zero carbon house developments for the next centuries:

1) In order to reduce heat loss, achieve the maximum level of energy efficiency, a fabric first approach was adopted with an airtight highly insulated building envelope.

2) The housing type designed in typical terraces in order to decrease the amount of external walls exposion to outdoor heat variations.

3) The majority of houses was orientated towards south in order to catch as much free energy from the sun as possible

4) Roof were tilted at angle of 30 in order to further installation of PV or solar thermal systems that will be operated at optimum level.

5) All car parking was designed off street, under cover in mews type applications, creating a streetscape in which the pedestrian has priority.

6) Private external space was provided in all dwellings.

7) A large shared community space was provided at the centre of the development

8) The narrow frontage of the homes allows for standardised building components reducing cost.

9) Space has been aside for the installation of a community based heat and power distribution system. (i.e. CHP)

DESIGN SOLUTIONS - RENEWABLE ENERGY

Achievement of the target strategies, policies and action plans in relation to the carbon emissions and energy efficiency, without inclusion of utilization of renewable energy technologies to this agenda, it will hardly become a reality.

Renewable energy can be utilized in two forms of energy in buildings: Heat and Electricity. The systems with current technology can be evaluated as follows:

NOTE: Thanks for this figure preparation to my classmate Donald Minty for his contribution and consent on this site.

Heating and Electrical systems:

In general, the control or transfer energy in heat form is substantially difficult process. The change in demand from winter to summer during the year also reduces the most of the heating system efficiency. In contrast, in electrical systems, any excess generation of electricity through renewable energy technologies can be exported to the national grid. In other words, there will be no surplus energy in the electricity system at a housing development scale. As a result of fact, the precise calculation of demand of heat of a particular land during the year requires a great attention for achievement of the energy efficiency, however it changes from one period of time to another.

Solar thermal and Photovoltaics:

Fuel Used: -
Main Components:

Solar thermal: Solar panels (flat panels or evacuated tube) and thermal storage tank
Photovoltaics: PV panels, inverter

Potential Barriers:

Solar thermal: Available roof area, decentralized domestic hot water(DHW)
Photovoltaics: Available roof area, overshadowing of panels (Clark, D.H., 2013, p139)

Energy Production:

The solar energy calculation is relatively easy. The irradiation of sun in a particular place depends on the location, the orientation and the tilt of the roof. (Clark, D.H., 2013, p140) The efficiency of solar energy is related to the panel feasibility, overshadowing periods and system losses.

Mean solar irradiation on directly south facing panel at Dundee (closest data to the Arbroath) in a year:

The numbers indicate the kWh/m2/day onto a horizontal surface.

The average per year, according to the table: 2.40 kWh/m2/day * 365 days = 876 kWh/m2

The assumed efficiency and losses = %50 (as an example – it varies)

The annual energy = 876 * (1-0.5) = 438 kWh/m2

The annual energy per household (The available roof area (can be given as minimum 10 m2 per house type) = 438*10 = 4380 kWh

The average household energy use in the UK in electricity form = 4648 kWh (Wilson, L., n.d., Average household electricity use around the world)

If the above conditions are provided, the total consumption of electricity and the production of energy from the sun can be nearly balanced throughout the year.

Availability:

In general, the utilization of energy from PV panels rather than solar panels appears to offer more advantages. First of all, the electricity production can be more useful at home than heat generation. Because, the primary heat demand will be supplied by the CHP system to the houses. Secondly, if there will be surplus energy production throughout the year, this extra energy can be transferred to the national grid and in return can be paid because of this excess energy production. In addition, the solar power in proposed area can be used more effectively through electricity production rather than heat production. Accordingly, the detail calculation will be made by SAP2009.

Heat Pumps:

Fuel Used: Electricity
Main Components:

Air source heat pumps (ASHP): package unit
Ground source heat pumps (GSHP): unit+pipes in ground (boreholes or trenches)

Potential Barriers:

Low water temperature
Electricity supply capacity
For GSHP land availability (Clark, D.H., 2013, p146)

Energy Production:

Heat pumps produce heat energy through consumption electricity. They are designed for the movement of heat flow in the opposite direction of inherent heat flow by captivating heat from a warmer place and release to a cold place or opposite way regarding to the condition. (Wikipedia, 2014, Heat Pump) The system is more useful where there is no available biomass for wood pellet burners or where cooling is required in the summer. (Dunster, B., Simmons, C. and Gilbert, B., 2008, p196) From this point of view, as the CHP provides the primary energy, including the houses in passive house standards will substantially meet the required features towards heat pumps offer.

Biomass boiler:

Fuel Used: Wood chips or pellets
Main Components: Boiler, thermal buffer tank, biomass store, ash bins
Potential Barriers: Air quality (flue emissions)
Space requirements for fuel storage and delivery truck movements
Reliability and affordability of fuel supply
Maintenance cost (Clark, D.H., 2013, p142)

Energy Production: An alternative way of production of heat is biomass boiler which is powered by mainly wood chips or pellets. But for providing community heating main for a group of houses and apartments, CHP systems will be more energy efficient solution. (Dunster, B., Simmons, C. and Gilbert, B., 2008, p197)

Wind Turbines:

Fuel Used: -
Main Components: Wind turbine and inverter
Potential Barriers:

- Noise

- Vibration

- Visual impact

- Lack of wind Planning permission (Clark, D.H., 2013, p160)

Energy Production:

The energy generation simply depends on the wind power on the site. The kinetic energy of the wind is transferred to the form of electricity energy through wind turbine inverters.

However, the north site has surrounded by trees and bushes, as the southeastern site is more open area that is exposed to strongest wind compared to the other directions according to the Weather tool software. (The data taken from Dundee region)

There is a practical calculation for feasibility purposes to estimate approximate wind potential in a particular area.

Capacity factor(%) =

Turbine capacity (kW) * 365 days*24 hours

From this calculation;

Annual electricity (kWh/annum) = turbine capacity (kWe) (electrical power) * capacity factor * 24*365 hour

For a 10 kWe wind turbine on an urban centre building in the UK, supposing capacity factor of %5, the building generates 4380 kWh/annum.(10 Kw * %5 * 8760 hours )If the turbine was installed to the windy Scotland hills, the capacity factor can be taken as %30. However, the installation of big turbines at a high level on top of buildings will be required to generate adequate energy which may not be an affordable solution.

Combined Heat and Power (CHP):

Fuel Used: Gas or biofuel
Main Components:

Gas CHP: engine and generator
Biofuel CHP: engine, generator and fuel tank
Trigeneration: CHP plus absorption chiller

Potential Barriers:

Limited operating hours (<4500/year)
Low annual heat to power energy consumption ratio
High peak heat to base heat energy demand
Grid infrastructure (Clark, D.H., 2013, p167)

Energy Production:

Production of heat and electricity energy through combustion of biomass, natural gas, biogas or several wastes. In other words, these systems are basically boilers, which deliver hot water and heating at the same time generate electricity as a by-product. Addressing to the minimum CO2 emissions objectives, running CHP systems with biomass materials are more effective. However, the size of the CHP is highly related to the source of combustion. For this reason, wood pellets can be a great decision to run CHP. Firstly, it provides a clean source of energy. Secondly, compared to the other sort of biomass materials such as wood chips, wood pellets have the same energy content in 3.5 times less volume. It will presumably affect the size of storage space. Another is that, wood pellets produce “less ash and particulate emissions” after it burns. However , the cost of the material and the delivery truck periods should be arranged for the long term use. The location of the CHP system as positioned at design scheme should be close to the road for easy deliveries of wood pellets.

Regarding to some research and scheme, “district heating with combined heat and power (CHPDH) is the cheapest method of cutting carbon emissions, and has one of the lowest carbon footprints of all fossil generation plants” In Glasgow, the Wyndford Estate is a great example that save over 7000 tonnes of carbon emissions per year as well as cost effective. In general, CHP systems provide constant heat or electrical demand. But, for the certain “peak period(cold winter days) and periods of very low demand (summer)”, the required energy can be delivered through back-up boilers.

Mechanical Heat Recovery Unit (MVHR):

MVHR will be installed either near to the floor, ceiling or outside door of the house. It will supply fresh air to the rooms and extracts exhaust air from the bathroom and kitchen. But the workability of MVHR is highly related to the airtightness of dwelling. And, a number of features should be considered. For instance, the most energy efficient fans and heat ex-changers should be installed. Minimizing the duct length to decrease hydraulic pressure and maximizing the solar gain will provide sufficient electricity to empower MVHR especially in the summer. The efficiency and energy consumption of MVHR is considerably related: a) the air change frequency inside the house, b) its proper maintenance essentially changing the filters c) control management: when the owner of house goes to vacation for a period of time, the fan speed can be adjusted as a minimum, whereas during the high occupancy of the house, the fan can be can be increased.

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