Reducing the Development Cost of High-Density High-Rise by 10 - 20%

The key inventive step in the Honeycomb apartment concept is the elimination of corridors and replacing them instead with of sky-courts. Re-inventing how residents are connected from the public street to their individual apartments overcomes the social problems that have been linked to the nature of corridors and “intermediate space” but also opens up to various ways of reducing costs.

The chart below that breaks down the selling price of a typical apartment helps us better understand by how much the checkerboard can help make housing affordable.

Here the components that make up the price of a typical apartment is listed with the bigger costs at the bottom. In this example, the biggest cost factor is land followed by the cost of architectural works, profit, car park, M&E services, superstructure, infrastructure, consultant’s fees, bridging loan, substructure, preliminaries, marketing costs and contributions.

The key thing about the Honeycomb checkerboard-plan is that it simultaneously attacks these multiple cost-centres:

•  Most significantly, higher densities also allow the cost of land for each unit to be substantially reduced: more units share the cost of the land.
• By radically reducing corridors and improving the plan efficiency, the gross floor area is reduced, and the cost of architectural works is reduced in the same way.
• By reducing the gross area and the number of floors needed to support the set number of car parks, the cost of building them is substantially reduced.
• With fewer lifts, their costs and the costs of gen-sets and electrical supply supporting them go down. Lower fire-risk of shorter buildings also bring down the M&E costs.
• The lower GFA and smaller columns needed to support a shorter building reduce the structural cost.
•  More units share the cost of infrastructure that is based on land size.
• The interest payable for the bridging loan is lower when the building is finished faster.
• The substructure cost is reduced proportionately to the reduction in GFA
• The preliminaries lower due to lower cranage and if the building is finished faster.
•  Marketing costs is lower when the apartment has desirable features found in more expensive products.
•  More units share the cost of contributions that is based on land size.

From this list, all but two of the cost-centres mentioned above have been affected. But these two factors – profit and consultant fees – are calculated based on a percentage of development cost and when this has been substantially reduced, so can the amount of profit and fees for consultants. So, in both direct and indirect ways, we have shown that ALL the cost-centres have been tackled by the checkerboard design.

This validates the strategy that we have adopted. To really reduce the cost of homes to make them affordable, re-looking at the apartment typology and re-designing it from first principles offers a way forward.

10 to 20% SAVINGS

All these cost-savings point to checkerboard-plan apartments to be even cheaper to build than conventional high-rise.

A preliminary estimate of all the savings discussed above indicates that it is possible for affordable housing below RM300 per square foot to be provided in the major city centres where the price of land is within RM300 per square foot and where the density permitted is 130 units an acre and the parking standard is 2.2 car park per unit.

A COMPARATIVE STUDY

A study has been done to compare an actual project with a hypothetical Honeycomb alternative on the same site. We were able to enlist the help of the Quantity Surveyor of a real project near Putrajaya by PR1MA, a government-owned company tasked with delivering 500,000 affordable homes by 2020. At the time of writing, the project was at piling stage. 

Against this existing project based on a conventional design, a Honeycomb alternative was designed and it was costed by the Quantity Surveyor using information provided by Arkitek M Ghazali and its Structural and M&E engineers.

The initial result shows that the potential savings are as substantial as we expected. The following table presents a summary.

Instead of two 15-storey blocks with a separate 6-storey car park block, we just had five 8 storey blocks on the car parking all on the ground floor. Naturally, there was a reduction in the construction cost per square foot of gross built-up area (GFA):  just over 9% from RM119 to RM109.

The average Net Saleable Area for each unit of only 88.11sm is increased by 21% to 106.75sm, but allied with a slight reduction in Gross Development Area: the efficiency of the layout, i.e. The Net Saleable Area as a percentage of the Gross Development Area has greatly increased from 49% to 60%. This means that there is a huge reduction in the construction cost per square foot of Net Sellable area of just over 24.8% from RM242 to RM182!

In this example, the Honeycomb alternative had a slightly lower density, 62 units per acre instead of 70. But with bigger units the Net Plot Ratio slightly increases from 1.52 to 1.56, causing a slight reduction in land cost per square foot of saleable area. With the land priced at only RM80 per square foot, the effect is not large.

However, with important land component of development costs virtually unchanged, the large reduction in construction cost has a more moderate effect on Selling Price: the alternative design can be sold at the average price of RM273 per square foot instead of RM323, a reduction of about 15%.

Table 2 A COMPARATIVE STUDY

SITE INFO	EXISTINGPR1MA PROJECT	HONEYCOMB ALTERNATIVE
Site	Real site with irregular boundaries	The exact same site
Description	Two 15-storey apartment block and a separate 6-storey car park block with amenities and facilities.	Five 9-storey linked honeycomb blocks apartments with facilities and entrance on the 1st floor of one block and car parks all on the ground floor.
Size	6.72 acres at RM80 psf	6.72 acres at RM80 psf
KEY COST MEASURES
Gross Floor Area/ Units (m2)	179.48	177.95
Net Sellable Area /Unit (m2)	88.11	106.75
Efficiency	49%	60%
Apartment Block Height	15 storeys	8 storeys
Car Park Floors	6 floors (separate)	1 floor
No of Lift stops	15 stops	4 stops
Density	70 unit/acre	62 unit/acre
Net Plot Ratio	1.52	1.56
Cost/GFA (RM)	119	109
Cost/NSA	242	182
Selling Price/NSA	323	273
PRICE REDUCTION		15%

This is well in the middle of our estimate for the cost savings achievable by the Honeycomb Apartment layout compared with conventional design. In this example, cost savings from construction was maximized and potential cost savings from land was not exploited because the land price was relatively cheap.

At RM80 per square foot, the potential savings from land did not merit the added cost of adding more residential floors and digging in a half basement car park. However, in cases where land is more expensive, the calculation would yield a different result.

CONCLUSION

Architects are not well known for helping to cut the cost of construction: it is said that every line an architect draws add cost.  If so, it’s better that we not draw anything at all, just let the engineers or builders do it.

I write this only half-jokingly because it is a very common perception and, after these 20 chapters, I hope to have shown it to be wrong.

When I was one of several architects doing low-cost mass housing work for in the late 90’s, the client had in mind that we adopt a standard design and the design responsibility of each architect was to do the make -up work on the façade to give some sort of identity to each project.

The hope at that time was that the standardized design of housing units would allow Industrial Building Systems of constructions to be adopted, taking advantage of the large numbers of repetitive elements to be manufactured and assembled.

Speeding up construction time, minimizing wet trades on site, taking advantage of economies of scale, manufacturing techniques and reducing labour, especially the need for skilled labour, all these can surely help reduce the cost of building homes. But we must take a realistic perspective.

The cost of constructing a house is an important cost centre but it’s not the only one. There is the land to acquire, infrastructural services to provide and many other development costs to bear.  Even just looking at construction costs, IBS mainly affects the cost of structural and wall elements, which in conventional construction only makes up about half of the building cost.

If structure and walls make up only half of the building cost and building cost contribute to only, say, 50% of the selling price of a home, then an IBS method of construction that involves only structure and wall directly attacks only a 24% component of the cost of construction, equivalent to roughly 12% of the price that a buyer pays for the home. So, if an IBS system saves 10% off the cost of structure and walls, this can only deliver a 1.2% reduction in price. From my experience, it is unrealistic to expect savings of more than a few percent of the total construction cost.

So, whilst better methods of construction should be pursued, we also must look for ways to reduce the cost of infrastructure, land and other costs.

A CASE FOR MORE RESEARCH INTO NEW TYPOLOGIES

This is where design can help. Not just another iteration of existing apartment typologies, but a more fundamental re-examination of how homes have been designed.  This is the basis of our research into new typologies.

In our Honeycomb Townhouse concept, compared to terrace houses, there is at least 50% more units on each acre of land and construction cost is also lower due to the sharing of roof, suspended floor and foundation between the upstairs and downstairs unit.

Compared to conventional terrace townhouses, both the upper and lower-level units have gardens, two car parks and ample window openings for all the rooms. We have shown at our project in Alor Gajah that if priced about 20% lower than a terrace house with the same floor area, people will buy them.

We have discovered through experience that five-storey walk-up flat is the cheapest housing typology in Malaysia. However, the two highest floors were hard to sell even when sold at the heavily subsidized prices.

The V-shaped Honeycomb Medium-Rise concept provides a very inexpensive lift that only shuttles between the ground floor and 3^rd floor to serve all units, a communal courtyard for all, and private front-yards for some units, at an attractive block layout that achieves a density that is about four times that of terrace houses.

It is envisaged that if the typical apartment is priced about 20% lower than a terrace townhouse and 40% lower than a terrace house, people will buy them. This new concept might be suited at the edge of small towns.

In the suburbs of major urban centres where developers must provide low-cost housing, we have come up with the Kotapuri concept where the low-cost and low medium cost housing, priced between RM42,000 to RM100,000 are placed on top of shops. Although sold at a loss, the marginal cost of building each unit of low-medium cost unit is lower than its price; the marginal cost of building each unit of heavily subsidized low-cost unit is not too much higher than its price. In this case, the shops pay for the land and much of the infrastructure cost. In locations where there is no demand for offices above shops, it is better to use the space above it to provide housing units that liven up the area and provide housing for the people who tend the shops.

Designed and managed properly the commercial and residential components can add value to one another. In this way, the subsidized houses are located near amenities and public transport rather than shunted to the furthest, least attractive corner of a development.

In the Honeycomb apartment concept, the key inventive step is the elimination of corridors and replacing them instead with of sky-courts. Re-inventing how residents are connected from the public street to their individual apartments overcomes the social problems that have been linked to the nature of corridors and “intermediate space” but also opens up to various ways of reducing costs, making it possible to reduce pricing by up to 20%.

At the same time, we offer products that are more desirable, that can overcome the major social defects of high-density high-rise housing.

In the last few years, private and public developers have concentrated either on landed property that are expensive due to the escalating cost of land or else on high-density high-rise block that are very expensive to construct. These new low and medium-rise Honeycomb designs provide a wider range of alternatives that can serve an important gap in the housing market between terrace houses and high-rise apartments that most Malaysians cannot afford, and the subsidized low-cost and affordable housing that either lose money or provide thin margins.

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Overcoming the Problem of Car Parks for High-Density High-Rise

THE PROBLEM OF CAR PARKS FOR HIGH RISE
Malaysia is reputed to have one of the highest levels of car ownership in the world. The planning requirement for apartments is two units of car parks for each unit, plus another 10% for visitors. This is a very high requirement compared to most other countries and has the effect of making our high-rise housing expensive.

MEETING HIGH CAR-PARKING REQUIREMENTS WITH THE CHECKERBOARD PLAN

As we design taller buildings to achieve higher densities, just adding on parks on the ground is not the way to do it. The additional area required to cater for the additional car parks increase the development land required: since density is units/land area, increasing the numerator is pointless if at the same time, we increase the denominator.

To achieve higher densities, multi-level car parks are necessary. They can be placed in an adjacent block or below the tower. Constructing an adjacent block is cheaper but at the cost of being requiring an additional area, hence resulting in a lower density. But whichever of the two, the effect on the distribution of built-up area is that a large built-up area is now dedicated for cars: the net sellable area becomes a smaller proportion of the total built-up area. Car parks takes up a lot of space. Each car needs an 8’ x 16’ space that works out to 128sf. The driveway takes up 20’. All in all, with ramps and having to consider building columns and staircases, the gross built-up area required for one car park is about 260sf: in fact, actual car parks make up less than half of the total area of a multilevel car park block. Two car parks for each apartment plus another 10% for visitors takes up 572sf of car park built-up area. This is more than half the size of a typical affordable apartment.

Net sellable floor area expressed as a percentage of total built-up area for high-rise, including the multi-level car park plummets is often less than 55%. The fact is, the car parking requirement for high-rise high-density housing has become a very heavy burden on the cost of construction.
Again, PR1MA is aware of this problem and have produced their own guidelines which try to address this problem. In their table, A1, the car park provision for rural areas is set at 2.2, suburban and urban areas at 1.65 and 1.1 in cities. Although this standard may face resistance from local authorities and householders used to the convenience of having two cars, in the longer term, promoting a less car-dependant life style makes sense.

Already, the average size of households in Malaysia has peaked , bringing down the average number of cars per household. With the expansion of public transport in Kuala Lumpur and the Klang Valley, plus the explosive growth in share-riding services like Uber and Grab, owning a car is not essential for young working people, as it once was. I believe that PR1MA can do a good job in convincing local authorities home-buyers to buy into the concept of the compact city that promotes high residential density, mixed use and is oriented towards pedestrians rather than cars.

The efficiency of car parks can be operationally improved by doing away with parking spaces that are strictly allotted. As currently practiced, car parking spaces are allotted as accessory parcels to each owner. However, this ends up with a lot of car parks being empty for long periods. A pooled system, as found in commercial buildings, can cut this slack, providing more car parking opportunities with fewer actual slots.

In fact, PR1MA’s guidelines presumes only two basic options – a stand-alone multi-level car park or a podium car park that sits below the building block.

Figure 15 Multi-level Podium Car Park

The latter is of course more efficient than the former. But the podium is still a poor choice. The podium takes up space larger than footprint of the tower or slab block above it. This increases the land area that is needed.  The car park podium also must be set back from the boundary by about 50’ from the front and 25’ from the side. Having to do so results in having fewer cars than car parks on the ground floor which are subject to much lower setback lines.

Is there a better solution?

DEEP PLANS: PROVIDING CAR PARKS MORE EFFICIENTLY

The checkerboard-plan was conceived to be car park design-friendly with columns spaced in an 8m grid. A car park circulation system also fits neatly into the 5-layered grid with two roads inside the building footprint feeding car parks on both sides.

Figure 16 Columns in 8.1m grid

There is a road that circles the outside of the building: it too feeds car parks on both sides. The ground floor plan is shown below.

Figure 17 Ground Floor Car Park Plan

On just one floor the design is already very efficiently with up to a density 136 units per acre and this one floor is good enough to support a residential density of 60 units per acre when the car park requirement is 2.2 car parks per apartment, 90 units per acre when the car park requirement is 1.65 car parks per apartment unit, and 120 units per acre when the car park requirement is 2.2 car parking spaces per apartment.

But can we provide for even higher densities? Is there an alternative to the conventional multi-level podium car park?

Our answer is to replicate the ground floor car parking layout in a basement floor. In fact, basement car parks are generally not considered at all for residential development because they are thought to be costly to build, needing temporary shoring and permanent waterproofed retaining walls, and costly to maintain, with a mechanical system to draw in fresh air and expel fumes as well as a smoke-spill system in case of fire.

Yet, a single basement level 7’ or more away from the boundary does not need temporary shoring or an expensive water-proofed retaining wall. An 8’ rubble retaining wall at the boundary plus a low 1’ concrete one on the car park building line will suffice, creating an air-well that provides natural ventilation, daylighting, a green planting strip and setback distance to meet current planning requirements.

Figure 18 Perimeter Retaining Wall and Air-well
It is also easy to design an access to a single basement floor, doing away with having too many ramps as shown in the plan below.

Figure 19 Basement Car Park Plan


As shown in the basement car park plan above, just two car park levels can already support a building above it that contains 133 units per acre when the standard is 2.2 car parks per acre, 170 units per acre when the standard is 1.65 car parks per acre, and 275 units per acre when the standard is 1.1 car parks per acre.

The options available are displayed in the drawings below.

A design strategy that achieves high-density with shorter buildings and which either eliminates the car-park podium or else substitutes it with a low-cost single basement floor will surely reduce construction cost and time. Combining it with a lower car parking standard and as well as a loosening of the cap on density will further multiply the savings.

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Tall Buildings Cost More than Shorter Ones; How to Maximize Site Coverage

Even if authorities allow higher densities, high-rise would still be expensive. Taller buildings cost more to build compared to lower ones. As we go higher, there are thresholds above which costs become disproportionately more onerous.

Structures cost more the higher we go, as the columns on the lower floors need to be stronger and as lateral forces become more critical.

Below five storeys, lifts are not considered to be necessary, but at five storeys or above, we must provide them. As we go higher, more lifts are required, not only increasing the cost of installing and maintaining them, but also taking up more space, and thus reducing net sellable area. Lifts above 20, 30 and 50 stories also get disproportionately expensive as they need to move faster and must carry longer and heavier cable ropes.

With respect to fire-safety, above seven stories (top most floor 18.3m above fire appliance access level), fire-fighting lifts and “dry-risers” to pipe up water and hose-reels are required. Above 10 storeys (30.5m fire appliance access level), a wet riser, associated storage tanks and hose reels are required.

As for construction, taller buildings take longer to build because there are more floor cycles to work through, because materials must be transported higher. Blocks lower than 10 stories do not even need a tower crane. In short, shorter buildings are cheaper. But can we design them to a high density?

DEEP PLANS: MAXIMIZING SITE COVERAGE

Current high-rise typologies are narrow buildings: the slab block with a single-loading corridor can be described as a single-layer of apartments; the slab block with a double loading corridor is a double-layer arrangement; the tower block, a circular layer of apartments.

In housing, we want almost every room to have natural light and ventilation. There cannot be deep plans like that found for offices, where mechanical and electrical systems bring in artificial ventilation and lighting to the central portion of the building which are far away or cut off from the windows and the building’s edge.

The typical Malaysian apartment will have at least the living room and master bedroom having windows on the external walls of the building and less important rooms facing an air well. The depth of the unit measured from the external wall is about 8 metres. With a 2m corridor in the middle, the total width of this double-loading corridor block layout, with two layers of apartments, is not much more than 16m.

The width of the single loading corridor with only a single layer of apartments, is about half of this. The tower block, with a circular layer of apartments, can be wider; each side is typically 24m.

In contrast to these existing typologies, the Honeycomb checkerboard-plan has a depth of over 40 metres. This deep plan results in a residential floor plan that covers more of the land available on as site compared to that achieved by skinny conventional floor plans. Using the available land more efficiently allows more units to be built on every floor and so can provide higher densities without having to go taller; it should become easier to achieve high plot ratios like deep plan offices.

Figure 14Apartment Typologies and Minimum Land Required

For a comparison, we take the different floor plans, apply 60’ front setback and 25’side and rear setbacks to form the minimum site boundaries for each example. We measure the area and divide it by the number of apartment units on a typical floor to show how big an area is needed to accommodate one apartment unit. The checkerboard-plan is the most efficient as it takes up the least amount of land compared with the other examples.

Table 1 Comparison of Site Coverage: Per floor Density

	No of Units /Floor	Site Area (sf)	Site Area /Unit	Units on Floor/Acre
Woodlands Drive, Singapore	6	35,731	553.4	7.3
Single Loading Corridor
Blues Point Tower , Sydney	4	22,555	524.1	7.7
Tower Block
Membina Court, Singapore	10	50,903	473.1	8.6
Cluster Block
Binapuri Tower, Selangor	8	37,554	436.3	9.3
Double Loading Corridor
Honeycomb	10.67	43,264	376.8	10.7
Checkerboard -Plan

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