4381504029075Science and Materialsaurh443 – HNC building studies
J. Armon Williams – Grwp Llandrillo Menai
790000Science and Materialsaurh443 – HNC building studies
J. Armon Williams – Grwp Llandrillo Menai
In this assignment I will be researching a case study with regards to the impact and application of the science of materials associated with the structure. I will be explaining the background of the design and how the materials contributed to the structures performance and issues related to those materials.
In the second task in this assignment I will be using information from various sources to calculate the total heat loss and total heat gains of a council chamber built in the late 1800’s.
Built for the wealthy Pennant family on the profits of Welsh slate and Jamaican sugar, Penrhyn Castle is an extravagant example of early 19th century neo-Norman architecture.
The present house was designed by Thomas Hopper in the form of a Norman castle and was constructed for George Hay Dawkins-Pennant between 1820 and 1837.
The castle was purely designed the way it was to impress royalty and the guests of the Pennant family who came to visit. With the inside of the castle designed as a maze for people to get lost in.
Penrhyn Castle is a Grade I listed building and is listed as one of the most important large country houses in Wales and regarded as the masterpiece of its architect.
In 1949, after the death of the fourth Lord Penrhyn, the land and title was separated and then in 1951 Penrhyn Castle came under the care of the National Trust.
http://orapweb.rcahms.gov.uk/coflein/D/DI2008_0359.jpgThe whole castle is constructed of local rubblestone with internal brick lining, but all elevations are faced in tooled Anglesey limestone. The limestone was quarried at Moelfre on Anglesey and closely resembles Penmon limestone which was used extensively across Britain. Two notable examples of Penmon limestone are the Bridges over the Menai Straights. This stone was chosen to face the castle for its grey carboniferous colour that is slightly darker than normal limestone.
Limestone is a very compact sedimentary rock that is usually formed at the bottom of lakes and oceans and is made from the remains of sea creatures and shells and formed under the sea millions of years ago.
Limestone is used in the construction industry due to its strong and hard properties. It is also used as a building material because of its availability in the world roughly representing 10 percent of all the sedimentary rock in the world. Although limestone is a hard and strong material it is still very easy to work with and carve. Special care needs to be taken when cleaning limestone because of its sensitivity and susceptibility to acid. This weakness can be seen in the breaking down of some ancient structures built with limestone due to acid rain.
The stones are held together with ashlar lime mortar. It is a fine-grained lime mortar for building and pointing tight joints in brick or stone. Ashlar mortar is perfect for laying bricks and cut stone on a tight bed of thin mortar. It is made using natural hydraulic lime, sand and stone dusts. It has excellent water retention and does not rapidly dry when trying to position the stones. This mortar is generally suitable for joints of between 3 and 6mm thick.
The castle has 70 different roof structures that cover a total area of 4000m².
https://media-cdn.tripadvisor.com/media/photo-s/08/fc/f4/ba/penrhyn-castle.jpgCovering the 4000m² of roof area is a mixture of lead and Penrhyn slate from the local quarries. The flat lead roofs are concealed by castellated parapets.
Slate is a naturally-occurring metamorphic rock. It is derived from shale or mudstone that has experienced intense heat or pressure beneath the earth’s surface. Slate is made up of parallel foliated plates. This gives it the ability to break smoothly and evenly along its cleavage and is valued for its ability to break into thin plates.
The lead has been used as a roof covering for its high density and resistance to corrosion. It is also very malleable and can easily be beaten to shape without breaking.
Originally there wouldn’t have been any water-resistant barrier underneath the slates. But since the National Trust have taken care of the castle nearly all of the slate roofs have been stripped and reroofed with Penrhyn slate to match the original. After a bat survey was carried out and bats were found in the area breathable membrane was not allowed to be used. Breathable membrane would allow air to pass through the membrane to circulate in the loft space but would not let any water vapour through. Because of the bats type 1F felt was required to be used. Type 1F is a non-breathable membrane that is suitable for cold ventilated roofs to safeguard against wind driven rain, snow and dust.
Beneath the roof coverings are the timberwork holding them up. The pitched roofs sit on wall plates that are bedded in the lime mortar onto the internal skin of brick work. The flat roofs slot into sections of the walls where brickwork has been left out. The timber for all the roof structures had been sourced locally from land owned by the Penrhyn estate.
Beneath the roof structure are the complex curved timber suspended ceilings.
https://media-cdn.tripadvisor.com/media/photo-s/08/fc/f3/a8/penrhyn-castle.jpghttp://media-cdn.tripadvisor.com/media/photo-s/08/5b/a6/f4/penrhyn-castle.jpgMany the carvings for the ceilings and the columns have been carved out of timber and then painted to look like stonework.
In the part of the house that were occupied mostly by the servants the sash windows were completely made from pitch pine.
Pitch Pine is orange to reddish-brown in colour and very resinous. The growth rings are clearly marked by the contrast between the light earlywood and darker, more dense latewood. Pitch Pine has identical strength properties to Douglas Fir. It also dries well with little degrade and only small amount of movement when used.
In the main parts of the house the sash windows are constructed differently. The sections of the sashes and the boxes that were facing the inside of the property were made from oak while the parts facing the outside were pitch pine. It’s not sure why this technique was used. With the Pennant family spending an estimated £150,000, that would have a current equivalent of about £49.5m. This technique would not have been used to save money as so much was spent in making the place perfect plus all the timber came from the family’s local forestry’s. All the internal timber work has been given a paint wood graining effect so it all looks the same.
Oak is the most commonly used hardwood with white oak being more durable than red oak. However, oak dries slowly, tends to split and warp and has a high shrinkage rate.
The many doors in the castle are also made from pitch pine and are hung using brass ironmongery. Brass is a metallic alloy made of copper and zinc. The malleability, good resistance to corrosion and how easy it was to work with have made it the usual metal of choice for decorative ironmongery.
The large external doors that are found in the old stable block that is now the train museum are again made from pitch pine. These are hung with large decorative steel hinges that are fixed to the face of the doors. Properties of the steel would be its great formability, durability and strength. As well as the steel hinges there are numerous steel studs that have been hammered into the doors about 150mm apart as decorative features. The rain water that runs down the face of the door then sits on these studs and run into the door rotting them from the inside.
Many of these doors have been pulled down in order to carry out repair work. The old rotten timber has been cut away and with the consent of listed planning consent pieces of Sapele has been spliced in place. The Sapele is a much harder wearing timber than the pitch pine and is frequently used in the construction of external doors and windows as a substitute to mahogany. The hardness and medium density makes Sapele wood very stable and predictable.
Originally the castle had 80 fire places that were constantly kept going by the many servants that worked for the family. These were later replaced when the National Trust took care of Penrhyn castle by 4 oil burning boilers. These were used to heat up and supply hot water to the castle, offices and flats for the staff that worked at the castle. In 2016 the National Trust started work on building a new boiler house and woodchip storage facility in preparation of replacing the old oil fuelled system with a new biomass renewable heating system to heat the castle. The boiler now uses locally sourced woodchip and woodchip harvested from their own woodlands in the area, to heat the castle. The wood pellet fuel supply is sustainable, and biomass boilers are carbon neutral will not produce carbon dioxide emissions to harm the environment.
right610https://fftf.org.uk/wp-content/uploads/2016/07/harvest-to-heat.jpgThis was part of a large project to make the castle greener that had already seen the installation of half an acre of solar panels that generates 25% of the electricity used at the castle. This electricity helps power the thousands of LED light bulbs that have been used to replace the old incandescent light bulbs that are more expensive to run.
7000m2 of loft insulation has also been put in the loft space in previous years in an attempt to insulate the castle and reduce the running cost for heating.
Currently the National Trust staff at Penrhyn Castle are working with scientists from Bangor University and Trinity College Dublin to find a way of heating the water coming into the castle by waste-water heat capture technology. This technology that is being invented would transfer the heat generated from the waste water running through the wastepipes to heat the water entering the castle.
The whole castle sits on top of a vaulted basement. The brickwork arches transfer the weight of the castle to the solid stone beneath. During a survey of the castle done last year it shown that the brickwork has not moved at all since the castle was finished in 1837. The basement is also home to the miles of pipes and cables that supply the building with its services.
4 x 50 = 200m²
4 x 30 = 120m²
4 x 30 = 120 ÷ 2 = 60m²
200 + 120 + 60 = 380 x 2 = 760m² total wall area.
5 x 3 = 15 x 4 = 60m² total window area.
a² + b² = c²
4² + 15² = c²
16 + 225 = c²
241 = c²
15.524 = c
15.524 x 50 = 776.2 x 2 = 1552.4m² total roof area.
30 x 50 = 1500m² total floor area.
The CIBSE guide A Section 1.3 gives details of recommendations on suitable temperature ranges in rooms. Conference/boardrooms and open plan offices temperature recommends between 21?c and 23?c. If 22?c is chosen for an internal temperature and assume a low of 5?c outside that would give me a temperature difference of 17?c
“The mean annual ground surface temperature should be close to the mean annual air temperature although often shows a variation of ± 1 °C.”
Random rubble wall conductivity – 1.5 w/mk (homebuilding.co.uk)
Protected lime mortar – 0.88 w/mk (lecturer handout)
Exposed lime mortar – 0.94 w/mk (lecturer handout)
This is assuming that the conductivity of mortar and lime mortar are the same.
Wall u-value – 0.912 w/m²k
TR = 0.123 + (0.020 ÷ 0.94) + (0.6 ÷ 1.5) + (0.020 ÷ 0.88) + 0.53
= 0.123 + 0.021 + 0.4 + 0.023 + 0.53
u-value = 1 ÷ TR
= 1 ÷ 1.097
= 0.912 w/m²k
Single glazed sash window u-value – 5.0 w/m²k (cibsejournal.com)
Roof u-value – 1.5 w/m²k
Floor u-value – 2.4 w/m²k
Total fabric heat loss of wall = 0.912 x 700 x 17
= 10852.8 w
Total fabric heat loss of window = 5.0 x 60 x 17
= 5100 w
Total fabric heat loss of roof = 1.5 x 1552.4 x 17
= 39586.2 w
Total fabric heat loss of floor = 2.4 x 1500 x 17
= 61200 w
Total fabric heat loss = 10852.8 + 5100 + 39586.2 + 61200
= 116739 w
The recommended ventilation air change rate for assembly halls are 4-6 per hour. Assuming the same air change rate for the council chamber building and taking the average of 5 per hour.
4 x 30 x 50 = 6000 m³
4 x 30 x 50 = 6000 ÷ 2 = 3000 m³
6000 + 3000 = 9000 m³ total volume of council chamber.
QV – heat loss due to ventilation
V – volume of air (m³)
N – Recommended air change rate (p/hr)
?t – Temp difference ?c (int/ext)
QV = 0.33 x V x N x ?t
= 0.33 x 9000 x 5 x 17
= 252450 w
252450 w heat loss due to ventilation.
252450 + 116739 = 369189 w
369189 w total heat loss
It is envisaged that there will be a total of 120 people in the chamber building during meetings. Assuming they are all adults, and will all be seated each person will be producing 120 w of heat (wiley.com).
Assuming that the council chamber has traditional fluorescent strip lighting that are giving off 400lux these lights will be producing 20w/m² floor area (wiley.com).
120 x 120 = 14400 w
20 x 1500 = 30000 w
14400 + 30000 = 44400 w
44400 w total heat gains
In this assignment I researched a case study with regards to the impact and application of the science of materials associated with the building. The building I chose to research was Penrhyn Castle. Using information found online and information I have learnt from years of carrying out work at the castle for the National Trust I was able to write this assignment.
I researched why the castle was designed the way it was and the materials that have been used in the construction of the castle along with the properties of these materials.
Looked into the way the National Trust are attempting to make the castle much greener and carbon neutral by installing half an acre of solar panels and removing the four old oil boilers and replacing with one biomass boiler in their place. Also mentioning the new innovative ideas, they are working on for heating the water entering the castle.
In the second task of this assignment I used information from various sources such as lecturer handouts and information found online to find the u-value of the materials used in the construction on the council chamber and then calculated the total heat loss and the total heat gains of the chamber from the heat generated by the lights and the people in the building.